HomeMy WebLinkAboutMiddle Hoh River Resiliency Plan SEPTEMBER 2022
Photo: Raena Anderson, 10,000 Years Institute
1900 N. Northlake Way, Suite 211
Seattle, WA 98103
Natural Resources Program
Jefferson County Public Health
615 Sheridan Street
Port Townsend, WA 98368
Ph: 360.379.4498
Plan Information:
A product of Jefferson County through an agreement with Natural Systems Design, Cramer Fish Sciences and in
collaboration with Hoh Tribe Natural Resources, Trout Unlimited, 10,000 Years Institute and more than 50
resource agency representatives and valley landowners.
Authors include: Mike Ericsson, Tim Abbe, Shelby Burgess, Phil Roni, Tami Pokorny, Luke Kelly, Jill Silver, Kevin
Fetherston and Paul Pittman
Project manager: Tami Pokorny, Jefferson County Public Health
Funded by the Washington Coast Restoration and Resiliency Initiative (WCRRI)
RCO #18-2005
JCPH WQ-20-195
JCPH WQ-19-177
Special thanks to the Hoh Tribe and participants in the
Middle Hoh River Resiliency Steering and Leadership Committees.
September 2022
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TABLE OF CONTENTS
Introduction ............................................................................................................................................................... 1
Problem Statement ............................................................................................................................................ 1
Plan Assumptions and Context .......................................................................................................................... 2
Plan Goals and Objectives .................................................................................................................................. 4
Plan Overview .................................................................................................................................................... 4
Plan Steering Committee ................................................................................................................................... 4
Resiliency ........................................................................................................................................................... 4
Existing Conditions ..................................................................................................................................................... 5
Landscape Setting .............................................................................................................................................. 5
Geology & Geomorphology ............................................................................................................................... 5
Landslides ................................................................................................................................................. 7
Sediment Sources .................................................................................................................................... 9
Channel Migration Zone ........................................................................................................................ 11
Riparian and Floodplain Native Forests ........................................................................................................... 23
Methods & Study Area ........................................................................................................................... 24
Results & Discussion .............................................................................................................................. 27
Hydrology & Hydraulics ................................................................................................................................... 32
Hydrology and Boundary Conditions ..................................................................................................... 33
Mesh Development and Roughness Categories .................................................................................... 35
Modeled Infrastructure ......................................................................................................................... 35
Calibration .............................................................................................................................................. 35
Results 36
Main Stem Aquatic Habitat .............................................................................................................................. 38
Methods ................................................................................................................................................. 39
Results 43
Oxbow Canyon Reach ............................................................................................................................ 46
Willoughby Creek Reach ........................................................................................................................ 48
Morgan’s Crossing Reach ....................................................................................................................... 51
Spruce Canyon Reach ............................................................................................................................. 54
Huelsdonk-South Fork Reach ................................................................................................................. 57
Future Fish Habitat Survey Needs .......................................................................................................... 60
Anticipated Trends ................................................................................................................................. 61
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Transportation ................................................................................................................................................. 61
Trends & Anticipated Changes ................................................................................................................................. 64
Climate Change ................................................................................................................................................ 64
Sediment Sources ............................................................................................................................................ 65
Forests .............................................................................................................................................................. 66
Invasive Species Trends ................................................................................................................................... 68
Invasive Plants in the Hoh Watershed – Species, Sources, Impacts ...................................................... 72
Resiliency Corridor ........................................................................................................................................... 79
Long-Term Desired Conditions (include overarching goals and specific objectives) ....................................... 80
Intermediate-Term Desired Conditions ........................................................................................................... 81
Short-Term Desired Conditions ....................................................................................................................... 81
Local Capacity to Supply Restoration Needs............................................................................................................ 88
Introduction ..................................................................................................................................................... 88
Recent Restoration – a Snapshot of Restoration Types and Funding Over Past Five Years ............................ 90
Elements of Restoration Projects and Associated Capacity Needs ................................................................. 90
Survey Results from Restoration Practitioners ................................................................................................ 91
Inventory - Local Capacity to Supply Restoration Needs ................................................................................. 93
Things to Consider ................................................................................................................................. 93
Discussion ........................................................................................................................................................ 95
Recommendations to Increase Local Restoration Capacity ................................................................... 97
Phase II Approach .................................................................................................................................................... 98
References ............................................................................................................................................................. 100
LIST OF TABLES
Table 1. Inside the CMZ. Forest type and height class. ...................................................................................... 31
Table 2. Outside the CMZ. Forest classes and types. ......................................................................................... 32
Table 3. Estimated peak flows at each gage in the model domain.................................................................... 33
Table 4. Modeled Discharge Values at Inflow Locations ................................................................................... 34
Table 5. Calibrated Manning's n roughness values for each roughness category. ............................................ 36
Table 6. Average depth by reach for the modeled peak floods. ........................................................................ 36
Table 7. Average velocity by reach for the modeled peak floods. ..................................................................... 36
Table 8. Pool frequency standards for functioning rivers developed by NMFS (1996). .................................... 41
Table 9. Identified road segments within the Middle Hoh CMZ, Resiliency Corridor and FEMA 100-yr
floodplain.............................................................................................................................................. 62
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Table 10. The magnitude of future peak flows in the Hoh River for 2070-2099, projected as result of
the climate crisis under IPCC A1B scenario (broadly representing “business as usual” through
2050, IPCC 2000). ................................................................................................................................. 65
Table 11. Objectives and strategies necessary to achieve the resiliency goal of restoring native
vegetation............................................................................................................................................. 70
Table 12. The Invasive plant species propagation, seed number, seed viability, and allelopathy (with
sources) ................................................................................................................................................ 71
Table 13. Middle Hoh River Resiliency Plan reaches relative to ISPC reaches..................................................... 71
Table 14. The risk and hazards of invasive plant spread via streamflow, roads, equipment, hillslope
processes, and weather........................................................................................................................ 72
Table 15. The condensed acres of invasive plants inventoried and treated in 2020 within the Middle
Hoh Resiliency Plan (MHRP) reaches require surveys of 3,000 acres of forested floodplain,
channels, and river bars. ...................................................................................................................... 75
LIST OF FIGURES
Figure 1. Exposure of Pleistocene glacial outwash (gravel) and glaciolacustrine (clay) deposits near Elk
Creek on the right bank of the main stem channel at RM 19. ............................................................... 6
Figure 2. Ice River Glacier (2010) terminus with exposed pro-glacial and steep lateral moraine
sediments (left) and Blue Glacier (2009) lateral moraine and unstable hillside contributing to
rockfall on glacier (right) Courtesy of NPS. ............................................................................................ 9
Figure 3a. Photo showing relatively stable snag in river where bank erosion recruited a large tree. The
snag is deflecting flow away from the bank and helped to slow down bank erosion. Flow is
from right to left (Oct. 1, 2020, at RM 18.8). ....................................................................................... 14
Figure 3b. Photos illustrating importance of large trees in providing wood to the river that is capable of
altering channel hydraulics and slowing bank erosion (top photo of stable 9-ft diameter Sitka
Spruce with 30-ft rootwad in the Queets River, T. Abbe). Bottom photo showing high terrace
with young trees (industrial tree farm) where trees reaching the channel are quickly
transported downstream and, consequently, don’t contribute hydraulic roughness to the
channel sufficient to slow erosion (Abbe and Brooks 2011). ............................................................... 15
Figure 3c. Comparison of erosion rates in the Queets and Hoh Rivers as a function of tree size. Riparian
areas with trees greater than 21-in (0.53m) erode at less than half the rate of areas with
trees less than 21-in (Abbe et al. 2003, Abbe and Brooks 2011). ........................................................ 16
Figure 3d. Example of where recruitment of large trees to the South Fork Hoh and channel response.
Slides containing mature trees not only stopped bank erosion but also built a new floodplain
along the toe of the eroded bank. From 1990 to 2006 the river migrated 106 ft into an area
of mature timber. Once in the channel the timber halted erosion and by 2013 the active
channel had moved back to the south (Abbe et al. 2016). .................................................................. 17
Figure 3e. Example of where erosion proceeded along the South Fork Hoh due to a lack of large trees.
This site is located downstream of the previous Figure. Between 1990 and 2006 the river
migrated 153-ft (9.6-ft/yr) into a clear-cut. Bank erosion triggered a landslide that extended
550 ft into the adjacent valley margin. The landslide headscarp retreated at a rate of 24-ft/yr
from 1990 to 2013 (Abbe et al. 2016). ................................................................................................. 18
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Figure 3f. Old growth alluvial valley in Upper Hoh, about 3.6 miles upstream from ONP Hoh Visitor
Center. Flow is from right to left. Note extensive cover of old growth across valley bottom,
large number of islands and channels, and patches of old-growth within the active channel
migration zone. Small side channels extend through much of valley bottom that aren’t
visible through the forest canopy. Young deciduous forest that occupies most of the valley
bottom in areas that were logged only accounts for a relatively small portion of the valley
bottom where there was no logging. The large trees reduce the rates of channel migration
and form logjams that provide the foundations of the old-growth patches. Over millennia
the recruitment of large wood allows old-growth to colonize most of the valley bottom. ................ 19
Figure 4. Comparison of Bureau of Reclamation 2004 mapping to updated mapping conditions and
revised methodologies. Image at left is 2004 channel location mapping (colored ribbons)
and channel migration zone (black hatched zone). Image at right is updated channel
mapping with historic migration zone (red), geomorphic migration zone (dark orange),
erosion hazard area (light orange) and geotechnical setback (yellow), all included in the
updated CMZ limit (black boundary). Note that the current channel is outside of the 2004
delineated channel migration zone. ..................................................................................................... 23
Figure 5. First return 2014 LiDAR DEM of forest vegetation heights at South Fork confluence with
main stem Hoh River. Olympic National Park is clearly delineated by the much higher tree
heights. ................................................................................................................................................. 25
Figure 6. Middle Hoh River riparian forest type cover and height classes. ........................................................ 26
Figure 7. Hoh River riparian forest mosaic of cover types. October 1st, 2020, near RM 20.6 ............................ 26
Figure 8. Forest typing and channel migration zone (CMZ). ............................................................................... 27
Figure 9. Young deciduous (red alder and willow) and older mixed conifer deciduous (red alder and
Sitka spruce) forest types. October 1, 2020, near RM 20.6. Note logjam proximity to larger
conifer patch. ....................................................................................................................................... 29
Figure 10. Mature mixed (Black cottonwood, red alder, Sitka spruce) and conifer forest types (Sitka
spruce, Douglas fir). Right bank (flow from right to left), October 1, 2020, near RM 20.7. ................ 30
Figure 11. Inside CMZ. Riparian Forest Type (Ac) and Height Class (Ft/Ac). ......................................................... 31
Figure 12. Outside CMZ. Riparian Forest Type (Ac) and Height Class (Ft/Ac). ...................................................... 32
Figure 13. Locations of model inflow and outflow locations illustrated over the model domain. ....................... 34
Figure 14. Overview of the Hoh River survey area with survey reaches of interest (Piety et al. 2004) and
start and end of survey locations. ........................................................................................................ 40
Figure 15. Instantaneous flow (cfs) data at USGS Gage 12041200 – Hoh River at Highway 101 near
Forks, WA recorded and reported by USGS. Surveys were conducted between September
28th and October 1st, 2020. ................................................................................................................... 40
Figure 16. Example of jams delineated in the Morgan’s Crossing Reach (RM 21.9), shown at a 1:600
scale using aerial photography collected in March 2021 (NV5 GeoSpatial 2021). Blue
polygons depict wood in wetted channel (time of photo) and red polygons wood outside
wetted channel but within ordinary high water (bankfull) channel. Flow is from right to left. .......... 42
Figure 17. Instantaneous flow (cfs) data at USGS Gage 12041200 – Hoh River at Highway 101 near
Forks, WA recorded and reported by USGS. Aerial imagery was collected on March 20th,
2021. ..................................................................................................................................................... 43
Figure 18. Overview of the Middle Hoh River Study Area with the results from the CFS habitat surveys
conducted from September 28th to October 1st, 2020, at an average daily flow of 1,614 to
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2,652 cfs at the Highway 101 bridge (USGS Gage 12041200). For more detailed mapping see
Appendix D, Map 7. Braids and side channels were surveyed as time allowed and were not a
full census. Main stem diversion locations of un-surveyed wetted braids and side channels
were identified during surveys and general channel locations were mapped using the aerial
imagery in GIS. ...................................................................................................................................... 46
Figure 19. Overview of the Oxbow Canyon Reach with results from CFS habitat surveys from
September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200). No wetted braid or side-channel habitat was
present in this reach. The mapped photo is shown in Figure 20. ........................................................ 47
Figure 20. An example of the bedrock banks present in Oxbow Canyon (location of image shown in
Figure 19). The canyon confines the channel and prevents the formation of off-channel
habitat; therefore the reach would be primarily used as a migration corridor for salmon................. 48
Figure 21. Overview of the Willoughby Creek Reach with results from CFS habitat surveys from
September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200). Braids and side channels were surveyed as a
representative subset of the habitat available as time allowed and were not a full census.
Two side channel networks and two braided areas, shown in gray, were documented as
connected to the main channel at the time of the surveys but were not surveyed due to
time constraints. Photos are shown in Figure 22. ................................................................................ 50
Figure 22. Reach photos with locations shown in Figure 21. 1) An example of a large stretch of eroding
banks with immature industrial forest observed which demonstrates inputs of fine sediment
and clay and small wood into the river. 2) A LWJ formed pool in a side channel with
intermittent connectivity. 3) An eroding bank recruiting small Douglas firs into the channel.
4) A location of rip rap where the Upper Hoh Road runs along the right bank and constrains
the channel. The riprap provides no complexity, no cover, no hydraulic refugia and no
potential for wood recruitment. .......................................................................................................... 51
Figure 23. Overview of the Morgan’s Crossing Reach with results from CFS habitat surveys from
September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200). The Lindner side channel is the dashed line
between photo points 4 and 1. The photo was taken in the winter (leaf off) so deciduous
trees stand out as light brown areas compared to green areas of conifer forest. The current
valley bottom is dominated by small deciduous trees. Prior to logging of the valley the
number and size of large conifer patches or “islands” would have been much greater. Braids
and side channels were surveyed as a representative subset of the habitat available as time
allowed and were not a full census. One side channel complex and three braided areas,
shown in gray, were documented as connected to the main channel at the time of the
surveys but were not surveyed due to time constraints. Photos are shown in Figure 24. .................. 53
Figure 24. Reach photos with locations shown in Figure 23. 1) A long pool with ample vegetation cover
but lacking large wood jams in lower portion of Lindner Side Channel. 2) The remnants of a
landslide that has begun to be colonized by Red Alder. 3) Another landslide that appears to
be actively depositing silt and clay into the channel but is protected by a large wood jam. 4)
A log jam that runs along the bank at the Lindner Side Channel inlet along the main stem
(2020). .................................................................................................................................................. 54
Figure 25. Overview of the Spruce Canyon Reach with results from CFS habitat surveys from
September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200). Braids and side channels were surveyed as time
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allowed and were not a full census. Two side channel networks, shown in gray, were
documented as connected to the main channel at the time of the surveys but were not
surveyed due to time constraints. The mapped photo is shown in Figure 26. .................................... 56
Figure 26. Example of a pool in Spruce Canyon with remnant pilings along the left bank. The canyon
confines the channel and prevents the formation of off-channel habitat, and therefore
would primarily be used as a migration corridor for salmon. .............................................................. 57
Figure 27. Overview of the Huelsdonk-South Fork Reach with results from CFS habitat surveys from
September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200). Braids and side channels were surveyed as a
representative subset of the habitat available as time allowed and were not a full census.
Only one side channel, shown in gray, was documented as connected to the main channel at
the time of the surveys but was not surveyed due to time constraints. Photos are shown in
Figure 28. .............................................................................................................................................. 59
Figure 28. Reach photos with locations shown in Figure 27. 1) An example of a wide braided channel. 2)
A side channel with alder banks and frequent channel spanning wood. 3) A side channel that
departs from the main channel with multiple root wads and vegetated banks with slow
water refugia. 4) An example of a large log jam creating edge pool habitat in the main
channel. ................................................................................................................................................ 60
Figure 29. Scotch Broom infestation in the Morgan’s West Reach. ..................................................................... 73
Figure 30. Scotch Broom and forest type cover of the Morgan’s West Reach. ...................................................... 74
Figure 31. Summary of Scotch Broom acreage for reaches of the Middle Hoh valley. ........................................ 76
Figure 32. Summary of Reed Canary grass for reaches of the Middle Hoh Valley. ............................................... 77
Figure 33. Summary of Knotweed for reaches of the Middle Hoh Valley. ............................................................ 78
Figure 34. Summary of Herb Robert for reaches of the Middle Hoh Valley. ........................................................ 78
Figure 35. Summary of invasive plant treatment timing throughout the year. .................................................... 79
Figure 36. Illustration of portion of Upper Quinault River Valley (RM 44.3-45.8). The channel traces
show the HMZ and active channel migration zone. The area to the south shows a network of
stable side channels flowing through mature forest. Southward migration of the river has
eroded important side channel habitat crucial to salmon and the lack of big timber is
preventing the habitat from being reformed. Most recent historical channel is 2002. Since
then the river has migrated further to the south. Adapted from QIN (2006). .................................... 83
Figure 37. Conceptual geographic framework for restoring large wood cycle, floodplain forests and side
channels. The layout shows protective measures (green squares, zone 1) of property and
infrastructure within CMZ, this protection would not be needed in undeveloped areas. The
thin blue lines within zone 2-3 represent stable side channels in an area that natural would
be dominated by old-growth (see Figure 3f). The area of more active channel migration
(zone 4) the density of ELJs diminishes. Taken from QIN 2006. .......................................................... 84
Figure 38. Implementation of several phases of restoration in the Upper Quinault River. At the site the
river had moved several thousand feet to the south, ultimately destroying one home and
threatening the South Shore Road. The black symbols show constructed ELJs constructed
between 2013 and 2017. The ELJs allow water flow in-between them but discourage the
main channel from occupying the area (analogous to zone 2-3 in Figure 37). The project has
resulted in the main channel moving north while creating new side channel habitat within
the treatment area. The ELJs have also increased the number of new pools with complex
cover and created new floodplain for reforestation. ........................................................................... 85
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Figure 39. Example of large-scale restoration project to restore large wood cycle and side channel
habitat in the Cispus River (Lewis County, WA). Photos show before and after. ................................ 86
Figure 40. Same reach of the Cispus River, looking downstream on November 24, 2021, after a 100-yr
recurrence peak flow. All 24 of the ELJs are intact and undamaged. The project increased
cumulative channel length over 4-fold and increased the number of pools over 10-fold.
Photo by Eli Asher, Cowlitz Tribe.......................................................................................................... 87
Figure 41. Example of engineered logjams constructed in 2020 and 2021 in the Cispus River. The
structures were subjected to a 100-yr flood event in November 2021, only weeks after
construction. All 21 of the structures were undamaged and most collected large volumes of
wood. Flow is from right to left. Photo 11-24-21 by Eli Asher, Cowlitz Tribe. ..................................... 88
LIST OF APPENDICES
Appendix A Aquatic Habitat Field Data
Appendix B Middle Hoh River Action Plan
Appendix C 2021 List of Middle Hoh Steering Committee email list
Appendix D Map Books
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INTRODUCTION
Problem Statement
River valleys such as the Hoh are the most ecologically rich and complex areas within a watershed. River valleys
also are attractive areas for people, offering productive soils for agriculture, level ground for homes and roads
and beautiful vistas. But these attributes come with substantial risks associated with natural river processes:
flooding and erosion. Flooding, and erosion are crucial in forming and sustaining habitat. Building resiliency for
human and natural ecological communities helps to ensure they can be sustained over time, something that has
increasing urgency given the impacts of the warming climate. Resiliency for human communities is best achieved
by minimizing exposure to risks by focusing development and infrastructure in areas outside flood and erosion
hazard areas. This basic strategy is consistent with providing ecologic communities with the space they need
within the productive habitat within those hazard areas. Where defensive measures to protect infrastructure
and development are unavoidable, they should be done to create and sustain the natural habitat of the river.
Ecological resiliency also requires restoring natural conditions impacted by historic development such as the
conditions associated old-growth valley forest that once occupied much of the Middle Hoh River valley. The
intent of a resiliency plan is to provide a description of the Middle Hoh and its watershed, layout
recommendations for improving resiliency for the river’s ecosystem and human communities and provide a
structure for future communications and decision making. The plan is a living document that is intended to be
updated as needed. In the process of developing this initial edition the project has outreach and engaged a
leadership group that have greatly improved communications and transparency in river management.
There are no formal programs for comprehensive management of river valleys. Management typically reflects
the diversity of landownership and infrastructure found in a valley; thus, actions of different entities can
frequently conflict with one another. The lack of communication between responsible entities can lead to
unintended impacts to ecosystems and human communities. The Middle Hoh Resiliency Plan is intended to
establish a unifying structure to better manage this very important river. In developing the initial edition of the
resiliency plan Jefferson County reached out to a broad community of people with ties to the Middle Hoh valley,
forming the Middle Hoh Steering Committee which has been engaged throughout the process. Regular meetings
of the Steering Committee have improved communications regarding resource management and infrastructure
with the Hoh Valley. The committee includes representatives from the Hoh Tribe, Jefferson County, Washington
State Departments of Natural Resources (WDNR) and Fish & Wildlife (WDFW), The Nature Conservancy (TNC),
Trout Unlimited (TU), the 10,000 Years Institute (10K), the Coast Salmon Partnership, the Wild Salmon Center,
local businesses, river guides, private landowners and federal agencies.
The Hoh Tribe, Chalá·at: People of the Hoh River, lived sustainably within the watershed for millennia, long
before Europeans first came to the Olympic Peninsula. On July 1, 1855 the Hoh Tribe and the United States
signed the Quinault Treaty, guaranteeing the Tribe’s Rights to the natural resources of their usual and
accustomed lands. Hoh Tribal members continue to depend economically, culturally, and spiritually upon natural
resources. The first European settlers, John and Cornelius Huelsdonk, came to the Hoh valley in 1892. The Hoh
River watershed supports a diverse ecosystem that ranges from alpine glaciers to temperate rainforests and is
home to all five species of Pacific salmon (Chinook, Coho, Sockeye, Chum, Pink) along with Steelhead, Bull Trout
and Cutthroat Trout. The native peoples’ deep respect for the river and its natural rhythm of flooding and
shifting channel banks was key to sustaining a balanced human and wildlife ecosystem. Over the last century,
the watershed has undergone changes at a scale not seen since the last glaciation nor witnessed by its original
inhabitants, including local and regional flow and temperature changes occurring due to a warming climate,
accelerated retreat of major glaciers altering sediment and flow regimes, and extensive road building and
deforestation beginning in the late 1800’s. Human changes in the basin include the loss of primary and
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secondary floodplain forest, including most of the largest trees, road building and repairs, installation of long
rock revetments and the establishment and spread of numerous invasive plant species. These actions and
activities have altered the natural processes that create and sustain aquatic and riparian habitat, contributing to
plunging salmon populations. In particular the clearing and high-grading of large trees from the riparian corridor
and channel banks removed that key structural element responsible for maintaining and sustaining the rich
habitat diversity of the Hoh. With the large trees gone the main stem channel is now free to migrate across the
valley bottom unimpeded, frequently recycling floodplains and making it impossible for a mature riparian
corridor to re-establish for generations, if ever. The accelerated bank erosion rates have also led to property
loss, elevated flood and erosion risk and costly, repetitive road repairs and associated invasive plant
introductions.
The primary public access in the watershed is the Upper Hoh Road, located parallel to and north of the river.
Washouts threaten access for local residents as well as for visitors to Olympic National Park (ONP); thus, directly
impacting the economy of this important local and scenic valley as well as the broader region. Road repairs are
expensive and directly destroy salmon habitat; channel margins are some of the most important zones for
juvenile and adult salmon where they expect to find a submerged forest to hide within and feed on a complex
food web. The chronic threat of erosion puts the valley’s homes, roads and other human improvements at risk -
and will become more severe in the coming decades. The realization that the river community is not currently as
resilient as it can be prompted Jefferson County to develop a resiliency plan for the Middle Hoh River, extending
from the ONP boundary to Oxbow Canyon (Appendix D, Map 1). This plan will better identify flood and erosion
risks to residents, infrastructure and habitat and detail appropriate and necessary measures that can be taken to
reduce these risks, while allowing the Hoh River and its floodplain space to support healthy, self-sustaining
salmon and wildlife populations. A multi-disciplinary team of locals, scientists, conservation groups, county
officials and tribal representatives have developed this plan working together with the Hoh Tribe, greater
community, state and federal agencies and the recreational fishing community. The Plan’s goal is to bring
forward a collective voice for the river and floodplain with the aim to develop, prioritize and implement actions
that are mutually beneficial to the community and wildlife. This Resiliency Plan will also open additional
opportunities for funding as well as reduce regulatory costs and timelines that have impacted past and current
projects.
The Plan establishes an initial template that is intended to be periodically appended as new information is made
available. This first edition utilized the best available science at the time and solicited the input of numerous
individuals with intimate knowledge of the Hoh River. The Plan and the leadership team will hopefully be
sustained permanently, like commitments to maintain infrastructure. Most importantly the Plan is intended to
bring the community and numerous entities responsible for managing resources in the Middle Hoh River valley
together under one tent.
Plan Assumptions and Context
This Plan assumes the following:
The Middle Hoh Resiliency Plan is “living” document intended to enhance management of the Middle
Hoh River valley to the benefit of people and natural resources.
People, governments, non-governmental organizations (NGOs) who live, and work in the Middle Hoh
River valley will continue to contribute their time to help ensure a healthy future for the river and its fish
and wildlife. To this end, the Middle Hoh Steering Committee will continue to meet, and the Resiliency
Plan will be updated and revised to best manage the river
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Infrastructure improvements and repairs by Jefferson County, Olympic National Park and the Federal
Highway Administration will be communicated to the Middle Hoh Steering Committee during initial
planning through implementation and be consistent with the Resiliency Plan.
Analyses performed as part of this plan development relied significantly on data five or more years old,
such as the 2013/2014 LiDAR topography used for hydraulic modeling and forest characterization,
Implementation of the accompanying Action Plan will advance the goals of the Resiliency Plan. Each
action will only proceed with support of the Hoh Tribe, local residents, the salmon restoration
community and governmental agencies.
Tributaries and fish passage remain important to the successful recovery of salmon stocks in the Hoh
River and should be included and considered for measures to improve habitat conditions, in tandem
with efforts in this document focused on the main stem channel and floodplains,
Restoration actions used successfully in similar rivers can be successfully implemented in the Middle
Hoh River,
Sitka spruce and other native conifers will maintain their rate of growth on the floodplain,
Control of invasive species in the valley will be continued to ensure the regrowth and resiliency of
mature forested floodplains,
Climate change projects are taken from the Intergovernmental Panel on Climate Change (IPCC)
Assessment Report (www.ipcc.ch). Regional climate will change over time largely consistent with
University of Washington Climate Impact Group (https://cig.uw.edu) projections,
Rules and regulations governing timber harvest remain in place,
Wildfires will continue to be rare and generally under 1,000-acres (ac),
This planning process began in earnest in early 2020 through monthly in-person meetings which, as a result of
the COVID-19 pandemic, were held online beginning in March of that year and continuing through 2021.
The Resiliency Plan established a structure that has brought together the people who live, work and manage
resources within the river valley and provide the following:
1. an understanding of the processes and conditions that define the river’s ecology and impact the human
community,
2. a source of information and experts (e.g., natural resources, hazards, regulations, infrastructure),
3. a network for communication regarding management actions,
4. a safe structure for debate that is respectful of different perspectives and encourages transparency in
decision-making that impacts natural resources and people,
5. works to develop a shared vision for one of the most unique and intact large river ecosystems in the
contiguous United States,
6. provides guidance for protecting and restoring critical salmon habitat as well as supporting the
prosperity of the local communities. This plan provides an update to previous work (Piety er al 2004) on
the changes to the geomorphology and hydraulics of this large river and possible human responses,
based on the experience of the authors across multiple Washington river systems, including the Hoh
River, over decades.
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Plan Goals and Objectives
The primary goal of this plan is to produce a collective voice for the river and floodplain based on a shared
scientific foundation. Its objectives are to develop, prioritize and implement prioritized actions that are mutually
beneficial to the community and wildlife as articulated in Appendix B- Middle Hoh River Action Plan. The Action
Plan sets out a detailed strategy for improving community and ecosystem resiliency in the Middle Hoh River
over the next 80+ years (yrs). Due to the size and characteristics of the river itself, the scale and intensity of
human alteration, as well as the need to act quickly to restore salmon habitat and adapt to climate change
impacts, the plans necessarily describe an assertive path to restoration. It has been collaboratively developed
with the local community, property owners and agencies responsible for land management and infrastructure.
Plan Overview
This plan is separated into six broad topics covering existing conditions in the project reach, trends and
anticipated responses, desired conditions, resiliency opportunities, local capacity to perform work, and the
Action Plan. Each topic is presented as follows: Current Conditions; Anticipated Changes; Desired Conditions;
Next Steps to Achieve Desired Conditions; Capacity to Hire Locally; and Develop Overarching Strategies.
Descriptions of existing conditions are provided to establish new “baseline” conditions in the project reach in
order to identify opportunities to improve resiliency. System trends describe how conditions have evolved in
more recent history and anticipates future system responses over 80-yrs and accounting for climate change
(IPCC 2021) under a no-action scenario (i.e., no proactive measures to improve system resiliency).
Plan Steering Committee
A project steering committee was convened monthly during the development of this plan to provide a forum for
collaboration with the Hoh Tribe, various government agencies, non-government organizations, local
landowners and non-local river users. This diverse group provided information and data resources, coordinated
outreach to the community and contributed meaningful and critical feedback on assessments completed,
proposed actions, and interim drafts of this plan. Governments, agencies and organizations represented in the
steering committee included:
Hoh Tribe
Jefferson County
10,000 Years Institute
Coast Salmon Partnership
Hoh River Trust
Olympic National Park
Olympic Natural Resources
Center
North Pacific Salmon Lead
Entity
Pacific Coast Salmon
Coalition
The Nature Conservancy
Trout Unlimited
Olympic National Forest
Washington Department
of Fish and Wildlife
(WDFW)
Washington Department
of Natural Resources (DNR)
Wild Salmon Center
Resiliency
In the context of out watersheds, resiliency can be defined as the capacity of an ecosystem or community to
accommodate and recover from disturbance and environmental change without loss of overall function. A flood
resilient community is one that can recover from major floods quickly with little damage or harm to the
community; achievable by focusing on providing adequate space for natural flooding processes to occur by
limiting exposure of vulnerable assets (homes, roads, utilities, out-buildings, etc.). Likewise, a resilient
ecosystem is able to maintain diverse and productive wildlife habitat despite being subjected to disturbances
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such as fire, landslides and climate induced increases in air, stream and soil temperature, and the frequency,
duration and magnitude of peak flows, and lower summertime flows.
This Resiliency Plan is intended to provide a scientific foundation and a blueprint for necessary measures and
actions that can be made to maximize the resiliency of the community and ecosystem of the Middle Hoh River
valley. When resiliency is lacking, the environment and community suffer significant damage and recover slowly
from change, whether coming quickly like a flood or more gradually like extended drought, invasive species
spread and river aggradation. Greater damage requires more money to fix, oftentimes repeatedly, and can
impact vital services. In an era where we are looking ahead to projected increases in the frequency of
disturbances (floods, landslides, etc.) as a result of the current climate crisis, future generations of citizens and
wildlife of the Middle Hoh valley will benefit from a science-based plan for resiliency.
EXISTING CONDITIONS
Landscape Setting
The Hoh River is located on the West Coast of Washington State, originates from glaciers high on Mount
Olympus and descends 7,980-feet (ft) over 57-miles (mi) before entering the Pacific Ocean. The watershed
encompasses 298 mi2, the upper 57% of the basin lies within Olympic National Park (ONP) and is considered to
be pristine temperate rainforest, home to some of the largest trees in the United States (McMillan and Starr
2008; NPCLE 2020). Downstream of ONP the Hoh basin is primarily a mix of public open space, state and private
forestland, private residences and local businesses, with forestlands the dominant land cover type (93%) on the
valley bottom outside of the active channel. The full-time population is around 20 residents, with approximately
80,000 vehicles entering ONP via the Upper Hoh Road (FHWA 2021). The watershed receives an average annual
precipitation of 155-inches (in) falling as rain and snow depending on time of year and elevation, with a large
precipitation gradient from 240-in above the glaciers near the summit of Mt. Olympus at 7,980-ft, to 93-in at the
coast (Lieb and Perry 2005). The cobble-gravel bed river flows generally east to west gaining flow from several
major non-glacial tributaries draining primarily industrial timber lands. River flows fluctuate throughout the year
with the highest monthly averages occurring in November and minimum averages in September, with a
sustained freshet typically extending into June (Lieb and Perry 2005).
The Middle Hoh project reach extends from the ONP boundary to Highway 101, covering 15-river miles (RM)
with an average slope of 0.3% (Appendix D, Map 1). The upstream end of the reach begins as the river
transitions from the confined steep upper watershed draining ONP to a broad valley with wide floodplains and
lower slope. The valley is approximately 1800-ft wide on average, with Pleistocene glacial terraces along the
margins composed of outwash, drift and glaciolacustrine deposits. The 15-mi project reach is divided into five
contiguous distinct geomorphic reaches, adopted from previous work completed by the Bureau of Reclamation
(Piety et. al. 2004).
Geology & Geomorphology
The geologic and glacial history of the Olympic Mountains are primary drivers influencing conditions in the Hoh
River basin. The Olympic Mountain Range was and continues to be uplifted resulting from the Juan de Fuca plate
subducting under the North American plate, creating a mélange of oceanic sedimentary rocks accreted onto the
North American plate at the convergent boundary (Pazzaglia et al 2003). These rocks are uplifted, folded,
fractured and experience low-grade metamorphism, weakening the rocks and making them highly erodible.
These rocks underlie the watershed, and are exposed primarily at the eastern, highest portion of the watershed
in steep mountainous terrain (Appendix D, Map 2). This bedrock is exposed in a few locations within the study
reach on the valley floor, but the predominant geologic units are unconsolidated/poorly-consolidated glacial
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deposits and post-glacial alluvium/colluvium. Where bedrock is present, it has significant influence on both
lateral channel migration and vertical gradient control. Bedrock controls are present in two locations within the
study reach: Spruce Canyon (RM 26) and Oxbow Canyon (RM 17).
During the Pleistocene from 54,000 – 18,000-yr B.P. alpine glaciers advanced and retreated up and down the
Hoh valley at least four times (Thackray 2001). Glacial processes both widened the valley, scoured the valley,
and then deposited a complex set of overlapping glacial sediments within the valley as the glaciers receded.
Glacial deposits in the valley include moraines, tills, alluvial outwash, lacustrine, sub-glacial, ice-marginal, and
ablation drifts. Deposits are present as low to moderately high banks along the margins of the active
geomorphic migration zone. Of note is the presence of thick clay deposits in the channel banks and valley
margins in the vicinity of Elk Creek near RM 19 and Owl Creek near RM 27, just upstream of Oxbow and Spruce
Canyons, respectively (Figure 1). Oxbow Canyon formed as the Hoh cut through a mapped terminal moraine,
formed at the end of an advancing alpine glacier. Once the glacier retreated a pro-glacial lake formed behind the
moraine as meltwater accumulated, depositing the clay layers observed in the channel banks today. Once the
river breached the moraine it carved Oxbow Canyon and drained the lake and were subsequently buried/filled
with coarse outwash deposits. While not formally mapped, we interpret a similar course of events transpired to
form Spruce Canyon, leaving behind the abundant and thick clay deposits found upstream to Canyon Creek.
Figure 1. Exposure of Pleistocene glacial outwash (gravel) and glaciolacustrine (clay) deposits near Elk Creek
on the right bank of the main stem channel at RM 19.
Unconsolidated alluvial sediments that range from sand and gravels to floodplain silts comprise more recent
Holocene post-glacial deposits. Also included in this geologic group are alluvial fan deposits, colluvium, and
recent mass-wasting deposits. The active geomorphic migration zone is comprised primarily of post-glacial
fluvial deposits forming readily erodible low banks, and is the predominant channel bank material within the
study reach.
The Middle Hoh River has a variety of channel morphologies ranging from confined (no floodplain) single thread
boulder-bedrock channels (Oxbow and Spruce Canyons) to different unconfined (floodplain) alluvial channels
that include meandering channel reaches, wide braiding (large gravel bars) channel reaches, and multi-channel
island dominated reaches. Prior to 1900, geomorphic processes in the Middle Hoh were closely linked to the
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extensive floodplain and slope-side forests of mature conifers as they interacted with flow. Natural recruitment
into the channel from bank erosion, windthrow or other means forces the river to move or flow around the tree.
If of sufficient size and aided with rootwad and branches, the tree remains stable in the channel and will alter
flow characteristics that initiate geomorphic processes. Flow can be deflected into an adjacent bank initiating
erosion, flow can be split forming an island between channel threads with the tree at the upstream end, flow
can be forced downward as the channel impinges on the tree forcing a scour pool to form in the channel bed.
The presence of these trees, particularly those capable of remaining embedded in the channel, were the literal
backbone of the system providing the long-term stability that fostered the development of critical salmon
habitat. While the geographic setting differs from the Middle Hoh, the Upper Hoh within ONP provides an
excellent example of the importance of large trees in driving the geomorphic processes, leading to a more stable
and resilient system.
Early homesteaders began arriving in the late 1890’s began clearing land for fields and wood for homes and
barns. Commercial timber operators began harvesting more large trees from the riparian forest, and over time
high-grading and more clearing continued. The loss of the large trees and widespread clearing ultimately led to a
riparian forest largely devoid of the large trees capable of remaining stable in the channel and responsible for
driving the geomorphic processes that maintained the stable channel and supported healthy salmon runs. Once
the channel began to erode channel banks lacking large trees, there was nothing to impede further erosion of
the floodplain and the active channel began to widen and freely migrate across the valley bottom. This resultant
highly dynamic system limits the ability for the floodplain forests to recover from erosion, before the channel is
back to reclaim the land and small trees beginning to take hold. The historic air photo record portrays a system
gradually unraveling throughout the 20th and now 21st century. The channel through alluvial reaches of the river
has progressively become simplified from an anabranch planform with, multiple channel threads, to an irregular
wandering channel type that is less predictable over time than other forms because of characteristic higher
erosion rates and a relatively high potential for avulsions (new channel courses that take completely new path
through the floodplain). The high natural sediment supply to the Middle Hoh further exacerbates channel
migration and is expected to increase as the source glaciers recede due to the climate crisis.
Landslides
Landslides are common in the Hoh River watershed. The stability of slopes is controlled by the underlying
geology, topography, vegetation, rainfall duration/intensity and natural and human disturbances. Natural
disturbances that alter forest cover can initiate landslides and include fire (historically rare in the Middle Hoh),
frequent windstorms that alter forest cover, and channel migration. Human disturbances such as road, drainage
and forest clearing can destabilized slopes. Natural variability across the watershed creates the potential for
three types of mass wasting: rapid shallow landslides, deep-seated rotational landslides and debris flows. Rapid
shallow landslides are translational (parallel) slope failures occurring on a relatively planar surface, typically
associated with a zone of weakness in the soil (e.g., limit of root depth) or soil contact with bedrock, and are the
most common mass wasting process in the watershed. These slides are common along ridgelines bordering the
Middle Hoh and frequently transform into debris flows once the failed material reaches creek channels,
sometimes continuing for a considerable distance downstream.
Deep seated rotational landslides occur on a curved failure plane within the slope, with the displaced material
rotating during failure, leaving a head-scarp at the up-gradient end and rotated material at the toe. Deep seated
slides are typically associated with a deep impermeable layer such as the glacial lacustrine clay deposits
common in the Hoh Valley and can occur slowly or rapidly. Surface exposures of these deep clay layers are
commonly visible at the toe of hillslopes along the river such as at RM 26.8 on the left bank, and in many
tributaries to the Hoh. Fine sediment inputs to the Middle Hoh from these exposed clay layers appears limited,
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however, significant failure could result in catastrophic damage and deliver large quantities of fine sediment to
the river.
The third type are debris flows resembling wet concrete in consistency and can be very damaging where they
build up mass and momentum. Debris flows happen when water pore pressure exceeds the soil strength and
gravitational forces trigger a landslide that develops into a debris flow, usually in steep headwater channels or
hillslopes. If there is sufficient large wood in the path of the debris flow, it can slow or halt the flow by limiting
the flow from increasing in mass and momentum. Where flows encounter little resistance, they quickly gain
mass and momentum, and scour out channels all the way down to the Hoh valley where they deposit the load of
mobilized sediment and wood. Numerous debris flows have occurred in the many tributaries of the Middle Hoh,
commonly resulting in channels scoured of large wood and sediment, including spawning gravels (McMillan and
Starr 2008). Runout from debris flows can travel to the confluence with the main stem channel or floodplain,
typically stopping shortly after reaching the valley floor where the gradient diminishes rapidly.
The resiliency plan includes an inventory of landslides that incorporates previous work (Parks 1999, McHenry
2001), as well as identification and inclusion of new landslides using more recent data. The primary source of
previously identified landslides was from Parks (1999), and a hill shade generated from the 2013 LiDAR was the
primary data used to identify new, previously unidentified landslides. Three NSD geologists licensed in the state
of Washington reviewed the LiDAR hill shade for surface forms indicating mass wasting had occurred,
delineating the initiation point and runout to the failed material. A total of 202 landslides encompassing 730-ac
were delineated by Parks (1999), with an additional 19 landslides mapped by NSD covering 123-ac (Appendix D,
Map 3). Most of the rotational and translational failures occur along the contact between Quaternary alluvial
deposits and unconsolidated Pleistocene glacial deposits at the valley margins. NSD mapped several landslides in
the vicinity of Spruce Canyon and upstream to the confluence with the South Fork Hoh River that initiated in fine
grained glaciolacustrine deposits not mapped previously (Appendix D, Map 2). These deposits are prone to
deep-seated slope failure (McHenry 2001) and are understood to have been deposited in a proglacial lake
impounded by a terminal moraine that crossed the valley near Spruce Canyon. Meltwater from the receding
glaciers would have backed up behind the moraine, depositing the thinly bedded clays and silts.
In addition to mapping landslides that have occurred over time in the Hoh valley, the results of a predictive
model of shallow rapid slope stability are included on the landslide inventory maps (Appendix D, Map 3) (Shaw
and Johnson 1995). The model does not predict the potential for deep-seated landslides or debris flows. The
model results from DNR show classified slope stability based on slope gradient and curvature, landslide
inventories, geology, precipitation, etc. into zones of high, medium and low probability for failure. The models
used were SMORPH (Shaw and Johnson 1995) and SHALSTAB (Montgomery and Dietrich 1994, the terrain
surface used for the analysis was a 10-meter DEM with an accuracy of +/- 35-ft. The results show almost all the
steep high terrain forming the valley margins are in the medium to high probability zones, as well as the same
boundary between Quaternary alluvial deposits and Pleistocene glacial deposits where NSD mapped several
landslides (Appendix D, Map 3).
These results highlight the inherent instability of the watershed, high potential for mass wasting primarily due to
geologic and hydrologic forces greatly exacerbated by forest clearing and road construction. Direct delivery of
failed slope sediments to the channel can result in large sediment pulses propagating downstream, or remain
chronic high-sediment load contributors to the channel. Larger failures that could dramatically alter the course
of the Hoh are possible, potentially resulting in miles of flooding and erosion up and downstream. Locations that
are known to be susceptible to failure, exhibit indications of impeding failure and/or are located above sensitive
areas and populations, should be monitored and appropriate mitigating measures taken.
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Sediment Sources
The sediment supply in the upper watershed of the Hoh River is virtually limitless given the high relief, weak rock
and abundant unconsolidated glacial deposits. This sediment is generated from glacial processes, rainfall, slope
failures, road disturbance and hillslope surface erosion. The glaciers descending Mount Olympus are the
predominant source of sediment to the Hoh River as they grind away at the valley floor and margins. As these
glaciers recede over the next century, sediment once buttressed by ice against the valley walls will become
exposed on steep unvegetated slopes. These deposits, prone to shallow rapid failure, have the potential to
deliver copious amounts of additional sediment to the already sediment-laden pro-glacial Hoh River.
Additionally, rockfall and rockslides deliver sediment to the river and have been increasing in frequency as the
ice buttressing the over-steepened valley walls retreats (Lyons, E. 2003) (Figure 2). All these glacier-derived
sediments can be delivered to the river gradually over time or as a sediment pulse or wedge that will propagate
downstream, varying sediment delivery downstream over time. Recent studies have concluded that these
processes are occurring at an accelerated rate due to the changing climate (Riedel et. al. 2015 and East et. al.
2016), increasing the sediment supply downstream, and initiating channel widening and taking on a more
braided form (East et. al/ 2016). Where present, the native forests have played a significant role in limiting wide
scale erosion, providing resiliency as sediment flux varies over time. Where absent, resulting young forests
provide little resistance to channel migration as the channel expands to accommodate sediment pulses.
Figure 2. Ice River Glacier (2010) terminus with exposed pro-glacial and steep lateral moraine sediments
(left) and Blue Glacier (2009) lateral moraine and unstable hillside contributing to rockfall on glacier (right)
Courtesy of NPS.
Landslide susceptibility mapping by the DNR of the contributing basin shows that mass wasting potential in the
watershed is high (Appendix D, Map 3). While upper watershed tributaries continuously transport sediment to
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the river system, significant volumes of sediment delivered to the channel from mass wasting processes tend to
occur episodically and are typically associated with high intensity precipitation events.
Sediment Budget
Estimates of sediment production and transport were taken from published studies where available for each of
the primary sources identified. Nelson (1986) estimated that 630,000 tons of suspended sediment is transported
by the Hoh River (measured at the mouth) annually, and that 60% of that load is from the portion of the
watershed draining ONP. Because the Middle Hoh reach begins at this same location, we have used 60% of the
suspended sediment load reported by Nelson (1986) at the mouth, or 378,000-tons/yr, as an appropriate
average annual suspended sediment load entering the project reach. This value, or 810-tons/yr/km2 when scaled
to the drainage area, is in-line with other findings that coastal Pacific Northwest rivers have sediment loads
between 100 – 500-tons/yr/km2 and rivers draining the glaciated Mt. Rainier are on the order of 1,000-
tons/yr/km2 (Czuba et. al. 2012). Scaling the suspended sediment load to the downstream end of the project
reach at Highway 101 yields a load of 815-tons/yr/km2, greater than the load per unit area within ONP. The
difference in sediment load per unit area is due to a combination of human disturbances over time within the
Middle Hoh reach.
Because only the suspended sediment load was measured (Nelson 1986), estimates for bedload are needed to
determine a total sediment load (dissolved loads are not accounted for in this assessment). The fraction of the
total sediment load constituting bedload varies as a function of eroding surface characteristics, slope steepness,
discharge magnitude and underlying geology and typically fall within the range of 1 – 15% of the total load, but
can be as high as 87% or greater (Babinski 2005). Overall, the percentage of the total load as bedload increases
away from the equator and for terrains sculpted by previous glaciations (Babinski 2005). Due to this uncertainty,
estimates of bedload were calculated as a percentage of the total load between 1 – 30%, or between 381,780 –
491,400-tons/yr at the ONP boundary.
Parks (1999) found that sediment loading within the Middle Hoh from hillslope fine sediment production to be
1,739-tons/yr and 2,147-tons/yr contributing from roads, Logan et. al. (1991) estimated 94,350-tons/yr of coarse
sediment loading from mass wasting and 16,405 tons/yr contributing from tributaries (Czuba et. al. 2012) within
the Middle Hoh. To estimate sediment production within ONP from these same sources we determined the
tons/yr/mi2 of sediment produced in the Middle Hoh and scaled to an appropriate value for within ONP due to
the difference in land cover and use. We estimated hillslope fine sediment production within ONP would be 50%
that outside of ONP, sediment contribution from roads to be 1% relative to outside ONP, coarse sediment
loading from mass wasting to be 90% and from tributaries to be 75% of that outside ONP per unit area. The
resultant estimated sediment production within ONP from hillslope fine sediment is 1,840-tons/yr, from roads is
45-tons/yr, 179,820-tons/yr from mass wasting and 26,055-tons/yr from tributary inputs.
Summing these sources yields 207,762-tons/yr of sediment production within ONP, however this does not
account for the contribution of sediment generated from the many glaciers feeding the Hoh River. Simply
subtracting the total sediment production estimated within ONP (207,762-tons/yr) from the total sediment load
exiting ONP (381,780 – 491,400-tons/yr depending on 1 - 3% bedload) yields an estimated sediment production
between 174,018 – 283,638-tons/yr from glaciers, accounting for 46 – 58% of the total sediment load entering
the reach. At the downstream end of the project reach the relative contribution of sediment from glaciers
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diminishes to between 40 – 54%. This approach, equating the sediment load transported by the Hoh River to a
sediment production rate, neglects any change in sediment storage within the project reach (i.e. bank erosion
reducing sediment storage, aggradation increasing storage). Based on these findings glacial processes are the
dominant sediment producer within ONP. As the climate warms and the glaciers recede, sediment production
should be expected to increase in the near-term (decades) as sediments previously shielded and buttressed by
ice are now exposed to erosive forces. As the glaciers recede and sediment production increases the average
total sediment load will increase in-kind, likely with a larger proportion of the total load as bedload. Once the
available sediment has been mobilized and the glacier is reduced to the extent that it is no longer producing new
sediment due to lack the mass, sediment stored in the system will begin to evacuate, and will continue to do so
ultimately leading to widespread incision as the system adjusts. Further study into the timing of transitions from
excess available sediment to lack thereof would further assist planning efforts.
Channel Migration Zone
This chapter summarizes the methods and analyses utilized to develop a Channel Migration Zone (CMZ)
(Appendix D, Map 4) map for the Middle Hoh River. Over the last century the watershed and river valley have
been extensively manipulated to meet human needs and expectations of the population, war time needs (large
spruce) and commercial industry. Local, and more expansive changes have affected flow, channel banks,
floodplains, vegetation, sediment, air and soil temperatures, precipitation patterns and land use. New landscape
conditions, in turn, affect the physical processes that create and sustain aquatic and riparian habitat essential for
healthy salmon populations. New conditions also place human communities at risk with regards to flooding,
channel incision and bank erosion. This assessment is intended to provide the best available science to better
define fluvial-related risks and opportunities to residents, infrastructure and habitat.
Methods
The Washington State Department of Ecology Publication (#03-06-027) “A Framework for Delineating Channel
Migration Zones” was the general guidance used to develop a new CMZ. The erosion and avulsion hazards
analysis “takes into account trends in channel movement, context of disturbance history and changes in
boundary conditions, as well as topography, bank erodibility, hydrology, sediment supply and woody debris
loading” (Rapp et al, 2003).
The purpose of mapping the CMZ for the Middle Hoh was necessitated by both riverine hazard planning and
ecosystem recovery planning. The intent of this study is to provide a technical background document and set of
maps to help guide decision makers in adopting a CMZ and developing comprehensive flood hazard and
ecological planning. To the extent possible, CMZ mapping for this analysis builds upon existing knowledge and
information. This included previous mapping efforts and studies. In particular, the Geomorphic Assessment of
Hoh River in Washington State ((Piety et al 2004), LiDAR topography, geologic mapping, other geomorphic
studies, air photo analysis, interviews, anecdotal accounts, and reconnaissance-level field investigation provided
the foundation of information for this analysis.
Definitions
The definitions used in this analysis build on the definitions in regulatory and guidance documents but have
been modified to fit the conditions and processes specific to the Middle Hoh River. The definitions used are:
Historic Migration Zone (HMZ): The HMZ is a composite of the historic locations of the river as determined
from historic information and interpretation, over some length of historic record.
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Active Geomorphic Migration Zone (GMZ): The GMZ is “the geographic area where a stream or river has
been and will be susceptible to channel erosion and/or channel occupation” (Rapp et al, 2003); the GMZ
considers a time period greater than the historic photo record.
Erosion Hazard Area (EHA): The EHA in this analysis refers to the hazards resulting from lateral migration
of a channel through bank erosion that occurs from channel expansion, channel meandering, channel
course changes, or channel bank and fluvially related slope failures. The EHA is a predicted horizontal
channel migration potential area. Lateral erosion is not necessarily limited to the floodplain or areas
inundated during the 100-yr flood event.
Avulsion Hazard Area (AHZ): The AHZ describes an area susceptible to multiple alluvial hazards associated
with rapid channel course changes or temporary channelization of flow that in addition to having flooding
hazards, instantaneously becomes an erosion hazard.
Geotechnical Hazard Area (GHA): The GHA describes an area of potential slope instability driven by
channel migration processes. For this study the fluvial-related geotechnical hazards are shown as an
overlay on the maps.
Alluvial Fan Hazard Area (AFH): The AFH describes an area where alluvial fan processes have occurred
based on landform interpretation. Alluvial fan hazards include flooding, scour, erosion, avulsion,
deposition, and debris impacts. For this study, AFHs are shown as an overlay on the maps.
Channel Migration Zone (CMZ): The cumulative area of the HMZ, GMZ, EHA, AHA, and GHA is the CMZ.
The State of Washington, in [WAC 173-26-221(2)(c)(iv)(3)(b)] describes this concept further as: “The
dynamic physical processes of rivers, including the movement of water, sediment and wood, cause the
river channel in some areas to move laterally, or "migrate," over time. This is a natural process in response
to gravity and topography and allows the river to release energy and distribute its sediment load.”
A thorough review of previous data and literature was conducted as part of the development of this plan. The
intent was to build extensively from the existing information. The Geomorphic Assessment of Hoh River in
Washington State (Piety et al 2004) was identified as a key document. From this review, data gaps and updates
were identified, and additional analyses were conducted to supplement and update the existing information. A
synthesis of the key findings from this study is provided below.
The Bureau of Reclamation study was a detailed geomorphic analysis of the Middle Hoh River between Oxbow
Canyon (RM 17) to Mount Tom Creek (RM 40). The purpose of the analysis was to improve the understanding of
channel processes and human impacts on the channel conditions. The analysis included channel migration
mapping, hydrologic analysis, woody debris conditions, sediment estimates, and management considerations.
Key findings were:
The frequency and magnitude of floods has been increasing over the past 50-yrs
Channel migration and erosion rates increased with increased flood magnitude
Channel planform changes, particularly from avulsion, caused the highest localized erosion rates in the
photo record (1939 – 2002)
Human impacts, particularly from loss of mature riparian woody vegetation and stable instream logjams,
increased erosion rates in the study area
Sediment supply and transport appeared balanced based on geomorphic indicators.
Field and Desktop Observations
Channel migration is lateral movement of the channel and was observed to occur in two primary ways on the
Middle Hoh River: 1) progressive lateral erosion of channel banks and valley margins, and 2) relict channel or
topographic capture and channel realignment (avulsions). Dynamic rates of channel migration from lateral
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erosion were observed in field and desktop analysis. Evidence of regular avulsions, or rapid changes in channel
location typically to a shorter flow path, was also apparent in both desktop and field observations. Mapping and
interpreting lateral erosion and avulsion potential included analysis of different physical conditions that tend to
drive these processes. Primary drivers and conditions observed influencing channel migration evaluated were:
valley geologic composition
valley vegetation
sediment deposition trends
channel forms.
Observed Valley Geologic Composition
Field observations of geologic composition revealed that post-glacial alluvial and glacial geology (low- moderate
bank) groups are the predominant bank composition within the geomorphic migration zone. A recent maximum
annual lateral erosion rate of 75-ft/yr was measured in post-glacial alluvial group sediments (low bank, pasture)
at one location in the reach. Anecdotally, maximum annual erosion rates are reported to be double or triple that
rate. The glacial group sediments were observed to have more variable erosion rates depending upon the
geologic composition which ranged from lacustrine silts/clays to coarse outwash. The lacustrine silts appear to
have lower erosion rates than the outwash but had higher potential for slope instability than the outwash
deposits. The outwash deposits likely have erosion rates similar to the erosion rates of the post-glacial alluvial
group deposits. The bedrock was metamorphosed marine silt/sandstone and was relatively erosion resistant
over the planning-horizon of this study. For the mapping analysis, we considered three geologic groups for
erosion potential mapping:
Post-glacial (Holocene) Alluvial Group and Glacial) Group (Low-Moderate Bank Height)
Glacial Group (High Bank)
Bedrock Group
While short term (< 5-yrs) erosion rates can be close to 100-ft/yr, longer term rates are influenced by the
duration of erosion in any one place. Given rapid avulsion and lateral migration processes result in relatively
short durations of channel occupation in a single place, we estimated lower long-term erosion potential rates.
Observed Valley Vegetation Groups
Mature Conifer Dominant Stands
Immature/Pioneering Trees and Shrubs
Herbaceous
Immature/pioneering trees and shrubs were observed to be the dominant riparian condition within the
geomorphic migration zone. Where large, mature trees were observed in riparian areas, erosion rates appeared
lower, concurring with other research (Abbe et al. 2003, Abbe and Brooks 2011). Mature forest’s deeper, denser
root mass creates increased soil cohesion and roughness which reduce erodibility. We observed that where
large trees were recruited to the channel, they were relatively stable and influenced channel migration
processes (Figure 3, 3b). In contrast, immature/pioneering trees and shrub zones are recruited regularly to the
channel and were observed to provide little erosion resistance and had shallow rooting that was often undercut
by lateral erosion (Figure 3b). Immature/pioneering trees and shrubs recruited to the channel appear to have
transported downstream and did not directly influence channel migration processes. Herbaceous vegetation
offered the least erosion resistance and bank cohesion due to limited root depths. Erosion rates are expected to
be higher in the herbaceous and immature/pioneering trees and shrubs riparian areas (Figure 3c, Abbe and
Brooks 2011). Abbe et al. 2016 presented two examples illustrating the influence of tree size on channel
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migration on the South Fork Hoh, one showing how the recruitment of large trees retarded erosion and initiated
new floodplain development (Figure 3d) and one showing that the lack of large trees failed to limit erosion
(Figure 3e).
Figure 3a. Photo showing relatively stable snag in river where bank erosion recruited a large tree. The snag is
deflecting flow away from the bank and helped to slow down bank erosion. Flow is from right to left (Oct. 1,
2020, at RM 18.8).
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Figure 3b. Photos illustrating importance of large trees in providing wood to the river that is capable of
altering channel hydraulics and slowing bank erosion (top photo of stable 9-ft diameter Sitka Spruce with 30-
ft rootwad in the Queets River, T. Abbe). Bottom photo showing high terrace with young trees (industrial tree
farm) where trees reaching the channel are quickly transported downstream and, consequently, don’t
contribute hydraulic roughness to the channel sufficient to slow erosion (Abbe and Brooks 2011).
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Figure 3c. Comparison of erosion rates in the Queets and Hoh Rivers as a function of tree size. Riparian areas
with trees greater than 21-in (0.53m) erode at less than half the rate of areas with trees less than 21-in (Abbe
et al. 2003, Abbe and Brooks 2011).
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Figure 3d. Example of where recruitment of large trees to the South Fork Hoh and channel response. Slides
containing mature trees not only stopped bank erosion but also built a new floodplain along the toe of the
eroded bank. From 1990 to 2006 the river migrated 106 ft into an area of mature timber. Once in the channel
the timber halted erosion and by 2013 the active channel had moved back to the south (Abbe et al. 2016).
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Figure 3e. Example of where erosion proceeded along the South Fork Hoh due to a lack of large trees. This
site is located downstream of the previous Figure. Between 1990 and 2006 the river migrated 153-ft (9.6-ft/yr)
into a clear-cut. Bank erosion triggered a landslide that extended 550 ft into the adjacent valley margin. The
landslide headscarp retreated at a rate of 24-ft/yr from 1990 to 2013 (Abbe et al. 2016).
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Figure 3f. Old growth alluvial valley in Upper Hoh, about 3.6 miles upstream from ONP Hoh Visitor Center.
Flow is from right to left. Note extensive cover of old growth across valley bottom, large number of islands
and channels, and patches of old-growth within the active channel migration zone. Small side channels extend
through much of valley bottom that aren’t visible through the forest canopy. Young deciduous forest that
occupies most of the valley bottom in areas that were logged only accounts for a relatively small portion of
the valley bottom where there was no logging. The large trees reduce the rates of channel migration and form
logjams that provide the foundations of the old-growth patches. Over millennia the recruitment of large wood
allows old-growth to colonize most of the valley bottom.
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Hazards and Risks
Hazards: To understand the potential impacts related to fluvial process hazards in the project reach, it is
necessary to define hazard and risk. Hazard is defined as the source of danger. For this analysis, the channel
migration associated hazards are:
Erosion and scour hazards
Flooding, debris impacts, and deposition hazards
Landslide/slope instability hazards
Risk: Risk is defined as the product of probability of a hazard and the consequences it will have. For example,
even if the probability of erosion reaching a home is low but the consequences are high (losing the house), the
risk is high. Risk is typically applied to human development, but it can also be applied to ecological systems. For
example, in an old-growth valley there may be high probability of bank erosion, but the consequences are
actually beneficial to habitat because of large wood recruitment. If the old-growth timber was removed from
the same valley the probability of erosion would increase dramatically and the consequences would have
significant impact to habitat by creating wider more dynamic channels with large gravel bars subject to invasive
plant colonization. Thus, removing big trees from a valley bottom poses very high risks to aquatic and riparian
habitat. Building infrastructure such as roads outside a channel migration zone lowers the probability of erosion
to zero, demonstrating why long-term planning should strive to get roads out of CMZs. The probability of flood
inundation is dependent on river flow, topography and channel conditions. Flooding risk can thus be lowered by
either moving out of flood prone areas or raising a structure. While flooding poses risks to development it is a
beneficial process to ecological communities. A chart illustrating different levels of relative risk based on
probability of occurrence and resulting consequences is presented below.
Mapping for this analysis presents areas in which erosion, scour, debris impacts, and scour related to fluvial
process may occur within a 100-yr planning horizon, incorporating changes to flow and sediment regimes
resulting from predicted climate change (IPCC 2021). No distinction of consequences from hazards is provided in
this analysis, therefore relative risk levels have not been assigned. It is our opinion that specific risk assessments,
targeted either geographically or toward a particular concern such as boater safety, would be best informed by a
more detailed analysis.
Mapping Results
The mapping assessment provides the following hazard information and is provided in Appendix D, Map 4:
Historic Migration Zone (HMZ) Mapping: The HMZ mapping in this analysis shows channel locations occurring
between 1939 and 2018. The HMZ should not be confused with a channel migration zone (CMZ). The HMZ is
simply where channels have been during historic times whereas the CMZ delineates where channels may move
in the future. Since HMZ is the area occupied by a river in recent times it is always low-lying areas of the valley –
a major attribute distinguishing it from a CMZ which can include high ground that can be eroded by the river, a
common occurrence in the Middle Hoh. As described earlier, areas with large trees erode at less than half the
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rate as areas with small trees (<21 inches in diameter), thus timber harvest can accelerate channel migration,
even into high terraces and valley margins. Current forest practices prohibit timber harvest in CMZs. Mapping of
channel locations conducted by the Bureau of Reclamation (2004) consisted of the visible wetted channel area.
The 2017-18 channel mapping consisted of the visible “high flow” channel (wetted channel plus unvegetated bar
areas) and low flow wetted channel. GPS mapping of the October 2020 channel thalweg was also included. Not
all channel locations during this historic air photo interval were captured by the air photo record, so the true
HMZ may extend beyond the mapped HMZ area. The HMZ is an area with erosion and avulsion hazards that
has a high probability of occurrence.
Active Geomorphic Migration Zone (GMZ) Mapping: The GMZ mapping was based on LiDAR interpretation,
REM surface interpretation and FEMA flood mapping. The GMZ extends beyond the HMZ and includes an area
where channel activity has recently occurred and at certain flows or with changes in channel bed elevation or
wood loading, may be reactivated and experience fluvial processes. The GMZ is an area with erosion and
avulsion hazards that has a moderate to high probability of occurrence.
100-Yr Erosion Hazard Area (EHA) Mapping: The EHA refers to an area in which erosion hazards may be realized
within the 100-yr planning horizon. The consequences of erosion hazards being realized within the designated
EHA have not been determined for this analysis, and therefore risk has not been evaluated. Structures and
infrastructure impacted by erosion hazards may be well above river water surface elevations or a long distance
from today’s current channel location. Included in the erosion hazard areas are landslides that are triggered
by lateral channel migration and expand up-gradient from the channel margin (see Geotechnical Hazard Area).
Professional opinion of erosion rates was applied. This opinion considered bank height, geologic composition
(younger alluvium, older alluvium, glacial diamicts, or bedrock), vegetation type and age. Geology type was
inferred by mapped geology, LiDAR, and field observations. The most erodible banks are low height, younger
alluvium, with grass vegetation. Short-term erosion rates in this bank type may be on the order of 100-ft/yr,
perhaps higher. Erosion rates over a 100-yr time frame must also consider the duration of time the river channel
is located at a bank. In most cases on the Hoh, channel migration processes limit the duration of time a channel
is actively eroding a bank to a few years before the channel migrates to a new location. The frequency that a
channel returns to a bank over the assessment timeframe must also be considered. For this analysis, the 100-yr
erosion rate for low banks with younger alluvium and immature or non-native vegetation was a minimum of
500-ft/yr. Bedrock banks were assumed to have a 100-yr erosion rate of 0-ft/yr. The EHA is an area with erosion
and avulsion hazards that has a lower probability of occurrence.
Avulsion Hazard Area (AHZ) Mapping: The AHZ describes an area within the HMZ and GMZ that is susceptible to
rapid channel course changes or temporary channelization of flow that would become an erosion hazard. While
erosion hazards are often realized incrementally and avoidance or retreat is an option to manage risk, avulsion
hazards may be realized abruptly and potentially catastrophically, thereby potentially increasing consequences
and decreasing viability of avoidance or retreat management strategies. Avulsions are common on the Hoh
River, thus exacerbating risk. Once a relict channel is reclaimed in an avulsion, rapid lateral erosion and channel
widening of the new channel results. Over the course of the 100-yr planning horizon of this delineation, the GMZ
can be considered synonymous with the AHZ, as any of the relic channels defining the GMZ could pose an
avulsion risk over time as the channel migrates. Therefore, the AHZ is not specifically identified in the
delineation.
Geotechnical Hazard Setback Area (GHA) Mapping: The GHA mapped area has potential slope instability driven
by channel migration processes. For this study the fluvial-related geotechnical hazards are considered if the 100-
yr EHA contacts steep slopes. The GHA is shown as an overlay on the maps. Site specific geotechnical conditions
should be considered for risk analyses within the GHA. The GHA is an area with erosion and landslide hazards
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that has a low to high probability of occurrence based on the location of the channel relative to the mapped
GHA.
Alluvial Fan Hazard Areas (AFH) Mapping: The AFH defines an area where a sharp decrease in channel slope
causes a wedge of sediment to deposit as stream energy is rapidly lost, creating a characteristic fan shape in
plan view. Alluvial fans are common at the margins of valley bottoms and are highly dynamic environments
prone to rapid channel avulsions and aggradation. The AFH has the potential to be an erosion hazard,
aggradation hazard, flooding hazard and/or debris impact hazard or any combination thereof and may change
over time as the fan evolves. The AFH is an area with erosion, aggradation, flooding, and debris impact hazards
that has a high probability of occurrence based on the high energy of the environment.
Channel Migration Zone (CMZ) Mapping: The cumulative area and hazards associated with the HMZ, GMZ, EHA
and GHA areas define the extent of the CMZ.
Summary and Conclusion
The Middle Hoh is a dynamic landscape that has undergone historic disturbances that have altered and limited
natural processes, and faces a future of additional changes that will further alter natural processes. Historic
clearing of the riparian forests altered the rate of channel migration in the reach, making the river more dynamic
and less predictable. Future climate changes will alter the flow regime, sediment supply and transport capacity
of the river, with the potential to fundamentally change the character of the river. Given the uncertainty in what
changes will occur and when they will be realized we recommend planning conservatively, as the past is
becoming less and less a predictor of what to is to come. An example of this is show in Figure 4, where the river
had migrated beyond the 2004 CMZ delineation in 2006, continuing to erode through 2018 expanding 100-ft
past the boundary. As the river continues to adjust to future changes in sediment supply, land use, vegetation
cover, and the timing and magnitude of flooding, we can expect the river to occupy and flood areas that have
been safe since early homesteading. Planning ahead and adaptative management strategies are key to
mitigating risks resulting from future channel migration and increased peak flows.
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Figure 4. Comparison of Bureau of Reclamation 2004 mapping to updated mapping conditions and revised
methodologies. Image at left is 2004 channel location mapping (colored ribbons) and channel migration zone
(black hatched zone). Image at right is updated channel mapping with historic migration zone (red),
geomorphic migration zone (dark orange), erosion hazard area (light orange) and geotechnical setback (yellow), all included in the updated CMZ limit (black boundary). Note that the current channel is outside of
the 2004 delineated channel migration zone.
Limitations
Limitations of this analysis include:
Mapping scale – temporal and spatial: The mapping efforts for this analysis were done on a reach scale.
Site-specific investigation may be necessary. Site-specific investigations and validation of mapping was
conducted only sparingly because of a limitation of time and resources.
Temporal changes, disturbances, or recovering conditions, such as riparian development or wood jams,
are variables that will impact channel response. Predicting the local response and impacts over the time
scale of the study is not considered feasible because of the unpredictable nature, time scale, and extent
of change. For example, predicting the location of the channel, size and duration of a wood jam, and
riparian conditions at a site even in 5-yrs is felt to have a low degree of assurance. Analysis looking at a
smaller timeframe context and a more site-specific or sub-reach perspective should include such
conditions and potential channel response.
New information and technology – new interpretations: Improvements in technology, new information
and geologic interpretations may allow for a higher confidence in mapping or reinterpretation of
mapped hazards. Maps should be updated as new information and technology becomes available.
Hazards that exist but were not mapped for this assessment: The hazards mapped for this analysis were
limited to lateral erosion and avulsion potential on the Hoh River. Other natural hazards in the valley
exist, including but not limited to flooding, landslides, tectonic deformation.
Riparian and Floodplain Native Forests
The Hoh River valley floodplains, terraces and adjacent hillslopes within Olympic National Park are the home of
the extraordinary Olympic rain forest, including riparian forest four to seven hundred years old (Fonda 1974;).
The Middle Hoh River floodplain is predominantly second and third growth forest and recently established red
alder. Remnant patches of mature forest hundreds of years old comprise just 1,271-ac, approximately 24% of its
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former extent. The Olympic rain forest provides few limits to forest growth and old growth trees reach
diameters of 6 – 10-ft and up to 260 – 300-fts in height (Fonda 1974; Kramer et al., 2020). The structural size and
complexity of the primordial Hoh River riparian forest provides the river with in-channel large wood that the
river hydraulically sorts into stable wood jams forming the structural skeleton of river channel splits, mid-
channel islands and patchwork floodplains (Montgomery and Abbe 2006).
The numerous gravel bars present in the Middle Hoh River floodplain are nursery sites for establishment of
herbaceous and woody plants. Typically, young riparian forest consists of early successional willows (Salix L.),
red alder (Alnus rubra), and black cottonwood (Populus balsamifera ssp. trichocarpa). As the young pioneer
forest matures (25 – 50-yrs), incipient soil development allows conifers to also colonize the floodplain–primarily
Sitka spruce (Picea sitchensis)–with minor elements of western hemlock (Tsuga heterophylla), Douglas fir
(Pseudotsuga menziesii) and western red cedar (Thuja plicata). Later colonizers include deciduous trees–vine
maple (Acer circinatum) and big leaf maple (Acer macrophyllum). As the riparian forest matures over 50 – 100-
yrs, Sitka spruce and black cottonwood reach key member size diameters of 3-ft or more. Circa 100-yrs, and
older, the riparian forest becomes the source pool for recruitment of large trees to the river channel in a
phenomenon called the floodplain large wood cycle (Collins et al. 2012). The floodplain large wood cycle is the
natural process that generates Hoh River channel complexity wherever mature conifer floodplain forests
predominate; mid-channel islands, pools, salmon aquatic habitat and overall valley complexity and habitat
diversity.
An essential foundation of Hoh River’s diverse geomorphology and aquatic and riparian habitats is the
preponderance of mature conifer forests, the occasional exceptionally large trees and the ecological processes
that generate these trees. The interaction of abundant precipitation, temperate climate, rapid tree growth, and
geology produce the wide range of habitat types that favor Hoh River salmon and steelhead productivity, and
thriving populations of bear, cougar, osprey, eagle, and a myriad of other creatures.
The goal of the Middle Hoh River riparian forest study was to characterize the current riparian forest
composition, structure and trends to inform development of a forest conservation and restoration and
conservation strategy. Key findings include: (1) the Hoh River valley riparian forest was largely cut during the
20th century, (2) inside and outside the CMZ only 24% of the area is in mature conifer deciduous forest >125-ft
tall, (3) young deciduous forest < 75-ft tall dominates 41% of the study area, and (4) riparian key member sized
trees (≥5-ft diameter), available for channel recruitment, are significantly reduced in number compared to
historic or reference conditions.
Methods & Study Area
Forest Mapping & Characterization
The Middle Hoh River study area includes river floodplains and terraces along the riparian corridor from Olympic
National Park to Highway 101. Riparian forest mapping was conducted in a GIS (ArcMap) environment using
2015 NAIP imagery and a 2014 first return LiDAR digital surface model (DSM). The first return LiDAR DEM
provides a mapped measurement of vegetation height (Figure 5). The NAIP color imagery allows mapping of
coarse scale monotypic forest stands. Forests were typed in three cover classes and four height classes (Figure 6,
Figure 7 & Figure 8). Cover classes included: (1) > 75% cover deciduous trees (willow, red alder, black
cottonwood, big leaf maple, and vine maple; (2) > 75% cover conifers (Sitka spruce, Douglas fir, western hemlock
and western red cedar); and cleared land (pasture, development); and (3) mixed conifer deciduous (<75%
deciduous & <75% conifers). Five height classes were measured with the LiDAR DEM: <5-ft, <25-ft, 25-75-ft, 75-
125-ft, and >125-ft.
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Figure 5. First return 2014 LiDAR DEM of forest vegetation heights at South Fork confluence with main stem
Hoh River. Olympic National Park is clearly delineated by the much higher tree heights.
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Figure 6. Middle Hoh River riparian forest type cover and height classes.
Figure 7. Hoh River riparian forest mosaic of cover types. October 1st, 2020, near RM 20.6
Forest Mapping Typology
1
Forest
Deciduous
>75% Cover
Mixed <75% Cover
Conifer & Deciduous
Coniferous
>75% Cover
Pasture, cleared forest
Notes:
Forest height in feet
Minimum mapping size: 0.5 acres
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Figure 8. Forest typing and channel migration zone (CMZ).
Results & Discussion
The Middle Hoh River riparian forest was mapped within and outside the CMZ to capture channel disturbance
dynamics within the CMZ as compared with older terrace and adjacent hillslope surface processes (Appendix D,
Map 5, Figure 6). The Hoh River CMZ riparian forest, as mapped, is a mosaic of patches of young pioneer red
alder flats to mature mixed conifer deciduous forest stands Table(Figure 9, Figure 10& Figure 11; Table 1. Inside
the CMZ. Forest type and height class.). Channel migration, through erosion and sedimentation, generates new
surfaces that are colonized by willows, red alder and black cottonwood. As the forest matures, within 25-yrs,
conifer colonization begins in earnest and these trees will grow to maturity over hundreds of years, unless
harvested or succumbing to a natural disturbance such as erosion by the main stem river, as yet unexperienced
climate extremes, major wildfire or wind events, or competition by invasive species.
Deciduous forest (red alder, willow, black cottonwood) makes up 41% of the CMZ cover types, all of which are
<125-ft in height, descriptive of young to mature red alder floodplain forests less than 80-yrs (Table 1). Mixed
conifer deciduous type comprises 32% of the total CMZ forest cover (Table 1). Together the deciduous and
mixed cover types total 73% of the entire CMZ forest cover, while coniferous cover type comprises 19% of the
total CMZ forest (Table 1). The height structure of the riparian forest generally reflects age, with shorter trees
being younger and taller trees older. The >125-ft coniferous and mixed classes comprise 24% of the total forest
cover, while <75-ft classes comprise 44%. This height distribution is reflective of a younger CMZ red alder
dominated forest with patches of mature conifer and mixed conifer deciduous stands dispersed throughout.
Within the CMZ past timber harvest has led to diminished floodplain roughness and to an accelerated channel
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disturbance regime, the primary control of existing riparian forest composition and structure. The loss of large
key member size trees, and stable wood jams that generate mid-channel islands and stable floodplain surfaces,
results in a loss of refugia sites for mature floodplain forests to develop (Montgomery and Abbe 2006).
Acknowledging the key role of mature riparian forests in providing in-channel aquatic habitat, Washington
Forest Practice regulations limit the number of harvestable trees within the Riparian Management Zone (WAC
222-30-021).
Wind in the coastal Pacific Northwest also plays a role in structuring mature forest stands outside the CMZ
where forest cover is dominated by Mixed (44%) and Coniferous (33%) cover types (Figure 12; Table 2).
Deciduous forest makes up only 16% of the total non-CMZ cover as compared to CMZ’s 41%. Forest stands
>125-ft comprise 25% of the total forest cover indicating forest stands reaching a century in age. Extensive
deforestation is the primary driver of forest type and structure both within and outside the CMZ. However,
changes in forest practices allow for forests to regrow in the CMZ where channel migration rates are conducive
to long-term growth. Unfortunately, a threshold appears to have been reached where floodplain stability
continues to decline and regrowth of large trees is likely limited to sites with large stable log jams accumulated
over years with rare “key pieces” of in channel wood where erosion has locally claimed exceptional trees, and
also in areas protected by human interventions such as the placement of rip rap. Outside the CMZ clearing,
timber operations and development continue to drive forest type and structure. The implication of these
findings for the Hoh River resiliency strategy is that the existing mature conifer and deciduous riparian forests
need protection, and new floodplain refugia sites need to be strategically re-created in a manner that protects
them from main stem channel erosion.
Given climate change projections for the next century the Olympic peninsula forest will likely have an increase in
fire frequency and experience more frequently periods of heat stress (Halofsky et al. 2011). In the Olympic
peninsula river valley forests, a changing climate over the next century is not likely to change the species
composition, however, individual trees more adapted to the changing climate will be at a selective advantage as
compared to those that are not as resilient. In the face of these increased temperature projections foresters
throughout North America have begun to develop new seed transfer guidelines for forestry replanting
operations (Kilkenny et. al. 2013). Seed transfer guidelines are developed from genecological garden plot studies
throughout the region located at various latitudinal and longitudinal positions allowing assessment of which tree
ecotypes are most favorable across a species range and projected climatic conditions. The new seed transfer
zones will form the basis of assisted migration efforts to meet the challenges of our changing climate. Indeed,
this ongoing research will result in new sets of seed transfer zones for the Olympic peninsula that will be
important in selecting climate adapted tree ecotypes for reforestation operations. Although the coastal Olympic
peninsula riparian forests are more resilient than the upland forests they will be impacted as the overall climate
continues to warm. The results of forestry genecological studies will be forthcoming over the next decade
informing forest restoration efforts in the Hoh River valley.
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Figure 9. Young deciduous (red alder and willow) and older mixed conifer deciduous (red alder and Sitka
spruce) forest types. October 1, 2020, near RM 20.6. Note logjam proximity to larger conifer patch.
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Figure 10. Mature mixed (Black cottonwood, red alder, Sitka spruce) and conifer forest types (Sitka spruce,
Douglas fir). Right bank (flow from right to left), October 1, 2020, near RM 20.7.
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Figure 11. Inside CMZ. Riparian Forest Type (Ac) and Height Class (Ft/Ac).
Table 1. Inside the CMZ. Forest type and height class.
HEIGHT (FT) CLEARED (AC) CONIFEROUS
(AC)
DECIDUOUS
(AC)
MIXED
(AC)
GRAND
TOTAL (AC)
<25 165 16 76 257
25-75 116 476 142 734
75-125 28 362 334 725
>125 272 260 532
Grand Total 165 432 914 737 2248
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Figure 12. Outside CMZ. Riparian Forest Type (Ac) and Height Class (Ft/Ac).
Table 2. Outside the CMZ. Forest classes and types.
HEIGHT (FT) CLEARED (AC) CONIFEROUS
(AC)
DECIDUOUS
(AC)
MIXED
(AC)
GRAND TOTAL
(AC)
<25 222 175 67 44 507
25-75 162 287 311 760
75-125 277 91 632 1000
>125 376 24 339 739
Grand Total 222 990 468 1325 3006
Hydrology & Hydraulics
A hydraulic model of the Middle Hoh River was developed using Hydronia’s RiverFlow-2D Plus GPU and Aquaveo
SMS v13.0 computer software. RiverFlow-2D is a two-dimensional finite volume computer model that provides
depth averaged hydraulic parameters at centroids within a triangular mesh model domain. The model domain
encompasses 15-RM, with the upper boundaries on the Hoh River and the South Fork Hoh River upstream of the
National Park boundary, and the lower boundary just downstream of the Highway 101 bridge.
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Hydrology and Boundary Conditions
To develop estimated inflows for the Middle Hoh River model, NSD performed a hydrologic analysis of the
region. This analysis focused on two USGS gages: USGS gage #12041200, Hoh River at US Highway 101 near
Forks, WA (henceforth referred to as the Highway 101 gage) and USGS gage #12041000, Hoh River near Forks,
WA (henceforth referred to as the upstream gage). The downstream gage’s period of record is 1960-2021, but
the upstream gage was retired in 1964, though it has data all the way back to 1921. Since the model domain is
so large, both gages were analyzed to help determine model hydrology. NSD performed a flow frequency
analysis on both gages using the Log-Pearson schedule 3b methodology (USGS 1981), the results of which are
shown in Table 3.
Table 3. Estimated peak flows at each gage in the model domain.
USGS GAGE DRAINAGE AREA (SQ MI) 1-YR FLOOD (CFS) 2-YR FLOOD (CFS) 10-YR FLOOD (CFS) 100-YR FLOOD (CFS)
# 12041200 (Highway 101 gage) 253 12,260 32,700 52,300 73,600
# 12041000 (Upstream gage) 208 8,190 19,000 30,800 46,000
The model was run for a series of three representative flow scenarios – the 1-yr, 10-yr, and 100-yr floods – to
evaluate hydraulic parameters at the project site. There were 10 inflow locations to this model – their locations
are illustrated in Figure 13. The magnitude of all modeled flows at each of 10 inflow locations is shown in Table
4.
The main stem inflow was determined using the peak flow analysis of the upstream gage, scaled by drainage
area to the main stem inflow location using the weighted USGS scaling method presented in Mastin et al 2016.
Discharge at the remaining inflow locations was determined using Streamstats where available, and when
Streamstats was not available the discharge was calculated using the USGS regional regression equations.
Because only the 9 largest tributaries were explicitly modeled, the flow contributed by several smaller
tributaries as well as seepage and hillslope runoff within the model domain needed to be accounted for. This
additional flow to the model discharge is needed to approximate the 10-yr and 100-yr peak flows estimated
from the downstream gage. This was achieved by adding a small amount of additional discharge to each inflow
location proportional to its drainage area. For the 1-yr flood, the inflows were reduced in proportion to their
drainage area to achieve the same goal. For each inflow location, the model inflow which has been adjusted to
account for hillslope runoff is shown Figure 13, Table 4.
The models were run in a steady-state (constant discharge) and have only one outflow boundary located just
downstream of the Highway 101 bridge and the downstream gage. The outflow boundary condition was set to a
constant water surface elevation (WSE) corresponding to each flow event. These WSEs were based on analysis
of the rating curve of the Highway 101 gage. Downstream WSE was set to 175.03, 185.53, and 189.81 for the 1-
yr flood, 10-yr flood, and 100-yr flood respectively.
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Figure 13. Locations of model inflow and outflow locations illustrated over the model domain.
Table 4. Modeled Discharge Values at Inflow Locations
INFLOW
LOCATION
DRAINAGE AREA
(SQ MI)
1-YR 10-YR 100-YR
Hoh River 124.9 7,700 27,200 35,900
SF Hoh River 53.8 4,080 13,900 17,700
Winfield
Creek 11.6
60 2,100 3,950
Clear Creek 6.9 20 480 880
Maple Creek 9.5 100 1,480 2,620
Owl Creek 2.4 200 2,200 3,760
Hell Roaring
Creek 5.5
30 1,020 1,920
Alder Creek 8.3 90 1,670 3,050
Tower Creek 4.5 - 1,140 1,920
Spruce Creek 4.5 - 1,140 1,920
Total 12,280 52,330 73,620
Highway 101
Gage
Estimate
12,260 52,300 73,600
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Mesh Development and Roughness Categories
The topographic data was developed by combining information from LiDAR data collected in 2012 and 2013, as
well as bathymetry data that was provided by Wild Fish Conservancy from a 2013 survey. The model mesh was
created with fine mesh spacing in the main channel and in floodplain channels, with expanded mesh spacing in
less topographically complex areas further from the stream.
Hydraulic resistance is characterized in the model by polygons representing differing surface roughness types
such as main stem channel, forest, or bare earth. The full list of roughness categories and their associated
Manning’s n values is included in the calibration section in Table 5. Due to the large domain of this model,
roughness categories were assigned in as automated a fashion as possible. First, to attain a base of vegetation
roughness, NSD subtracted the bare earth LiDAR from the highest hit LiDAR to attain a 15-ft x 15-ft raster of
vegetation height split into five categories: <1’, 1-4’, 4’-6’, 6’-12’, and >12’. To map roads onto this vegetation
base, the lines in the DNR roads shapefile were given a 10’ width and overlaid. The locations of the roads were
spot-checked against aerial imagery to confirm their accuracy; when discrepancies were identified, the road
locations were edited to reflect aerial imagery. The low flow channel was then delineated using a wetted
perimeter polygon derived from the combined surface, and on top of that the tributaries, side channels, and
logjam roughness areas were manually delineated using 2013 aerial imagery.
Modeled Infrastructure
NSD identified five road crossings that are directly engaged by the Middle Hoh River or by the modeled
tributaries: 3 near the Clear Creek confluence, one upstream of the Clear Creek confluence, and one on Spruce
Creek before the confluence with the main stem. At these locations, NSD modeled the road crossings using the
Riverflow2D culvert tool, which accounts for culvert shape, size, material, slope, and inlet configuration using
the FHWA procedure (Norman et al. 1985). Details on the three culverts near Clear Creek were provided by the
10,000 Years Institute from field observation; details on the two remaining culverts were estimated based on
the surrounding LiDAR data.
Calibration
The 2D model was calibrated by comparing the modeled 100-yr inundation area to the digitized FEMA base
flood map, effective June 7, 2019, and adjusting the model to bring it as close to the FEMA floodplain as
possible. The main tools available to calibrate the 2D model were adjusting the hydraulic roughness parameters
using the Manning roughness coefficient (n-value) for various land cover types. Initial values were set for the
roughness coefficients based on recommended values from previous studies and professional judgement. After
the initial run, results were compared with the FEMA base flood and minor adjustments were made to optimize
calibration. Final calibrated roughness values are shown in Table 5.
Appendix D, Map 6 includes a series of maps comparing the calibrated model to the FEMA floodplain. The areas
in which the two do not agree can be explained by differences in tributary modeling – for instance at small
tributaries where the model does not include a specific inflow, the FEMA floodplain shows more inundation than
the model, and conversely where tributary inflows were inflated to account for surrounding drainage area, the
FEMA floodplain shows less inundation than the model. The focus in calibration was on flooding related to main
stem flow.
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Table 5. Calibrated Manning's n roughness values for each roughness category.
CATEGORY MANNING'S N VALUE
Veg <1' 0.04
Vegetation 1'-4' 0.07
Vegetation 4'-6' 0.08
Vegetation 6'-12' 0.08
Vegetation >12' 0.1
Road 0.016
Building 0.5
Active Channel 0.035
Tributary 0.045
Revetment 0.1
Results
Maps of hydraulic model results for depth, velocity, and shear stress during the 1-yr, the 10-yr, and the 100-yr
floods are included in Appendix D, Map 6. The depth and velocity results were spatially separated based on
location in the floodplain vs. the active channel and then summarized for each of five reaches within the model
domain. The resulting depth and velocity averages are shown in Table 6 and Table 7, respectively.
Table 6. Average depth by reach for the modeled peak floods.
AREA FLOOD EVENT
MEAN DEPTH (FT)
HUELSDONK-
SOUTH FORK
REACH
SPRUCE
CANYON
REACH
MORGAN’S
CROSSING
REACH
WILLOUGHBY
CREEK REACH
OXBOW
CANYON REACH
Channel 1-yr 4.4 7.3 5.1 4.6 8.5
10-yr 6.9 15.8 8.7 8.9 19.8
100-yr 7.9 19.0 9.9 11.5 24.2
Floodplain 1-yr 2.6 3.9 3.1 3.1 5.0
10-yr 3.7 6.6 3.6 5.2 10.0
100-yr 4.3 8.2 4.3 7.6 12.2
Table 7. Average velocity by reach for the modeled peak floods.
AREA FLOOD
EVENT
MEAN VELOCITY (FPS)
HUELSDONK-SOUTH FORK REACH
SPRUCE CANYON REACH
MORGAN’S CROSSING REACH
WILLOUGHBY
CREEK REACH
OXBOW
CANYON REACH
Channel 1-yr 5.1 8.0 5.6 4.8 7.4
10-yr 6.9 12.3 7.7 5.9 12.4
100-yr 7.4 13.2 8.3 5.9 13.8
Floodplain 1-yr 2.9 4.0 3.2 3.2 3.8
10-yr 3.6 3.7 2.8 2.3 4.7
100-yr 3.9 3.7 3.1 2.3 4.9
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The average depth in the main stem ranges from 4.4-8.5-ft in the 1-yr event, 6.9 - 19.8-ft in the 10-yr event, and
7.9 - 24.2-ft in the 100-yr event. The range of average depth at high flows is large due to the geomorphic
differences between the reaches: the main stem is tightly confined in Oxbow Canyon reach and part of Spruce
Canyon reach, resulting in high depths compared to the other reaches like Huelsdonk-South Fork reach, where
flow is spread out across the floodplain
The average velocity in the main stem ranges from 4.8 - 8.0-ft per second (fps) in the 1-yr event, 5.9 - 12.4-fps
during the 10-yr event, and 5.9 - 13.8-fps in the 100-yr event. Floodplain velocities remain in the range of 2.3 -
4.9-fps regardless of flood event recurrence interval. As with depth, the highest main stem velocities are in the
confined reaches while the lower velocities are associated with reaches where flow can overtop the banks and
engage the floodplain.
Oxbow Canyon Reach
Flow conditions in the Oxbow Canyon Reach are the deepest on average for the entire 15-mi project reach due
to near complete confinement of flow in the channel up to the 100-yr flood (Table 6). Velocities rival those
found in Spruce Canyon with the greatest average velocities in Spruce Canyon during the 1-yr flood,
transitioning to Oxbow Canyon as flows approach and exceed the 10-yr flood. A small floodplain is present on
the right bank downstream of RM 17, and backwater eddy at RM 16 on the left bank that provide high flow
refugia within the canyon during floods exceeding the 5 – 10-yr flood (Appendix D, Map 6).
Willoughby Creek Reach
Upstream of the Oxbow Canyon Reach the floodplain abruptly widens and flows begin to spread out as the
channel traverses the Willoughby Creek Reach. At the downstream end of the reach, as the channel enters
Oxbow Canyon, a backwater forms that rapidly floods the adjacent floodplain and diminishes instream
velocities. The influence of this backwater propagates upstream with increasing flow, extends over a mile
upstream during the 100-yr flood, and influences instream and off-channel flow velocities and depths (Appendix
D, Map 6). The effect of this backwater also explains the lack of an increase in the average channel velocity from
the 10-yr to the 100-yr flood (Table 6).
During the 1-yr flood side channels are activated in the Elk Creek Floodplain area as well as 2.1-mi long side
channel following the valley margin on the left bank floodplain from Peterson’s Bottom to Elk Creek. Velocities
in the main stem channel are greatest where the channel is a single thread and diminish rapidly as the channel
bifurcates in more and more channels (Appendix D, Map 6).
Morgan’s Crossing Reach
The Morgan’s Crossing Reach extends from Peterson Bottom to the downstream end of Spruce Canyon and is
naturally unconfined with a broad floodplain through the entire reach. Downstream of Rock Creek the channel
bifurcates into multiple threads during the 1-yr flood and floodplain side channels are activated in the Lindner
and Clear Creek floodplains. A backwater extends approximately 2000-ft up an abandoned main stem channel at
the Rock Creek confluence, upstream of which flow is confined to the main stem channel to the upstream end of
the reach.
As flows increase to the 10-yr flood, water exits the channel banks and there is broad inundation of floodplains
throughout the reach (Appendix D, Map 6). Between RM 21 – 22.6 overbank flooding crosses the Upper Hoh
Road near Lindner Creek Lane during the 10-yr flood and continues downstream north of the road following a
historic side channel down to Lindner Creek, crossing the road back to the channel next to the Peak 6 Adventure
Store. When flow approaches the 100-yr flood the length of the Upper Hoh Road inundated increases and
extends up to the Morgan’s Crossing floodplain below the Tower Creek confluence.
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Spruce Canyon Reach
The shortest reach in the Middle Hoh is the Spruce Canyon Reach, starting below the Owl Creek confluence at
Spruce Island, ending at the downstream end of Spruce Canyon. Flows in the Spruce Canyon are similar in nature
to that of Oxbow Canyon, the biggest difference being flows are in general deeper in Oxbow Canyon. The
channel is confined to the bedrock canyon throughout the reach, minus the split around Spruce Island at the
upstream end of the reach. Overall, the Spruce Canyon Reach has the highest average velocity in the Middle Hoh
for more frequent high flows less that the 10-yr flood. Near the 10-yr flood overbank flow enters an off-channel
habitat pond (Dismal Pond, WDFW) constructed from a gravel pit on the right bank floodplain at the upstream
end of the reach, exiting the other side and continuing downstream on the floodplain to the Spruce Canyon inlet
(Appendix D, Map 6).
Huelsdonk-South Fork Reach
At the upstream end of the Middle Hoh is the Huelsdonk-South Fork Reach, extending from Spruce Island to
ONP. Average channel flow depths in this reach are the lowest of all reaches and are the shallowest or close to
on the floodplains (Table 6). Velocities are consistently second lowest for all flows, behind the Willoughby Creek
Reach (dampened velocity due to backwater above Oxbow Canyon).
The main stem channel flows unconfined through the reach, meandering across the valley bottom at low flows.
As flows increase historic main stem flow paths begin to activate forming large islands that remain dry during
the 1-yr flood, short of a few side channels traversing the islands (Appendix D, Map 6). With increasing flow, the
islands and adjacent floodplains become submerged but do not flood the Upper Hoh Road. The channel has
however expanded into private property in the Brandeberry and Fletcher Ranch areas, eroding land and
damaging or engulfing structures in the process. The main stem channel through this reach has been actively
avulsing and migrating in recent history, frequently adjusting the nature of hydraulics in the reach. The
topographic surface available for this modeling does not represent the current condition, however predicted
flow characteristics in the channel and floodplain are anticipated to be similar. The location of the main stem
channel will dictate where high velocity areas are located, and recent avulsions and bank erosion will expand the
area inundated and increase flow depths.
Main Stem Aquatic Habitat
The goal of this habitat assessment is to quantify and qualify the current habitat conditions of the main stem
Hoh river, including braid, side, and main channel habitats and to describe their use by salmon populations in
order to evaluate the current habitat available and to identify impairments and restoration opportunities.
The Hoh River hosts five salmon species, including populations of spring and fall Chinook Oncorhynchus
tshawytscha, fall coho O. kisutch, and winter steelhead O. mykiss (McHenry et al. 1996). The Hoh River salmon
stocks are not listed under the Endangered Species Act (ESA) and are considered to be among the last healthy
wild populations in the contiguous United States, however recent declines in adult returns have been
documented (Huntington et al. 1994; Hoh Tribe 2016; Cram et al. 2018). The runs of interest differ in their
timing and use of riverine habitats, but Chinook, coho, and steelhead all rely on the main stem Hoh for both
rearing and spawning (McHenry 2001; McMillan and Starr 2008). Salmon spawning occurs in the main stem
throughout the year, but the timing depends on the species. Spring Chinook generally spawn in August and
September, fall Chinook and coho spawn from October through December, and winter steelhead spawn from
December through July (McMillan and Starr 2008). These species also utilize the main stem habitat differently as
juveniles. Most fall Chinook and many spring Chinook out-migrate at age-0, while coho, steelhead, spring
Chinook may overwinter and remain in the river for a full year. Coho and steelhead are also documented to use
more lateral main stem (braids and side channels) and tributary habitats during rearing than Chinook, which
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primarily rely on main channels of the main stem (McMillan and Starr 2008; Quinn 2018). However, all species
are documented to use braid and side channels for spawning.
Adequate freshwater migration, spawning, incubation, and rearing habitat is important for all these species
(Quinn 2018). All three species require suitable sized gravel and cobble for spawning and rearing with low levels
of fine sediment. Winter rainfalls and the resulting flooding can exacerbate erosion and landslides, scour and
damage redds, and increase infiltration of fine sediment reducing oxygen levels available to embryos, which in
turn decreases the chance of survival to emergence (Quinn 2018). Furthermore, overwinter rearing habitat is
particularly important for juvenile coho, steelhead, and to an extent spring Chinook due to their extended stay
in freshwater compared to fall Chinook. Lack of adequate summer flows, water quality and temperatures,
channel complexity, slow water habitat, and off-channel and floodplain connectivity can contribute to low
salmon rearing and spawning success (Ames et al. 2000; Hoh Tribe 2016).
While the status of salmon stocks in the Hoh River are generally considered to be healthy, declines over the past
two decades have prompted cause for evaluation (Smith 2003; Hoh Tribe 2016). The Middle Hoh has been
impacted by the loss of riparian old growth forest and reduction of large wood inputs, erosion, landslides and
increased fine sediment pulses, and decreased water quality (Parks 1999; Hoh Tribe 2016). Additionally dramatic
channel migration has occurred within the study area in recent years, with movements of over 60-ft a year
(Chadd 1997; Piety 2004; Hoh Tribe 2016) and local landowners and the county are concerned about the loss of
property and road infrastructure, as well as the impacts on salmon and instream habitat quality. In the below
summary, we characterize the summer low flow (i.e., average daily flow of 1,614 to 2,652 cfs at the Highway 101
bridge (USGS Gage 12041200) main stem aquatic habitat conditions as surveyed from September 28th to
October 1st, 2020, from RM 16 to 31, including channel conditions, habitat quantities, and bank conditions.
Methods
Low flow habitat surveys on the Hoh River main stem were completed by Cramer Fish Sciences (CFS) from
upstream of the Highway 101 Bridge (RM 15-16) to the National Park Boundary (RM 30-31) from September
28th to October 1st (Figure 14). Average daily flows during the surveys ranged from 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200; Figure 15). All main channel watercourses were surveyed; and braid
and side channels were surveyed as time allowed to achieve a representative subsample of the habitat quality
and quantity (Leopold and Wolman 1957; Peterson and Reid 1984). Wetted side channels and braids that were
unable to be surveyed because of access or time constraints were captured at their diversion point from the
main channel with photos and GPS coordinates.
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Figure 14. Overview of the Hoh River survey area with survey reaches of interest (Piety et al. 2004) and start
and end of survey locations.
Figure 15. Instantaneous flow (cfs) data at USGS Gage 12041200 – Hoh River at Highway 101 near Forks, WA
recorded and reported by USGS. Surveys were conducted between September 28th and October 1st, 2020.
Main stem surveys were completed moving downstream by boat. Reaches were determined by geomorphic
characteristics (Piety et al. 2004). Channel type was recorded as main, braid, or side channel; main channels of
the main stem were identified as channels with the most flow; braids were identified as one or more
anastomosing channels connected to the main channel, and side channels identified as channels within the main
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stem floodplain separated by islands with stable woody vegetation (Leopold and Wolman 1957; Peterson and
Reid 1984). Habitat units were identified as pools (non-turbulent), riffles (fast-turbulent), or glides (fast non-
turbulent) (Bisson et al. 1982; Beechie et al. 2005; CHaMP 2016). Pool type (e.g., plunge, scour, dam) and pool-
forming feature were recorded for pool units (Bisson et al. 1982). Pool frequency was calculated as the pools per
mile of channel length and pool spacing (channel widths per pool) was calculated using the Montgomery et al.
(1995) formula as the channel length per wetted channel width (Wc) divided by the number of pools. Pool
frequency targets were identified using NMFS (1996) (Table 8). Note that while the number of pools per mile
goes down in larger channels, when normalized by channel width, pool frequency (#/Wc) increases as channel
size increases. Lengths and wetted widths were recorded in meters using a laser rangefinder. We were unable to
measure depths given the survey scope and funding, as measuring depth by boat requires a sonar or depth rod,
which is difficult and time consuming in a large swift water river. All metric units were converted to English units
in processing. The GPS coordinates of the top and the bottom of each dominant unit were recorded, GPS units
were also used to record tracks of the channels surveyed. Recorded data outputs are available in Appendix A.
Table 8. Pool frequency standards for functioning rivers developed by NMFS (1996).
CHANNEL WIDTH (FT) # POOLS/MILE # pools/Wc
5 184 0.17
10 96 0.18
15 70 0.20
20 56 0.21
25 47 0.22
50 26 0.25
75 23 0.33
100 18 0.34
For each riverbank of each unit, the percent of length occupied by each edge type at the wetted edge was
estimated. Edge types were recorded as bank edge (natural or hydro-modified) or bar edge (Hayman et al.
1996). Hydro-modified banks were identified as banks where modifications were visually observed, such as
levees or riprap, however the quality was not recorded. If banks were modified but the modification could not
be identified, they were categorized as “Hydro-modified unknown.” Bar edges were assumed to be naturally
formed (Hayman et al. 1996). The width of slow water was recorded if present for each edge type. Slow water
area was defined as present when a boundary between the edge type and mid-channel was visible as a current
shear line; slow water edge width was assumed to be a minimum of 1-m wide for all banks.
Large wood jams (LWJs) were mapped using aerial photography collected in March 2021 (NV5 GeoSpatial 2021;
Figure 16). The average daily flow during collection was 3,366 cfs at the Highway 101 bridge (USGS Gage
12041200; Figure 17). We digitized all jams visible within the bankfull channel, including wood visible in the
water, on gravel bars, and on vegetated islands. All jams composed of three or more wood pieces 7.6 m in
length by 0.3 m in diameter were manually delineated using QGIS at a zoom level of 1:600 or higher, and the full
perimeter of the jam was recorded (Leif et al. 2004). The location of the jam in the main stem (main channel and
braids, side channel, or islands), the channel location (bar, bank, or island), and whether the jam was wet or dry
were recorded for each jam. Jam locations were also recorded during field surveys, however, considerable
channel movement led to changes in jam positions and areas, therefore all reported jam metrics are from the
aerial imagery analysis.
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Figure 16. Example of jams delineated in the Morgan’s Crossing Reach (RM 21.9), shown at a 1:600 scale using
aerial photography collected in March 2021 (NV5 GeoSpatial 2021). Blue polygons depict wood in wetted
channel (time of photo) and red polygons wood outside wetted channel but within ordinary high water
(bankfull) channel. Flow is from right to left.
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Figure 17. Instantaneous flow (cfs) data at USGS Gage 12041200 – Hoh River at Highway 101 near Forks, WA
recorded and reported by USGS. Aerial imagery was collected on March 20th, 2021.
Results
A total of 28.8 linear miles of wetted main stem habitat were surveyed in the Middle Hoh River Study Area from
RM 16, at the Oxbow Campground to RM 31 at the National Park boundary (Appendix A, Appendix D, Map 7).
This included 15.8 miles of main channel, 8.0 miles of braided channel, and 4.9 miles of side-channel habitat.
Wetted braids and side channels were present in all reaches except in the Oxbow Canyon Reach (Figure 18,
Appendix D, Map 7). Additional braid and side-channel habitats wetted at the time of the survey were not
surveyed because of time constraints, however representative samples of these habitats were surveyed to
qualify the habitat present. Braid and side-channel habitat was the most abundant in the Huelsdonk-South Fork
Reach, followed by the Morgan’s Crossing Reach (Appendix D, Map 7).
Overall, glides were the dominant habitat unit with 48% of the surveyed wetted channel area observed in glide
units followed by riffles and rapids which made up 31% of the surveyed wetted channel area, and pools and
backwater units, which accounted for the remaining 21% of wetted channel area (Figure 18, Appendix D, Map
7). It should be noted, that because we were unable to measure depths and calculate residual depths, pools
were identified by the presence of channel (e.g.., confluences, channel bends, bedrock canyons) and large wood
features or changes in surface flow and hydrology (i.e., the presence of slow water), and therefore pools may
have been classified as glides and underestimated if no visual clues were present. However, slow water edge
area was also documented, as slow water edge habitats are more utilized by juvenile salmon in large rivers than
main channels (Beechie et al. 2005). Riffles and rapids were the most frequently observed units, with eight units
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per mile, followed by pools and backwater units (six units per mile), and glides (five units per mile). Of the
reaches surveyed, the Huelsdonk-South Fork Reach had the highest total number of pools, total area in pools,
and the highest pool frequency (pools per mile), but also had the most channel length surveyed (Appendix A).
The Spruce Canyon Reach had the fewest pools and lowest pool frequency (pools per mile).
Trench, scour, and backwater pool units were observed (Figure 18). Trench pools were formed by bedrock and
canyon features and were primarily observed in the Oxbow Canyon Reach (Figure 19). Large wood frequency
was not significantly correlated to pool frequency across the reaches but there was a slight trend indicating that
there was a positive relationship between LWJ frequency and pool frequency. This is expected because LW can
drive pool formation, however in the main channel, meanders were the primary pool forming features, followed
by bedrock features. We observed that many jams provided edge cover in summer low flow conditions but were
not large enough to drive pool formation in the main channel.
The majority of bank habitat in the Hoh main stem was made up of bar edges (55% of edge length) and natural
bank edges (42% of edge length) (Appendix A, Table 4). However, hydro-modifications including rip rap, roads,
and other bank armoring and residential bank modifications were documented in all reaches except the Oxbow
Canyon (Figure 18). Rip rap and bank armoring were most prevalent in the Huelsdonk-South Fork Reach, with
1.3 miles of hydro-modified banks present over ten locations, followed by the Willoughby Creek Reach with 0.8
miles of hydro-modified banks present over five locations (Appendix A, Table 4). Slow water edge areas
associated with natural bank edges are important rearing habitats for juvenile salmon, especially age-0 and age-
1 steelhead during winter flows (Beamer et al. 2005; Beechie et al. 2005). Bar edges are also used by rearing
salmon, but densities are lower in these habitats due to their slightly higher velocities and tendency to have less
cover than natural bank edges (Beechie et al 2005). Rip rap and diked banks have been documented to have
reduced slow water area and lower Chinook and steelhead densities (Schmetterling et al. 2001), however a
study in the Hoh River observed that these habitats can support comparable densities to LWJ, if they create
cover and complex habitat (Peters et al. 2012). Studies have suggested that rearing salmon density is correlated
to the area and velocity of slow water present (Beechie et al. 2005; Peters et al. 2012), we observed bar edges
and natural bank edges to have the greatest associated average slow water edge width (4.1-ft) and total area,
followed by hydro-modified bank edges (3.7-ft).
Wood was mapped using aerial imagery collected six months after the low flow habitat surveys, during which
three flow events over 20,000 cfs occurred leading to multiple changes in the channel form. Wood values are
reported as they were observed in the March 2021 aerial imagery, however, the field data recorded in the low
flow 2020 habitat surveys suggest trends in wood distribution were consistent between the surveys. The
majority (87%) of the 2,573,637-ft2 of mapped LWJ area was located in the main channel and braids, followed by
side channels and forested islands. Of the total LWJs mapped in the main channel, 54% were dry on bars, 28%
were wetted and on bars, 11% were wetted and bank attached, and 7% were dry and bank attached (Appendix
A). In side channels and on islands, 31% of the jams were dry on bars, 25% were wet and bank attached, 28%
were wet and bar attached, 18% were dry on islands, and 8% were dry on bars. While the majority of the LWJs
mapped were dry, LWJs with some wetted area accounted for most of the mapped area and the mean wetted
jam size was approximately twice as large as the dry (Appendix A, Table 6). The Huelsdonk-South Fork Reach
contained the most LWJs and total overall, wetted, and dry LWJ area, but the Morgan’s Crossing Reach had the
highest LWJ frequency (LWJ/mi) (Appendix A, Table 7). The mean and median LWJ sizes were above the full
study area value (5,066-ft2 and 2,813-ft2, respectively) in the Huelsdonk-South Fork, Spruce Canyon, and
Morgan’s Crossing reaches (Appendix A, Table 7). Jam sizes were smaller than the study area average in the
Willoughby Creek and Oxbow Canyon reaches, likely due to the fact that majority of large wood transport from
the ONP would be racked in the upstream reaches (Welber et al. 2013; Kramer and Wohl 2017) and the riparian
area within the study area is dominated by deciduous and second-growth conifer forests. While wood was not
the primary driver of pool formation in the main channel and wood sizes have decreased in the last century as a
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result of logging, the large wood present drives the generation of slow water edge habitat and eddies and
provides cover for rearing salmon in the main channel (Peters et al. 2012). Additionally, wood cover is generally
thought to be essential for predator avoidance for rearing salmon, but it has been observed to be less so in
turbid rivers where visibility is already limited (Peters et al. 2012). The LWJ size was larger relative to the channel
wetted width in side channels, which drove the formation of the majority of mapped pools, this indicates that
more complex rearing habitat is available in side channels for steelhead, coho, and spring Chinook (Sedell 1982).
The Huelsdonk-South Fork Reach, Morgan’s Crossing Reach, and Willoughby Creek Reach contained the most
braid and side-channel habitat, though the confinement of the Spruce Canyon Reach and Oxbow Canyon Reach
was driven by natural canyon features and not infrastructure encroachment. Hydro-modified banks were
infrequent throughout the study area as a whole. However, the Upper Hoh Road flanks the right bank of the
main stem and is directly adjacent to the river in the Huelsdonk-South Fork Reach, Morgan’s Crossing Reach, and
Willoughby Creek Reach. Rocky bank armoring and rip rap was documented along the road without vegetative
cover during the summer low flow surveys and presents an opportunity for enhancement and roughening to
improve the habitat. Additionally, the main stem is eroding multiple residential properties in the Huelsdonk-
South Fork Reach.
Substrate was visually characterized throughout the study area and was largely gravel and cobble dominated,
with numerous high-quality spawning habitats in riffles and pool tails. However, substrate was not characterized
at the unit level and this effort did not include mapping spawning habitat or redds. Future efforts aimed at
incorporating this information would be informative for identifying adult salmon use throughout the reaches
(Montgomery et al. 1999). Several landslides and eroding banks were observed throughout the reaches, which
could lead to fine sediment pulses during heavy rainfall events (Hoh Tribe 2016). However, fines were not visible
as the dominant sediment in any of the reaches at the time of survey during low flow conditions.
The reaches of the Middle Hoh Study Area generally represent high quality salmon habitat, with abundant braid
and side-channel habitat, a large number of pools and slow water glides and edges, and frequent large wood
(17.6 jams/mile). Pool frequencies were below reported targets for both main channels (over 100-ft in wetted
width), for which the National Marine Fisheries Service (NMFS) considers 18 pools per mile to be adequate, and
braids and side channels (wetted width of 25 – 50-ft), for which NMFS has a target of 47 pools per mile (NMFS
1996; Table 8), however, there was a large amount of slow water edge habitat observed, both with wood cover
and without, and a large number of slow water glide habitats that would provide rearing and holding habitat for
juvenile and adult migrating salmon, respectively. Actions to emulate the large trees that once were common in
the valley are needed to increase the number of stable logjams. While the Hoh River has a large amount of
wood, the vast majority is mobile and has limited function in forming stable logjams that persist over time. This
is necessary not only to sustain pool frequency over time, but more importantly to sustain side channels and
allow mature conifer patches to develop that can sustain the large wood cycle (Abbe and Montgomery 1996;
Collins et al. 2012; Abbe et al. 2016).
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Figure 18. Overview of the Middle Hoh River Study Area with the results from the CFS habitat surveys
conducted from September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the
Highway 101 bridge (USGS Gage 12041200). For more detailed mapping see Appendix D, Map 7. Braids and
side channels were surveyed as time allowed and were not a full census. Main stem diversion locations of un-
surveyed wetted braids and side channels were identified during surveys and general channel locations were
mapped using the aerial imagery in GIS.
Oxbow Canyon Reach
The Oxbow Canyon Reach is the downstream extent of the study area and was surveyed from the Oxbow
Campground near RM 16 to downstream of RM 17.5 at the confluence of Winfield Creek and the main stem Hoh
River (Figure 19). The reach is heavily confined by a natural canyon that prevents lateral channel migration. No
braided channels were wetted at the time of survey and no side channels were present in this reach (Appendix
A). Glides were the dominant habitat unit in this reach, and accounted for 49% of the wetted channel area,
followed by pools, which accounted for 28% of the wetted channel area (Figure 19). One rapid and four riffles
were also observed, accounting for the remaining 23% of surveyed wetted channel area. Natural bank edges
made up 69% of the edge length in this reach, while bar edges made up the remaining 31%. No hydro-modified
bank edges were present in this reach. The average slow water edge width for both natural bank edges and bar
edges was 4.1-ft (Figure 19).
The Oxbow Canyon Reach had the lowest main channel pool spacing (8.5 channel widths per pool) and highest
main channel pool frequency (4.2 pools per mile) of the reaches surveyed, with eight pools observed in the 1.9
miles of channel length (Appendix A, Table 5). There were seven trench pools and one scour pool documented in
this reach, all of which were formed by bedrock features (Figure 20).
Wood was infrequent in this reach, with only two wetted jams and no dry jams mapped (Appendix A, Table 6).
Large wood jams were relatively small in this reach, with an average jam size of 2,270-ft2 (Appendix A, Table 7).
However, given the confinement and bedrock present in this reach, opportunities for natural wood racking and
accumulation are minimal.
Given the confined nature of this reach, the presence of bedrock and boulders, and the lack of off channel
habitats, this reach likely serves as a migratory corridor rather than rearing or spawning habitat for juvenile and
adult Chinook, steelhead, and coho (Figure 19). The reach contains numerous deep pools and boulders which
provide year-round holding habitat for the upstream migration of adults and out-migration of juveniles. The lack
of side channels in this reach suggests that this reach would not be used heavily for rearing for juvenile spring
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steelhead, coho, or Chinook. Additional large wood placement would not benefit this reach as pool formation
was driven entirely by bedrock.
Figure 19. Overview of the Oxbow Canyon Reach with results from CFS habitat surveys from September 28th
to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the Highway 101 bridge (USGS Gage
12041200). No wetted braid or side-channel habitat was present in this reach. The mapped photo is shown in
Figure 20.
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Figure 20. An example of the bedrock banks present in Oxbow Canyon (location of image shown in Figure 19).
The canyon confines the channel and prevents the formation of off-channel habitat; therefore the reach would be primarily used as a migration corridor for salmon.
Willoughby Creek Reach
The Willoughby Creek Reach extends from RM 17.5 at the Winfield Creek confluence with the main stem up to
upstream of Willoughby Creek near RM 20.5 (Figure 18; Figure 21). The Upper Hoh Road flanks the right bank of
the main channel at the upper extent of the reach. The Willoughby Creek Reach is a relatively unconfined
sinuous gravel-cobble reach. Near the middle of the reach, the main channel demonstrates substantial
migration, and has shifted over the last 30-yrs away from a large meander bend on the left bank to a more linear
channel form. The lower extent of the reach is more naturally confined and exhibits less migration.
There were 3.3 miles of main channels, 1.9 miles of braided channel, and 0.5 miles of side-channel habitat
surveyed in this reach. Two additional braided networks and two additional side-channel networks were
observed as connected to the main channel the time of survey but were not surveyed due to time constraints
(Figure 21). Glides were the dominant main channel unit in in this reach and accounted for 58% of the wetted
channel area (Appendix A). Riffles and rapids made up 32% and 1% of the wetted main channel area,
respectively. Pools were infrequent in the main channel and only accounted for 9% of the total wetted main
channel area.
Pools were more frequent in braid and side-channel habitats and made up 25% and 40% of wetted channel area,
respectively (Figure 21). Glides made up 47% and 31% of braid and side-channel wetted habitat area,
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respectively, and riffles made up the remaining 28% of channel area for both braids and side channels. The
additional braided channels present were observed to be glide and riffle dominated. Given the ephemeral
nature of braids in alluvial channels, these habitats would be impacted by winter floods.
Main stem edges were primarily composed of bar edges, which made up 63% of the surveyed edge length. Bank
edges made up the other 37% of main channel length, of which 18% were hydro-modified (Appendix A). The
Willoughby Creek Reach had the second highest total length of hydro-modified bank edges after the Huelsdonk-
South Fork Reach of the reaches surveyed (Figure 18). Two areas on the river right bank were noted to have
substantial erosion and trees actively sloughing into the channel (Figure 22). Most of the slow water edge area
observed was associated with bar edges, however, slow water edge width was the greatest in natural bank
edges, with an average slow water edge width of 4.1-ft, followed by bar edges, with an average edge width of
3.6-ft (Appendix A). Hydro-modified bank edges had an average slow water edge area of 3.3-ft (Figure 22).
Total percent pool area and pool frequency were low and pool spacing was high in this reach compared to other
reaches, with only 13% pool area, 1.5 pools per mile, and 21.8 channel widths per pool (Appendix A, Table 5).
Twenty-eight pools were documented in the 5.7 miles of channel length surveyed in this reach. Large wood jams
and pieces were the primary pool forming feature, followed by channel features, including meanders and
confluences (Figure 21).
The Willoughby Creek Reach contained the highest LW frequency for wet jams and second highest overall.
However, the median jam size was smaller than other reaches at 2,685-ft2, and the reach had the third lowest
total jam area (Appendix A, Table 7). The majority of jams were located in the main channel on gravel bars (97
jams comprising 377,247-ft2), while only 16 bank-attached jams were mapped totaling 47,564-ft2 of area
(Appendix A, Table 6). Jams in this reach were smaller than the upstream Huelsdonk-South Fork and Morgan’s
Crossing reaches, which suggests the larger old growth conifers entering the system from Spruce Flats/Island
and ONP are being deposited in the upstream reaches (Welber et al. 2013; Kramer and Wohl 2017) and the
wood inputs to the Willoughby Reach are primarily from the deciduous and second-growth conifer trees located
in the Middle Hoh Study Area riparian.
Pool frequency and total pool area was low compared to other reaches and to NMFS targets (NMFS 1996; Table
8). However, slow water estimates that include glide habitat and slow water edge areas suggest that there is
abundant habitat in this reach for juvenile rearing and adult holding for coho, steelhead, and spring and fall
Chinook (Appendix A). Additionally, there were numerous off channel habitats for rearing coho, steelhead, and
spring Chinook and spawning coho, steelhead, and Chinook in this reach.
The jam size in this reach is smaller than the study area average, which is likely a result of and a facilitator to the
high degree of channel migration during winter and spring floods. Chinook, steelhead, and coho redds may be at
risk of scour during these large channel migration events and the impact of scour on egg-to-fry survival should
be evaluated in future studies (Roni et al. 2016). Fall Chinook, coho, and steelhead, would be particularly
impacted by potential scour events as fry would not yet have emerged by spring floods (Montgomery et al.
1999). This reach contained abundant gravel throughout, which suggests suitable spawning conditions for adult
Chinook, steelhead, and to a lesser extent coho in the main channel if redds are buried below the scour line
(Montgomery et al. 1999). Additionally, side channels and the tributary confluences were also noted to contain
gravel, which would provide spawning habitat more protected from scour events.
The abundance of wood in this reach, the presence of numerous off channel habitats and large confluence side
channels and tributaries within the main stem floodplain (e.g., the Elk Creek Confluence Side Channel), and the
large area of slow water edge and main channel habitats suggests that this reach would provide abundant
habitat for juvenile steelhead and coho overwinter rearing, and juvenile spring and fall Chinook rearing and out-
migration (Figure 21; Beechie et al. 2005). Wood in side channels was frequently observed to be channel
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spanning and pool forming, creating slow water habitat area and providing cover to rearing salmon (Figure 22).
Additionally, it is presumed that the terrace-tributary Elk Creek Confluence Side Channel provides relatively
stable habitat (less impacted by channel migration) that would provide high quality rearing and spawning
habitat in this reach (Sedell et al. 1982).
Restoration efforts in this reach should target the 0.8 miles of road that runs along the right bank of the main
stem (Figure 22), which would benefit from enhancement actions such as raising the road prism and protecting
the bank toe with large wood structures to create a more natural hillslope form and increase bank attached
wood jam area to create slow water main channel habitat and provide shading and predator protection.
Western Federal Lands Highway Division, in partnership with Jefferson County, completed construction of a log-
dolo revetment at the upstream end of the reach in 2021 to replace the riprap along the road. Additional actions
aimed at protecting riparian forests with the long-term goal of establishing forests similar to those in the ONP
and planting meander bends with conifers to increase roughness would also benefit this reach.
Figure 21. Overview of the Willoughby Creek Reach with results from CFS habitat surveys from September
28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the Highway 101 bridge (USGS Gage
12041200). Braids and side channels were surveyed as a representative subset of the habitat available as time
allowed and were not a full census. Two side channel networks and two braided areas, shown in gray, were
documented as connected to the main channel at the time of the surveys but were not surveyed due to time
constraints. Photos are shown in Figure 22.
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Figure 22. Reach photos with locations shown in Figure 21. 1) An example of a large stretch of eroding banks
with immature industrial forest observed which demonstrates inputs of fine sediment and clay and small
wood into the river. 2) A LWJ formed pool in a side channel with intermittent connectivity. 3) An eroding bank
recruiting small Douglas firs into the channel. 4) A location of rip rap where the Upper Hoh Road runs along
the right bank and constrains the channel. The riprap provides no complexity, no cover, no hydraulic refugia
and no potential for wood recruitment.
Morgan’s Crossing Reach
The Morgan’s Crossing Reach extends from RM 20.5 upstream of the Willoughby Creek confluence with the
main stem to RM 25.5 (Figure 18). The Upper Hoh Road runs adjacent to this reach and confines the floodplain
on the right bank. The road runs directly adjacent to the main channel right bank at the downstream and
upstream end of this reach and flanks the right bank of a side channel in the middle of the reach. A substantial
amount of channel migration has occurred in the middle of this reach, with the channel straightening and
moving away from the road on the right bank. Most of the sinuosity in this reach occurs in the middle extent,
with minimal braid and side-channel habitat or main channel meandering occurring in the upstream and
downstream ends of the reach. The Morgan’s Crossing Reach was the longest reach surveyed and represents
important spawning and rearing habitat for Chinook and coho and steelhead, respectively in both the main
channel and off-channel and tributary habitats.
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A total of 7.7 miles of wetted main stem channel length was mapped in the reach, including 4.8 miles of main
channel, 1.8 miles of braided channel, and 1.1 miles of side-channel length (Appendix A). The majority of the
Lindner side channel complex was wetted during the low flow surveys but was not surveyed due to time
constraints and difficulty accessing deep non-wadeable or boatable channels, however a representative sub-
section was surveyed (Figure 23). Three additional braid complexes were not surveyed due to time constraints,
these habitats appeared consistent with the braid complexes that were surveyed. Glides accounted for
approximately 60% of the total wetted channel area, followed by riffles which made up 31%, pools which made
up 9%, and backwater units that made up 1% (Appendix A). This reach had the lowest main channel percent
pool area, and second lowest total pool channel area.
Pools accounted for more wetted channel area in braids and side channels than in the main channel in this
reach. In braids, glides accounted for 46% of wetted channel area, riffles accounted for 28% of wetted channel
area, and pools accounted for 26% of wetted channel area. In side channels, pools accounted for 60% of the
wetted channel area, followed by glides which made up 22% of wetted channel area, and riffles which made up
18% of wetted channel area (Figure 23).
Approximately 60% of the total edge length was bar edges, 38% was natural bank edges, and 2% of banks were
hydro-modified (Figure 23). Bank hydro-modifications, including rip rap and residential development, were only
documented in main channels in this reach, however, a road also runs along the Lindner side channel and
confines lateral movement on the right bank (Figure 23; Appendix D, Map 7). The average slow water edge
width 4.1-ft for bar edges, 3.9-ft for hydro-modified bank edges, and 3.6-ft for natural bank edges. Slow water
edge habitat associated with main channel bare bar edges and bar edges with LW racking provides an additional
100,000-ft2 of slow water area in addition to the pool area, which would be important low velocity habitat for
rearing steelhead, Chinook, and coho (Beechie et al. 2005).
The Morgan’s Crossing Reach had the second highest total main stem (main channels, braids, and side channels
combined) pool area of the reaches surveyed, after the Huelsdonk-South Fork Reach (Appendix A, Table 5).
While the percent pool area and pool frequency (pools per mile) in the main channel were the lowest of the
reaches surveyed, in braids and side channels, percent pool area and pool frequency were amongst the highest
of the reaches (Figure 18). Main channel pools were primarily formed by channel features, while large wood
primarily drove pool formation in braids (Figure 23). Side-channel pools were formed by both large wood and
channel features (Figure 24).
The Morgan’s Crossing Reach had the highest overall (wet and dry) LWJ frequency and second highest total LWJ
area (Appendix A, Table 7). Main channel and side channel LWJs were abundant in this reach (Appendix A, Table
6). There were 120 jams located on gravel bars, comprising 634,488-ft2 of total jam area, and 31 jams located
attached to banks, comprising 184,083-ft2 of jam area (Appendix A, Table 6). This reach had the second largest
mean jam size of the reaches surveyed (Appendix A, Table 7).
Total pool area was low in the main channel of Morgan’s Crossing Reach but there was abundant slow water
habitat in side channels for juvenile rearing and for coho, steelhead, and spring and fall Chinook spawning. The
Upper Hoh Road runs directly adjacent to this reach in multiple locations which presents an opportunity to
enhance bank habitat. Additionally, three locations along the right bank were noted to have severe erosion and
landslide risk. These locations likely provide pulses of fine sediment and clay after storm, but further evaluation
is needed to understand their impact on egg-to-fry and rearing salmon survival (Figure 24). Bank enhancement
actions such as raising the road prism, planting, and placing large wood benefit salmon, by roughening banks
and providing cover, and help to protect infrastructure. Floodplain plantings of conifers in the larger alder groves
on older bars and meander bends could speed up riparian succession and provide bank stabilization. This reach
would also benefit from continued floodplain forest protection to encourage the establishment of mature
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conifer forests, similar to those present in the ONP, to provide long-term large wood inputs to create large
functional jams and stabilize the channel.
The Morgan’s Crossing Reach contains the Lindner Side Channel, which is a large and important side channel
complex for juvenile salmon. In the subset of the Lindner Side Channel surveyed, we observed abundant pool-
riffle habitat, which provides high quality spawning substrate and slow-water refuges for adult and juvenile
salmon, respectively. One large jam was present in the surveyed extent of the Lindner Side Channel, which
would provide cover for rearing Chinook, steelhead, and coho. Additionally, vegetated natural bank edges were
prevalent in this reach, which also provide slow water habitat with cover. There was little evidence of recent
channel migration in the surveyed extent of Lindner Side Channel, suggesting that the side channel is relatively
resistant to recent winter flooding and scour events. Wood frequency (jams per mile) was lower in the Lindner
Side Channel than many of the other side channels surveyed, which may limit cover for coho and steelhead
(Figure 23; Figure 24). Cover in the Lindner Side Channel would be especially important since the side channel
appeared less turbid the main channel during the low flow surveys, meaning juveniles would be more at risk to
predators with the absence of other vegetative or wood cover.
Figure 23. Overview of the Morgan’s Crossing Reach with results from CFS habitat surveys from September
28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the Highway 101 bridge (USGS Gage
12041200). The Lindner side channel is the dashed line between photo points 4 and 1. The photo was taken in
the winter (leaf off) so deciduous trees stand out as light brown areas compared to green areas of conifer
forest. The current valley bottom is dominated by small deciduous trees. Prior to logging of the valley the
number and size of large conifer patches or “islands” would have been much greater. Braids and side channels
were surveyed as a representative subset of the habitat available as time allowed and were not a full census.
One side channel complex and three braided areas, shown in gray, were documented as connected to the
main channel at the time of the surveys but were not surveyed due to time constraints. Photos are shown in
Figure 24.
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Figure 24. Reach photos with locations shown in Figure 23. 1) A long pool with ample vegetation cover but
lacking large wood jams in lower portion of Lindner Side Channel. 2) The remnants of a landslide that has
begun to be colonized by Red Alder. 3) Another landslide that appears to be actively depositing silt and clay
into the channel but is protected by a large wood jam. 4) A log jam that runs along the bank at the Lindner
Side Channel inlet along the main stem (2020).
Spruce Canyon Reach
The Spruce Canyon Reach runs from approximately RM 25.5 to RM 27 and is the shortest reach in the Middle
Hoh Study Area (Figure 18; Appendix D, Map 7). The left bank is confined by the valley wall, and the right bank is
confined by intermittent bedrock and boulders. This reach experiences little channel migration, and the channel
is largely confined to the main channel with little braid or side-channel habitat present, apart from one side
channel in the upper extent.
We surveyed 1.7 miles of main channel and 0.1 miles of braided channel length in the Spruce Canyon Reach
(Appendix A). One additional small side-channel complex was wetted at the time of survey but was not surveyed
due to time constraints (Figure 25). Pools accounted for approximately 33% of the surveyed wetted channel
area, followed by glides, riffles, and rapids, which accounted for 29%, 20% and 17% of the surveyed wetted
channel area, respectively (Figure 18; Figure 26). A long section of rapids ran upstream and into the canyon, and
one rapid spanning 472-ft and made up all of the surveyed braided channel. Natural bank edges accounted for
78% of the total edge length surveyed in this reach and bar edges made up 20% (Figure 26). One section of rip
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rap was present on river right that made up the other 2% of the edge length. Natural bank edges had an average
slow water edge width of 5.4-ft, followed by bar edges which had an average slow water width of 5.2-ft (Figure
25). The rip rap bank section had a slow water edge width of 3.3-ft. Slow water edge habitat was minimal in this
reach for riffle and rapid units and these features would likely be avoided by rearing coho and steelhead.
Total LWJ area and frequency were low in this reach, with only 15 jams mapped, however, the mean and
median wetted jam size in this reach was the highest of the reaches surveyed (Appendix A, Table 7). This was
caused by the presence of six large bank-attached wetted LWJs at upstream end of the reach, upstream of the
canyon. Minimal gravel bar habitat was present downstream in the canyon which prevented natural LWJ
accumulation (Appendix A, Table 6).
Four pools were observed in the Spruce Canyon Reach, including three pools formed by channel features and
one formed by bedrock (Figure 25 and Figure 26). The main channel of the Spruce Canyon Reach had the highest
percent pool area, though pool frequency and pool spacing were lower and higher than other reaches,
respectively (Figure 18). This reach is largely confined by natural features and presents little opportunity for
restoration. Given the presence of bedrock throughout the reach, there is not much of an opportunity for wood
recruitment, however, management actions to protect the floodplain forest in the upper extent of the reach,
upstream of the canyon to establish large conifers would increase long-term large wood inputs.
Spruce Canyon is largely confined, lacks off-channel habitat and is dominated by bedrock and boulders,
indicating it likely serves as a migratory corridor rather than rearing or spawning habitat for juvenile and adult
salmon (Figure 26). This reach contains a long pool that runs through most of the canyon which would provide
year-round holding habitat for the upstream migration of adults and out-migration of juveniles.
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Figure 25. Overview of the Spruce Canyon Reach with results from CFS habitat surveys from September 28th
to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the Highway 101 bridge (USGS Gage
12041200). Braids and side channels were surveyed as time allowed and were not a full census. Two side
channel networks, shown in gray, were documented as connected to the main channel at the time of the
surveys but were not surveyed due to time constraints. The mapped photo is shown in Figure 26.
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Figure 26. Example of a pool in Spruce Canyon with remnant pilings along the left bank. The canyon confines
the channel and prevents the formation of off-channel habitat, and therefore would primarily be used as a
migration corridor for salmon.
Huelsdonk-South Fork Reach
The Huelsdonk-South Fork Reach extends from RM 27 to RM 30.5 below the confluence of the South Fork Hoh
River and National Park Boundary (Figure 18; Appendix D, Map 7). The Huelsdonk-South Fork Reach is a
meandering and unconfined reach with abundant braid and side-channel habitat. The Upper Hoh Road runs
along the main channel Hoh in two places in this reach on right bank. Multiple residential properties exist on the
left bank and various armoring techniques were present that attempt to confine lateral movement and reduce
erosion. The reach has experienced substantial lateral channel movement in the recent years and the main stem
migration zone has widened considerably (Figure 28). Two side channels were observed, one of which was
surveyed that appeared to recently be the path of the main channel, demonstrated by the presence of large
open gravel bars and dispersed LWJs throughout. Two of the side channels, including the Lewis Homestead Side
Channel Complex appeared to be more stable with more confined bankfull and wetted channels.
We surveyed 4.1 miles of main channel, 4.2 miles of braided channel, and 3.4 miles of side channels in the
Huelsdonk-South Fork Reach (Appendix A). All wetted braided channels connected to the main channel at the
time of survey were surveyed, however, one large side-channel complex was wetted at the time of survey but
was not surveyed due to time constraints (Figure 27). In main channels of the main stem, glides were the
predominant habitat type and accounted for 43% of the total wetted habitat area, followed by pools and riffles
which accounted for 30% and 27%, respectively (Figure 18). In braided channels, riffles accounted for 46% of the
wetted channel area, followed by glides, pools, and backwaters, which made up 27%, 26%, and 1% of the wetted
habitat area, respectively. In side channels, pools accounted for 37% of the total wetted channel area, followed
by riffles and glides, which accounted for the other 32% and 31% of the wetted channel area, respectively.
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Edge habitat in the Huelsdonk-South Fork Reach was primarily made up of natural banks and bar edges,
however, the Huelsdonk-South Fork Reach had the most hydro-modified edge length of the reaches surveyed
(Appendix A). Right bank modifications included rip rap along the Upper Hoh Road, and left bank modifications
included bank armoring to protect residential property and an active erosion zone along the Huelsdonk
Property. Hydro-modified banks mostly occurred along the main channel of the main stem. The average slow
water edge width associated with bar edges was 4.3-ft. Natural bank edges and hydro-modified bank edges had
average slow water edge widths of 4.1 and 3.9-ft, respectively.
The Huelsdonk-South Fork Reach had the most total pool area (325,878-ft2) of the reaches surveyed (Appendix
A, Table 5). The total percent main channel pool area in this reach was the highest of the reaches surveyed,
however, main channel pool frequency was low with only 3.2 pools per mile (Figure 18; Table 8). Pools were
abundant in braids and side channels; 44 and 40 pools were documented in braided channels and side channels,
respectively. Channel features, including meanders and confluences, were main pool forming features in main
channel pools, but large wood jams and pieces drove pool formation in braids and side channels (Figure 28).
There were 223 LWJs mapped in the Huelsdonk-South Fork Reach, accounting for 1,170,159-ft2 of jam area,
which was the largest total area of the mapped reaches (Appendix A, Table 7). The reach also contained the
largest amount side channel and island total LWJ area (Appendix A, Table 6). The Huelsdonk-South Fork Reach
contained the largest jam mapped in the study area; however, the median jam size was smaller than the Spruce
Canyon and Morgan’s Crossing reaches (Appendix A, Table 7). The large total number and area of jams in this
reach is likely due to the proximity to the ONP, which provides a source of large old growth conifers to the river,
as well as the abundant gravel bar and roughened bank habitat present to rack large wood accumulations
(Figure 28).
While pool frequency was low in this reach, pool area was high, and the abundance of braid and side-channel
habitat provides abundant off-channel slow water habitat for juvenile salmon rearing and refuge. Cobbles and
gravels were the dominant substrate throughout the reach, which suggests adequate spawning habitat for coho,
Chinook, and steelhead. The Huelsdonk-South Fork Reach contains the most private property in the channel
migration zone of the reaches surveyed and had multiple zones of erosion that are concerning both for their
impacts on private property and as sources of sediment and infrastructure debris into the river which could lead
to fine sediment pulses and scour which could damage Chinook, coho, and steelhead redds downstream,
additionally fine sediment and clay can have negative impacts on rearing salmon. The large wood present in this
reach does not appear to deter channel movement, which also scours and damage redds (Montgomery et al.
1999). The main stem is also very wide across most of this reach and a large amount of shallow glide and riffle
habitat without cover was present (Figure 28). Even though slow water edge habitat widths were wider than
other reaches for natural bank and bar edges, these large shallow expanses represent a potential risk to juvenile
steelhead and coho rearing by increasing risk to predation. They also represent large expanses of the reach that
the lack cool deep slow water area that is preferred by steelhead, in particular (Beechie et al. 2005).
Side channels in this reach contained a high pool frequency (37%) and would be the preferred rearing habitat of
coho, steelhead, and spring Chinook. Cover, from large wood and overhanging vegetation was observed
throughout the side channels that would create complex habitat for feeding and predator evasion (Figure 28).
Due to the more moderated flows in side channels, they have more stable substrate. They also tend to have a
higher frequency of pools and habitat diversity. For these reasons side channels can provide preferred spawning
in large river valleys. Since they are also associated with floodplain wetlands and slower velocities during peak
flows, side channels are crucial rearing habitat. Logjams can be the dominate mechanism in forming and
sustaining side channels (Abbe and Montgomery 1996, 2003), and the presence of large trees in
riparian/floodplain forests is critical in the formation of logjams (Abbe and Montgomery 1996, Collins et al.
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2012). These linkages demonstrate that critical salmon habitat (side channels) in large alluvial rivers is closely
linked to riparian forests and wood.
Restoration actions, such as raising the road prism, planting, and placing large wood, aimed at enhancing the 0.4
miles of the Upper Hoh Road, which runs adjacent to the main stem of this reach in two locations, would
provide cover and create slow water habitat for salmon as well as protect infrastructure. Additionally, floodplain
fencing and other bank stabilization methods, including planting, could serve to prevent further erosion in the
short-term. Numerous alder forested islands and meander bends were present in this reach, which present an
opportunity for conifer planting to speed up riparian succession and establish stable riparian forests. Lastly, this
reach appears to have the most floodplain potential and relic side channels could be identified for reoccupation
to reduce pressure on priority banks, however, further assessment would be needed to assess the feasibility of
this restoration action.
Figure 27. Overview of the Huelsdonk-South Fork Reach with results from CFS habitat surveys from
September 28th to October 1st, 2020, at an average daily flow of 1,614 to 2,652 cfs at the Highway 101 bridge
(USGS Gage 12041200). Braids and side channels were surveyed as a representative subset of the habitat
available as time allowed and were not a full census. Only one side channel, shown in gray, was documented
as connected to the main channel at the time of the surveys but was not surveyed due to time constraints.
Photos are shown in Figure 28.
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Figure 28. Reach photos with locations shown in Figure 27. 1) An example of a wide braided channel. 2) A side
channel with alder banks and frequent channel spanning wood. 3) A side channel that departs from the main
channel with multiple root wads and vegetated banks with slow water refugia. 4) An example of a large log
jam creating edge pool habitat in the main channel.
Future Fish Habitat Survey Needs
That habitat surveys found abundant braid and side channel and main channel slow water habitat throughout
the study area with adequate gravel, which suggests there is ample habitat for juvenile Chinook, coho, and
steelhead rearing as well as adult spawning. Logging efforts over the past decades have led to a decrease in old
growth forest and thus the loss of long-term stable forested islands and a more mobile channel bed (personal
communication, Tami Pokorny), however, further studies are needed to fully understand the impacts on salmon
reproduction and survival. This survey aimed at evaluating the low flow habitat as of October 2020, with regards
to meeting salmon needs, but further surveys aimed at quantifying historical and present fish abundance and
identifying limiting factors would be beneficial to further understand the changing conditions in the Hoh River.
Additionally, evaluating egg-to-fry survival and smolt trapping efforts would be useful to understand if
overwinter survival of eggs or juvenile salmon is limiting success in the river (Roni et al. 2016).
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Anticipated Trends
Aquatic habitat in the Middle Hoh River will change and redistribute within the reach as the channel and riparian
corridor respond to changes in the flow and sediment regimes. As a result of the changing climate the channel is
anticipated to have a higher and increasing channel migration and avulsion rates due to changes in hydrology. As
these processes become more dominant it will lead to a wider channel, as mature forests are lacking along the
channel banks that could slow erosion. This wider channel, coupled with higher sediment loads associated with
receding glaciers, will increase the potential for channel aggradation and a more braided planform. The historic
loss of large trees from the Middle Hoh valley has had the most significant impacts:
increased rates of channel migration,
reduced the probability of mature forests to develop due to frequency reoccupation by river,
increased the unvegetated width of the river, increasing solar radiation and decreasing flow depths
reduced the number and lengths of stable side channels
reduced complex edge habitat
reduced stable logjams and thus number pools and forested islands (and secondary channels)
increased the valley’s exposure to invasive plants (large gravel bars and seed source from nearby timber
harvest units)
The cumulative effect of these changes will be a more simplified channel, with fewer and more shallow pools
and unstable off-channel habitat as the channel freely migrates and avulses through the floodplain. The
transition of the riparian forests to younger and more deciduous dominant will reduce local LWD inputs as the
few remaining small patches of mature timber are eroded. Fewer large trees in the channel will further reduce
the number of forced pools with cover, smaller and more few stable logjams in the channel and an overall more
simplified channel lacking hydraulic complexity.
All these changes will negatively impact habitat conditions in the Middle Hoh for salmon at the most critical
times in their entire life history: rearing and spawning. Destabilized floodplains frequently eroding cannot
provide the off channel refugia of more mature floodplains with established forests and side channel networks
connected to hyporheic flow, all needed for rearing juveniles. Diminished instream complexity reduces hydraulic
complexity and slow water refugia in the channel and the loss of large trees reduces instream cover, creating an
unhospitable main stem channel for rearing juveniles. Fewer and more shallow pools will further reduce juvenile
refugia as well as holding spots for migrating adults. Spawning adults will also find it harder to locate preferred
spawning areas as sediment will tend to segregate by size less as hydraulic complexity diminishes and riffles are
buried in sediment. Cumulatively these impacts to aquatic habitat will most impact rearing juveniles as off-
channel and instream habitats become increasingly degraded.
It is imperative to restore the large wood cycle in the Middle Hoh Valley to restore and sustain critical salmon
spawning and rearing habitat, particularly found in floodplain side channels.
Transportation
Roads have been built throughout much of the Middle Hoh River valley. The primary paved transportation
corridor, the Upper Hoh Road, provides access to Olympic National Park from State Route 101 for hundreds of
thousands of visitors each year along with the businesses that serve the tourists. A combination of gravel and
paved roads also supports logging and mining operations (primarily for road construction), farms, recreation and
residential access. The development of this road network is the result of cumulative additions over decades that
largely did not consider the many geologic hazards present nor the dynamic natural processes associated with
flooding and erosion. Maintaining vehicle access to residents, businesses, ONP and to the river is crucial to the
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local community. The current alignment of several road segments within the CMZ have chronic maintenance
issues and impair natural processes and habitat formation and creation, limiting the resiliency of the
transportation network that is relied upon while degrading habitat conditions. To improve transportation and
ecological resiliency roads planning should be a high priority. The Upper Hoh Road should be relocated outside
the Resiliency Corridor where possible. When it can’t be and is threatened by erosion, protection measures
should create complex large-scale roughness IELJs) along the bank along with a narrow buffer that can be
reforested. Unimproved roads providing river and property access within the Resiliency Corridor can be
maintained but will be at risk of washouts. Where new river access is needed it should be planned to minimize
risk by building in more stable areas less likely to flood or erode.
The purpose of this assessment is to inventory road segments vulnerable to erosion and flooding and to identify
opportunities for redesign or realignment that would improve resiliency consistent with the local community
needs and desires. Road segments (DNR 2013) were identified within the resiliency corridor, delineated CMZ
and the FEMA 100-yr floodplain in GIS and are summarized in Table 9.
Table 9. Identified road segments within the Middle Hoh CMZ, Resiliency Corridor and FEMA 100-yr
floodplain.
ROAD SEGMENTS
LENGTH IN CMZ
(MILES)
LENGTH IN
RESTORATION
OCRRIDOR (MILES)
LENGTH IN FEMA
SFHA (MI)
Unnamed 7.80 3.54 2.19
Upper Hoh Road and spurs 8.58 5.62 2.46
Old Milwaukee Rd 3.53 2.19 1.95
FR-H-1088 and spurs 1.33 0.04 -
FR-H-1009 and spurs 1.91 0.65 0.51
FR-H-1011 and spur 0.57 - -
Lewis Ponds and spur 0.58 0.14 0.09
FR-H-1062 and spurs 0.11 - -
FR-H-3700 0.06 0.00 -
FR-H-1060 0.04 - -
FR-H-3900 0.02 - -
Road Before Allen's Cutoff 0.21 0.21 -
Pit Road 0.01 - -
Hoh Oxbow Boat Launch 0.02 0.02 0.02
Minnie Peterson Campground 0.14 0.14 0.14
Grand Total 24.92 12.56 7.36
These summary tables indicate there are a number of road segments that are currently at risk from flooding
and/or erosion and that limit natural processes on the Middle Hoh. Strategies for addressing these risks and
their impact on the environment should consider the location of the segment relative to the resiliency corridor;
segments within the resiliency corridor should be prioritized for relocation or revisioning as they pose the
greatest risk to both the human and ecologic communities. Segments within the CMZ and/or FEMA 100-yr
floodplain that are outside of the resiliency corridor could consider other alternatives to limit risk to the road,
however planned relocation to a safer position on the landscape provides the greatest resiliency as local
protection typically requires maintenance and can fail.
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Opportunities for improving resiliency within the Middle Hoh through road redesign and relocation are limited
as much of the valley bottom is within the CMZ and/or FEMA 100-yr floodplain and the surrounding hillsides are
naturally unstable (Appendix D, Map 3). As such, many options need to be considered and assessed in more
detail to identify preferred alignments or, in the long-term, road alternatives. High traffic volumes and high
demand for campsites are additional sources of stress and impacts to the area landowners and properties.
During meetings with the Middle Hoh steering committee and local landowners several ideas have been brought
forward that illustrate the complexities and “out-of-the-box” thinking needed to consider current and future
risks, local and visitor access and safety, all while restoring, preserving and protecting ecologic function. Some
examples include:
Move visitor access to the Middle Hoh to the Hoh Mainline on the south side of the valley, crossing the
river at Spruce Canyon where the CMZ narrows with a new bridge. Once over the new bridge on the
north side of the river the route climbs out of the valley bottom to mid-valley slope elevations, heading
east until gradually descending back to the valley floor and joining the Upper Hoh Road east of Canyon
Creek. This alternative would improve existing roads where possible to create the new alignment, allow
decommissioning segments of road that are within the CMZ and/or FEMA 100-yr floodplain that have
been bypassed by the new road, and provide an alternative route in and out of the valley for emergency
purposes. The required bridging of the Hoh for this option would detract from ecologic resiliency as the
span would need to be within the resiliency corridor, there would be impacts to upland ecosystems
establishing and improving the new alignment, and the cost would be very high.
Relocate those segments of the Upper Hoh Road that are within the CMZ and/or FEMA 100-yr floodplain
away from the river, out of the valley bottom where necessary. New road alignments traverse terrain
with a low probability for slope failure if they ascend up the valley hillsides, subsequently descending to
rejoin the Upper Hoh Road once the relocated segment has been bypassed.
Establish alternative transportation methods for visitors to access the Middle Hoh and ONP. Creation of
a new parking area near Highway 101 and creation of a shuttle bus or 4WD service taking passengers on
the Upper Hoh Road would reduce traffic and improve safety. Building recreational trails along the river
corridor and/or through the hillsides leading up to ONP, using a similar parking area near Highway 101
would serve a similar purpose. A bike lane could be added to the Upper Hoh Road providing yet another
alternative method to access the Middle Hoh and ONP. As new technologies come online in the coming
decades, additional alternatives for moving visitors up the Middle Hoh valley will be realized that should
be considered as well. Any transportation method that does not rely on contact with or disturbance of
the ground surface would provide the least impact and provide the greatest resiliency, if not cost
prohibitive. Low-altitude aircraft requiring minimal infrastructure of take-off and landing and tunnels are
examples of technologies that are currently not developed sufficient to be cost effective but may be in
the future and should remain under consideration as implementation timelines allow.
A more complete evaluation and assessment of alternatives to improve transportation resiliency is needed to
identify a preferred solution. Alternatives need to incorporate the needs and desires of the local community,
account for potential hazards associated with the alternative while improving ecologic and community resiliency
in the Middle Hoh.
The current national trend of National Parks moving toward reservation and timed entry systems for day-use
may change transportation needs in the future, potentially changing the number of visitors to the area and
where they look to recreate. Future anticipated changes in precipitation patterns need to be included in
planning as they will alter the frequency and locations of hazards posing risk to any alternative route under
consideration. These include more extensive flooding and accelerated erosion adjacent to the river and more
frequent slope failures on steep valley margins. Site specific investigations can resolve these concerns once a
preferred alternative has been identified.
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The Hoh River Bridge on Highway 101 defining the downstream boundary of the Middle Hoh project reach was
constructed in 1931 and is a vital link in the transportation network that serves the Olympic Peninsula. The near
500-ft long span is only 20-ft wide, making for dangerous conditions as this is a major transportation route with
numerous logging trucks, motorhomes and trailers crossing every day. A replacement for this span should be
included in any planning to improve resiliency for the community as it is a vital and vulnerable piece of
infrastructure.
TRENDS & ANTICIPATED CHANGES
While the Middle Hoh River has experienced significant encroachment and manipulation, it remains relatively
wild and undeveloped. The Middle Hoh also has the benefit of the Upper Hoh River being in the largely
undisturbed and protected ONP. These factors have given the Middle Hoh River resiliency from the other
disturbances that have impacted habitat conditions, primarily logging of the floodplain forests. Even with the
loss of the old-growth forest within most of the Middle Hoh, large wood persists in the channel largely due to
inputs from the ONP. Projecting future conditions based on the best available science and observed indicators
suggests changes to the Middle Hoh are coming and should be planned for accordingly.
Climate Change
Scientific studies in the Pacific Northwest region have concluded that the frequency and magnitude of peak
flows will increase over the next 100-yrs while summer/fall low flows will diminish (Hamlet et al. 2013; Mauger
et al. 2016; Warner, Mass, and Salathé 2015; Hamlet and Lettenmaier 2007; Elsner et al. 2010, Isaak et al. 2017).
Stream flow data for the Hoh River from the USGS gage at the Highway 101 corroborate this finding of increased
peak flows and diminished low flows (Hoh Tribe 2016). Impacts from the warming climate on flooding,
vegetation, soils and the length and severity of droughts (impacting low flows) are projected are occurring and
are projected to worsen. Numerous studies for western Washington have indicated increases in peak flows as
early as the 2020s (inclusive of 2010-2039; Elsner et al. 2010, Mantua, Tohver and Hamlet 2010). Increases in
peak flows continued for model extending to the 2040s (inclusive of 2030-2059; Hamlet et al. 2013), 2050s
(inclusive of 2040-2069; Mauger et al. 2016), and beyond. The warming climate effects are therefore relevant to
the consideration of all geomorphic and hydraulic processes related to flow duration, frequency, and magnitude,
as well as forest composition, regeneration, rate of growth and risk from wildfire. Two “heat dome” events
linked to a slowing jet stream caused record heat in western Washington including the coast, as recorded at the
Quillayute Airport (106°F) and Sol Duc River (108°F) in June 2021, that led to anecdotal reports of widespread
die off of south-facing conifer limb ends and terminal bud die back on young Douglas fir.
For the Hoh River watershed, extreme variability in rainfall intensity, duration, and seasonality can be expected.
High rainfall in the watershed currently occurs primarily during the fall and winter when Pacific cyclones cause
prolonged, orographically enhanced precipitation. These storms can last for several days and are often linked to
unseasonal warmth and flooding in the Pacific Northwest. Colder temperatures at the higher elevations can lock
some of this precipitation if it falls as snow, or if the snowpack has capacity to store rainfall. If storms bring rapid
rises in freezing level from warm air, or rain falls in areas with less snowpack storage, the amount of runoff the
Hoh River receives can be dramatically higher, compounding flooding and magnifying channel responses.
The impact of the climate crisis on river dynamics in the project area were analyzed by projecting peak flow
estimates into the future based on the work done by the University of Washington Climate Impacts Group
project (Tohver et al. 2014) and are included in Table 10. Projections for increased peak flow magnitudes with
the warming climate are driven by projections for more intense precipitation, particularly in the fall and winter
months. Higher precipitation rates will increase the magnitude of annual peak and average winter flows and
contribute to increases in mass-wasting and sediment delivery to the river network, both upstream and within
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the project area. These increases in flow will expand flooding extent in the Middle Hoh and the increased
sediment loads may aggrade the channel bed, further exacerbating flooding as the channel bed and water levels
rise. The increase in annual peak flow magnitude will also contribute to increases in channel migration rates and
erosion as more flow equates to more stream energy and capacity to do work. The result of this increased
erosion will be to further limit the availability of off-channel habitats, as they will be re-worked by the river more
frequently, impacts to infrastructure will be more frequent and of greater magnitude, and private property loss
should be expected to continue without mitigating measures.
Table 10. The magnitude of future peak flows in the Hoh River for 2070-2099, projected as result of the
climate crisis under IPCC A1B scenario (broadly representing “business as usual” through 2050, IPCC 2000).
RECURRENCE INTERVAL
PRESENT DISCHARGE
ESTIMATE (CFS)
PERCENT INCREASE
DUE TO CLIMATE CHANGE
FUTURE (2070-2099)
DISCHARGE ESTIMATE (CFS)
1-yr 12,280 14 – 34% 13,975 – 16,427
10-yr 52,300 14 – 34% 58,574 – 68,850
100-yr 73,600 14 – 34% 82,140 – 96,551
The warming climate will also result in lower base flows in the late summer and fall. This will diminish the
wetted channel area and depths that will decrease available habitat. Warmer air temperatures will also result in
warmer water in the river, further stressing fish (Mantua et al., 2010; Isaak et al. 2017, Winkowski 2020) and
making riparian shade and in-stream cover even more important for salmon. While these changes were not
quantitatively evaluated by the scope of this study, they further underscore the importance of increasing the
ecological resiliency of the project area. This could be accomplished by increasing stream shade, the quantity of
off-channel habitats and deep pools, as well as increased surface water/ground water interactions through
increased floodplain connectivity and added roughness, so that the predicted increases in stream and air
temperature can be partially offset.
Sediment Sources
Sediment transport changes and trends can manifest in changes to the channel and associated geomorphic
processes, and can be divided into two general categories:
Supply Limited (leading to incision and straighter channel with lower erosion rates)
Transport Limited (leading to deposition and braided channel/wander channel forms with higher erosion
rates)
Channel forms observed in the air photo record suggest that past century sediment transport conditions and
trends are neither predominantly supply nor transport limited. The 2004 BOR hypothesizes that sediment
transport conditions were generally balanced. Field conditions identified that while the sediment supply is
robust, the Hoh River has the ability to transport this supply over time. Field observations indicated that some
localized areas are experiencing net deposition (transport limited) conditions, whereas observations at other
areas indicated that the river can be locally supply limited. Areas upstream of confined reaches, such as above
Spruce and Oxbow Canyons show evidence of sediment aggradation leading to a more dynamic channel,
whereas other areas, like below Spruce Canyon the channel is stable or degrading, due in part to confinement
from the Upper Hoh Road. We expect the general trend to be the expanding of and new aggregational areas, as
new sediment is liberated due to glacial recession and transported downstream.
The long-term trend since deglaciation (end of the Pleistocene) has been one of net supply limited conditions
which has driven incision and resulted in stranded alluvial terraces. Vertical changes in the channel can influence
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channel migration. Primary drivers in vertical changes in the channel are sediment supply, roughness, and
hydrology. Within the study reach, the net, long-term Holocene trend was incision and evidence of the
downward vertical movement of the channel is supported by the presence of numerous terraces within the
valley. The incision is controlled in part by the bedrock-lined canyons. Over time, the channel slowly incises into
the bedrock grade controls and the channel lowers. Periods of aggradation (deposition) have likely occurred
within the overall long-term incision trend. During these periods, channel migration areas would be expected to
widen. Based on the stream gradient and active erosion observed within the bedrock- controlled areas, the long-
term incision trend is likely continuing. However, this trend is very slow and channel migration processes over
the 100-yr planning horizon will be more influenced by periods of aggradation, channel widening and instability.
Rapid sediment delivery to the channel can occur from large storms, landslides, and glacial retreat associated
outwash events. These short-lived, events delivering sediment to the channel often take the form of a pulse of
sediment that may take years propagate downstream. A recent example was observed in Oxbow Canyon in June
2022 where recent landslides continue to deliver sediment and trees to the channel. Once in the fluvial system,
the sediment is temporarily stored in the channel and floodplain and periodically remobilized through scour and
lateral erosion processes, creating temporal increases in sediment load that can further supplement sediment
pulses as they migrate episodically downstream. Conversely, longer term stabilization of some sediment supply
is possible with vegetation establishment. This is true within the channel migration zone as well as in the
sediments exposed as glaciers retreat. The variability of event driven processes and the uncertainty of future
hydrologic conditions makes predicting sediment conditions problematic; however the trends point to a shift to
increased sediment loads as the climate warms, driven by more mass wasting and glacial retreat exposing and
releasing more available sediment. The fate of this sediment, where it will accumulate in the system at a given
time and the magnitude, will be a function of a number of variables that are dynamic in nature. Intermediate
and longer-term planning (5 – 25-yrs) should consider a wide range of variability in sediment loading and
transport over time. The overarching trend in the short to intermediate-term is for higher sediment loads that
could elicit a channel response in the Middle Hoh. Indicators that suggest sediment storage is growing include
an increase in the rate of avulsions, channel migration, channel braiding and an increase in flood elevations and
extent.
All aspects of geomorphic (landslides, channel avulsions, channel migration) and hydrologic response to the
changing climate will provide an advantage to non-native invasive plants, which thrive on disturbed and
nutrient-poor soils. (Naiman et al 2010, Carter et al 2019). Wider flood inundation carries invasive propagules
farther out in the river floodplain and braided channel complexes (Martinez et al. 2016). In these habitats
knotweed (Polygonum spp.) and reed canarygrass (Phalarus arundinacea) thrive, altering structure and flow,
litter fall, and insect prey production, and arresting growth of trees for large wood and shade. Where these
disturbances erode riverbanks and damage roads, Scotch broom seeds introduced during reconstruction of river
adjacent roads and restoration projects spread to adjacent gravel bars, where the leguminousnitrogen-fixing
species thrives with deep roots reaching hyporheic flow (Carter et al. 2019). Landslides initiating in infested
roads and harvest units transport propagules of Scotch broom and other non-natives (e.g. foxglove (Digitalus
purpurea), tansy ragwort (Jacobaea vulgaris), European blackberry (Rubus bifrons, R. lacinatus) downstream
channels to the main stem river. Reed canarygrass seeds introduced in hay and straw used for erosion control
are transported down ditches into streams, side-channels, and the river. Where invasive species establish and
expand, a continuing feedback loop replacing native species reduces shade, humidity, large wood, leaf litter,
insect prey, and other services provided by mature resilient native floodplain and riparian forests.
Forests
Restoration of native forests, particularly the old-growth patch mosaic that once characterized the Middle Hoh
River valley is essential to sustaining salmon habitat and building climate resiliency. Forest restoration within
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the river valley requires restoring the large wood cycle that depended on the big trees the valley was famous
for. Those big trees formed stable logjams that formed “islands” within and along the margins of the channel
migration zone on which trees could grow old and sustain the supply of big wood (Figures 3b, 3d). Since big
trees are rare, it will take hundreds of years to restore the river’s ecosystem without intervention to emulate the
function of the big trees. Restoration needs to include construction of stable logjams to restore the forest patch
mosaic and side channel network of the river. This has been successfully done in the Upper Quinault River,
Lower Elwha River, Dungeness River, South and North Forks of the Nooksack Rivers, and other rivers.
Restoration actions on these rivers have not only restored channel anabranching and riparian forests, but have
helped protect local communities and infrastructure. It must be accompanied by native conifer planting and
invasive species control. All these actions are needed to restore a resilient river corridor that will sustain
keystone species such as salmon as well as protecting the local community.
Climate change is impacting forests; increasing temperatures, reducing snowpack and changing west side
Olympic Peninsula precipitation patterns resulting in more winter flooding, and lower summer stream flows
(Halofsky et al. 2011). More extreme temperature regimes and low snowpack have resulted in severe drought
years such as in 2015, when the Paradise Fire, a rare extensive coastal temperate rain forest fire, occurred in
the Upper Queets River basin burning more than four square miles of rainforest (2,796 ac) (Current Fire Status -
Olympic National Park (U.S. National Park Service) (nps.gov)). The H-1500 Maple Creek fire burned 70-ac in
August 2021. The potential for wildfires within the temperate rain forests of the Olympic Peninsula are
projected to increase (Perry et al. 2015; Halofsky et al. 2011). Forested slopes at middle elevations are
particularly vulnerable to fires initiated by lightning during dry conditions and have the potential to spread
rapidly upslope. Extensive burns reduce slope roughness and increase surface water runoff that, in turn, may
impact water quality and geomorphic processes in the floodplain below. Fortunately, where they exist mature
riparian forests are naturally resilient to adjacent forest fires due to the locally higher levels of humidity. Mature
forested floodplain side channel networks are essential to provide cooler thermal refugia for salmon as the
climate warms. In addition to climate increased fire frequency, channel migration rates are projected to increase
that threaten to erode and carry invasive plant propagules into the riparian forests.
Removal of much of the Middle Hoh River riparian forest in the 20th century has reduced the area of mature
floodplain forest and associated side channel network–the area of mature side channel aquatic habitat. Mature
riparian forests are the source of large conifer riparian trees–keystones of mature riparian and aquatic
ecosystems. Logging of the mature riparian forest resulted in a dramatic acceleration of channel migration rates
and replacement by red alder dominated riparian forests with few conifers to replace the large trees that were,
prior to logging, common along the banks of the Middle Hoh. Streams affected by logging were significantly
warmer than unaffected streams, and temperatures exceeded the Washington State aquatic life criteria existing
at the time (Hatten, 1992; Hatten & Conrad, 1995; Murray et al., 2000). The proportion of sub-basin classified as
relatively mature (late seral) forest was the best single variable for predicting mean average hourly and daily
maximum water temperatures (Hatten, 1992).
The loss of large keystone coniferous trees has further resulted in loss of large wood jams, in-channel habitat,
and forested islands, all contributing to the decline in salmon populations. More recent conversion to Scotch
broom in reaches downstream of bank revetments and landslides from invaded timberlands has reduced early
successional species necessary to provide organic matter and soil nutrients for mature riparian forest
development (10KYI, Carter et al., Grove et al.).
Wood jam islands are stable refugia for establishment of riparian conifers. Alder-dominated floodplains without
wood jam hard points, together with climate driven increases in channel migration, portrays a future floodplain
forest continuously dominated by red alder or Scotch broom. Without large wood jams very few floodplain
conifers will become established as the channel migrates freely across the valley bottom. Climate increased
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channel migration will in turn require larger trees to create stable wood jams. In effect the current and future
river and riparian forest ecosystem has shifted from an historic state of mid-channel mature forested islands;
anastomosing primary and secondary channel network and patchwork of mature floodplain forests; to a
simplified more braided floodplain state dominated by young red alder and characterized by a lack of stable
large wood. This scenario will result in a future Middle Hoh River–likely on the order of hundreds of years to
recover–in which large wood generated patchwork channel and floodplain forest processes are lost resulting in
continuous degradation and loss of both in-channel salmon habitat and riparian forest fish and wildlife habitat.
Invasive Species Trends
Invasive non-native plants are a threat to forest succession, aquatic habitat formation and climate resiliency on
the Hoh River. After two decades of action to prevent and control knotweeds (Fallopia spp.), Scotch broom
(Cytisus scoparius), reed canarygrass (Phalarus arundinacea), herb Robert (Geranium Robertianum), and Canada
thistle (Circium arvense), significant seedbanks and new introductions by a variety of activities in the watershed
require river-wide persistent and continuous prevention and control activities.
The climatic, hillslope, and riverine disturbance regimes that impact the watershed’s natural and built
infrastructure create conditions ideal for the invasion of non-native invasive plants, which out-compete native
plants – especially the early successional species – willow (Salix L.) and red alder (Alnus rubra). These invasions
delay and impede floodplain forest development, degrade forest function and services, and require significant,
persistent, and continued investment and implementation of active control practices.
Persistent work has been conducted over the past two decades to prevent the spread of non-native invasive
Eurasian plants and habitats can be resilient to these impacts where protected and restored. Successive projects
have been implemented beginning in 2003, resulting in benefits to the local ecosystem through increased
protection from competition for space, nutrients, and water; and a river corridor that continues to provide
foundational ecosystem services of native plant communities.
Invasive plants move between multiple ownerships with differing capacity, interest, legal authority or
responsibility for control in each watershed on the coast. Layered on that ownership, rivers and roads connect
between watersheds, and invasive species move down these pathways. Each entity conducts some weed
control, but all lack sufficient resources, interest, or strategies to address species moving across their ownership
boundaries via wind, water, construction, or traffic. When small Scotch broom, knotweed, reed canarygrass,
everlasting peavine (Lathyrus latifolia), and others are eliminated from roadsides, source populations are
prevented from traveling down ditches and through culverts to streams, where water transports each seed to
bare gravel and banks which are ideal environments for invasion.
Invasive species degrade all habitats and restoration strategies. A common assumption is dense forest shade
will control invasive plants. Our experience shows that none are ever fully eliminated by shade, and a single
plant that contributes its load of seed to wind, water, tires or hooves will start new populations that must be
located and prevented from seed production once again.
“Lag time” as described by Crooks et al., is the process of introduction and explosion of invasive species into
ecosystems, and those where environmental conditions are deteriorating or disrupted are expected to
experience an increased rate of invasion over time. Decades may pass before there exist enough propagules in a
watershed such as the Hoh to cause an explosion. Knotweed was stable in planted locations in the upper Middle
Hoh until a channel avulsion related to a high flow event in or around 1999 and after 20-yrs of treatment,
continues to be found along the entire corridor in single stems and clumps. European blackberry has been
present since homesteading in the late 1800’s, and seeds are spread by frugivorous birds, generalists such as
American Robin (Turdus migratorius) and European starling (Sturnus vulgaris). The observed ‘lag time’ since
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introduction for European blackberry, knotweeds, and Canada thistle in the Hoh watershed is approximately a
century post-homesteading, and for Scotch broom, herb Robert and reed canarygrass, two decades since
introduction through road and river revetment construction, mowing and hay introductions.
Invasive Species Introductions and Persistence in the Hoh Watershed
Funding for invasive species other than knotweed did not become available until 2011, after multiple
introductions, especially during years of Upper Hoh Road bank protection and repair. With multiple species in
multiple sites spreading for a decade unimpeded, googles of propagules (seeds and fragments of root, rhizome,
or stem) capable of producing a new plant) ‘banked’ in the substrates of terraces, floodplains, river bars and
banks, and along roads in the middle Hoh watershed. These propagule banks are continual sources of all
species, and are easily moved in river migration, scour, deposition, or by equipment.
Programmatic invasive plant prevention and control in the watershed
10KYI has worked for two decades to reduce the spread of non-native invasive Eurasian plants so that habitats
can be resilient to these impacts where protected and restored. Work conducted since 2003 has resulted in
benefits to the local ecosystem through increased protection from competition for space, nutrients, and water;
and has resulted in a river corridor that continues to provide the ecosystem services of native plant
communities.
Invasive plants move between multiple ownerships with differing capacity, interest, legal authority or
responsibility for control in each watershed on the coast. Layered on that ownership, rivers and roads connect
between watersheds, and invasive species move down these pathways. Each entity conducts some weed
control, but all lack sufficient resources, interest, or strategies to address species moving across their ownership
boundaries via wind, water, construction, or traffic. When small Scotch broom, knotweed, reed canarygrass,
everlasting peavine (Lathyrus latifolia), spotted jewelweed (Impatiens capensis) and others are eliminated from
roadsides, source populations are prevented from traveling down ditches and through culverts to streams,
where water transports each seed to bare gravel and banks that offer ideal environments for invasion.
Invasive species degrade all habitats and restoration strategies. A common assumption is dense forest shade
will control invasive plants. 10KYI’s experience demonstrates that none are ever fully eliminated by shade, and
that shade is temporary on the dynamic Hoh River. A single plant that contributes its load of seed to wind,
water, tires or hooves will start new populations that must be located and prevented from seed production once
again.
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Table 11. Objectives and strategies necessary to achieve the resiliency goal of restoring native vegetation.
RESTORATION GOAL OBJECTIVES STRATEGIES
Healthy, resilient native forests able to recover
from disturbances
Eliminate
invasive
non-native plants in the MHRC and
the Hoh
watershed (and Olympic Coast)
Roads
• End invasive species introductions via roads and roadwork:
o Integrate prevention and control actions into all road and
roadwork projects – federal, tribal, state, county, local,
and private
o Develop new prevention and control guidance, policies,
tools, and methods
Certified weed-free gravel and materials
Equipment wash stations
River Corridor
• End invasive species introductions via restoration,
construction, and development projects:
o Integrate prevention and control actions into all projects
– federal, tribal, state, county, local, and private
o Contribute services via 10KYI’s Pulling Together in
Restoration Project (PTIR), Coastal Conservation Corps
(CCC), and other programs
o Develop new prevention and control guidance, policies,
tools, and methods
Applied Science
• Develop and implement studies to inform adaptation and restoration strategies: o Scotch Broom Ecological Impact Study (10KYI with UCSC
and NAU, PNW)
o Reed Canarygrass Ecological Impact Study (10KYI with ONP, WDFW, PNW)
o Scotch Broom Pyrolysis Pilot (10KYI)
o Glacial Retreat Study (TBD – 10KYI and partners)
o Herb Robert Allelopathy Study (TBD – 10KYI) o Biogeomorphologic Influence of Invasive Species (TBD –
10KYI)
Use genetically appropriate,
locally-sourced
native species for revegetation
• Develop a Native Plant Salvage (NPS) Program
• Establish a facility for the NPS Program
• Develop a nursery for native plants for Hoh watershed riparian, floodplain, and roadside revegetation
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Table 12. The Invasive plant species propagation, seed number, seed viability, and allelopathy (with sources)
INVASIVE PLANT
SPECIES PROPAGATES
VIA
ANNUAL NUMBER OF SEEDS
PER PLANT SEED VIABILITY ALLEOPATHIC
Scotch broom Seeds Average: 9,650 seeds1
Maximum: 18,000 seeds2
Average: 5 – 20-yrs1
Maximum: 60-80-yrs2,1
Yes9
Knotweed
Seeds*
Rhizomes
Nodes
Average: 50,000 seeds per stem8 Maximum: 150,000 seeds per stem8 Average: 1 – 2-yrs8 Maximum: 15-yrs7
Yes10
Reed canarygrass
Seeds
Rhizomes
Nodes
Average: Varies between populations14 Maximum: 600 seeds3 Average: 1 – 6-yrs14 Maximum: 30-yrs14
Suspected11;
more research
is needed
Herb Robert Seeds Average: 500 - 1,000 seeds4
Maximum: 1,550 seeds16
Average: 3 – 5-yrs15
Maximum: 6-yrs16
Yes4
Canada thistle Seeds Rhizomes Average: 1,000 - 1,500 seeds5,6 Maximum 5,300 seeds6 Average: 3-5-yrs17 Maximum: 20-yrs5
Suspected12;
more research
is needed
*Bohemian knotweed1-81
Invasive Plant Control in the MHRP by River Reaches
The 10KYI Hoh River Invasives Species Prevention & Control Program (ISPCP) divides the river into floodplain
complexes and reaches associated with tributaries. Over the past two decades of invasives control on the Hoh
River, data has been collected based on reaches and floodplains named for tributaries or other features as
follows:
Table 13. Middle Hoh River Resiliency Plan reaches relative to ISPC reaches
MIDDLE HOH RIVER
RESILIENCY PLAN
REACHES
HOH RIVER ISPC PROJECT REACHES
Oxbow Canyon Oxbow Canyon, Hell Roaring Creek
Willoughby Creek Alder Creek, Winfield Creek, Elk Creek and Elk Creek Floodplain, Schmidt Bar, Peterson’s
Floodplain, Lindner Bar (mid to lower)
1 Washington Noxious Weed Control Board: Cytisus scoparius: https://www.nwcb.wa.gov/images/weeds/Cytisus-scoparius-
WF.pdf
2 Jefferson County Noxious Weed Control Board Fact Sheet: Scotch broom (Cytisus scoparius):
https://www.nwcb.wa.gov/images/weeds/ScotchBroom_Jefferson.pdf
3 Jefferson County Noxious Weed Control Board Best Management Practices: Reed canarygrass (Phalaris arundinacea):
https://jeffersoncountypublichealth.org/DocumentCenter/View/2959/Reed-Canarygrass
4 Jefferson County Noxious Weed Control Board Best Management Practices: Herb Robert (Geranium robertianum):
https://www.co.jefferson.wa.us/DocumentCenter/View/2954/Herb-Robert
5 Jefferson County Noxious Weed Control Board Best Management Practices: Canada thistle (Cirsium arvense):
https://www.co.jefferson.wa.us/DocumentCenter/View/2950/Canada-Thistle
6 Washington Noxious Weed Control Board: Canada thistle (Cirsium arvense): https://www.nwcb.wa.gov/weeds/canada-
thistle
7 Jefferson County Noxious Weed Control Board Best Management Practices: Invasive Knotweeds (Bohemian Knotweed,
Japanese Knotweed, Giant Knotweed, Himalayan Knotweed):
https://www.jeffersoncountypublichealth.org/DocumentCenter/View/2955/Knotweed
8 US Forest Service Fire Effects Information System: Polygonum sachalinense, P. cuspidatum, P. × bohemicum:
https://www.fs.fed.us/database/feis/plants/forb/polspp/all.html#87
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MIDDLE HOH RIVER
RESILIENCY PLAN
REACHES
HOH RIVER ISPC PROJECT REACHES
Morgan’s Crossing Upper Lindner Bar, High Bluffs, Rock Creek, Clear Creek, Tower Creek
Spruce Canyon Canyon, Maple Creek, Pole Creek, Dismal Creek
Huelsdonk - South Fork Owl Creek, Spruce Creek, Spruce Flats, Canyon Creek, Fletcher Island, Lewis Channel, Fletcher
Ranch, Brandeberry Lots, Richmond Island, Upper Brandeberry Island, Crippen Homestead
Invasive Plants in the Hoh Watershed – Risks and Hazards by Site and Activity:
Table 14. The risk and hazards of invasive plant spread via streamflow, roads, equipment, hillslope
processes, and weather
*Level of risk and hazard: High (H), Moderate (M), Low (L), Not applicable (N/A) **Propagules: Rhizome (), Fragment-Stem (F/S), Fragment-Root (F/R), Seed (S)
Invasive Plants in the Hoh Watershed – Species, Sources, Impacts
Species in the watershed
Knotweeds, Scotch broom, reed canarygrass, herb Robert, Canada thistle, tansy ragwort (Jacobaea vulgaris),
non-native blackberry Himalayan or Armenian (Rubus bifrons) and Evergreen or cut-leaf (Rubus lacinatus),
spotted jewelweed (Impatiens capensis) and seven additional invasive species and noxious weeds are widely
distributed at different densities throughout the Hoh watershed. Typically, a new species is introduced each
year, and discovered during continuous road, river, and site surveys.
Points and polygons collected during field surveys document plant species, phenology, site type, treatment and
more, collated into maps and databases since 2003. To support resiliency planning and restoration project
implementation in the Middle Hoh, layers of invasive species that impact growth of native forest have been
overlain onto the MHRP Riparian and Floodplain Forest maps (Appendix D, Map 5 and Map 8), with examples
from Morgan’s Crossing reach provided in in true color aerial imagery Figure 29 and Figure 30):
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Figure 29. Scotch Broom infestation in the Morgan’s West Reach.
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Figure 30. Scotch Broom and forest type cover of the Morgan’s West Reach.
Sources
Knotweed, Canada thistle and the blackberry species have been present since homesteading in the late 1800’s
and early 1900’s. Knotweed was originally planted at homesteads both as an ornamental and to provide forage
for European honeybees late into the fall. Canada thistle and tansy ragwort were likely accidental introductions
in livestock feed in earlier landings of Europeans to the coast (NRCS). The European blackberry species –
Himalayan (Rubus bifrons), and Evergreen (R. lacinatus) were planted for their large and prolific berries. Some
reports suggest that reed canarygrass was introduced at homesteads to provide shade-tolerant and fast-growing
forage for livestock among the huge stumps from cleared old-growth forest (NRCS). Reed canarygrass was first
observed in the river corridor in 2009 (Appendix D, Map 8, Figure 32) and is believed to have been more recently
introduced in hay or straw used for livestock or roadside erosion control, or field and roadside mowing
equipment used in other watersheds and then in Hoh valley hayfields2. Herb Robert was first observed in the
mid-90’s in Olympic National Park at the Snider Creek equipment yard – likely unintentionally brought from the
2 Some reports suggest that reed canarygrass was introduced at homesteads to provide shade-tolerant fast-growing forage for livestock
among the huge stumps from cleared old-growth forest, but it was not found until 2009 in the river corridor (NRCS 2010).
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north and east Peninsula where it has been established. Until treatment is expanded upriver, this species will
continue to move into MHRP reaches.
Recent introductions in road and bank protection work in the middle and upper river are everlasting peavine
(Lathyrus latifolius), spotted jewelweed (Impatiens capenisis), wild chervil (Anthriscus sylvestris), St. John’s-wort
(Hypericum perforatum) and Queen Anne’s lace (Daucus carota). Each of these species are quickly caught and
treated, but boots, vehicles, mowing and construction equipment continuously introduce propagules that must
be controlled before seeds are produced and can be spread.
Table 15. The condensed acres of invasive plants inventoried and treated in 2020 within the Middle Hoh
Resiliency Plan (MHRP) reaches require surveys of 3,000 acres of forested floodplain, channels, and river bars.
MHRP REACHES KNOTWEED SCOTCH
BROOM
REED
CANARYGRASS HERB ROBERT CANADA
THISTLE
Oxbow Canyon 0.0004 ac 0.0004 ac 0.00 ac 0.00 ac 0.00 ac
Willoughby Creek 0.01 ac 8.62 ac 0.11 ac 0.007 ac 0.09 ac
Morgan’s 0.004 ac 4.19 ac 1.54 ac 0.90 ac 0.17 ac
Spruce Canyon 0.00 ac 0.00 ac 0.0002 ac 0.02 ac 0.01 ac
Huelsdonk/South Fork Hoh 0.01 ac 2.28 ac 3.83 ac 1.35 ac 0.22 ac
Upper Hoh Road 0.00 ac 0.01 ac 0.02 ac 0.06 ac 0.00 ac
Total 0.03 ac 15.1 ac 5.51 ac 2.33 ac 0.49 ac
Impacts by these species to the development and resiliency of native forest communities in the Hoh
watershed
Invasive plants impede and interfere with the germination, growth, and health of native plant species. Through a
variety of adaptations, each of the listed non-native Eurasian species establish and spread in the varying degrees
of moisture, flooding, and low nutrient disturbance zones in gravel bars. Each species form monocultures that
arrest the growth of native species, and reduce the space, soil nutrients, water availability, and light, replacing
the functions and services provided by native plants including food, structure, and shade.
Four species are particularly detrimental in the Hoh watershed’s managed forests and river floodplains to a
range of native plants, fish, and wildlife:
Scotch broom (Cytisus scoparius) – Arrests the growth of early successional riparian plants which set the
ecological stage for conifer forests. Outcompetes and replaces native shrubs used by pollinators, doesn’t feed
native insects, reducing forage for frugivorous and insectivorous small mammals and birds. Alters soil chemistry
with nitrogen fixation and additional requirement for phosphorus. Toxic to grazers – elk, deer, livestock.
Reduction in organic contribution for soil development (loss of leaf litter from red alder). Flammable volatile oils
are reported to cause allelopathy in soils.
A SB monoculture grows to 10-ft tall, producing 10,000 seeds per plant per year, which may remain viable for
80-years. SB is shown to arrests native forest succession through a variety of influences, replacing early
successional native willow, alder, and in time, the conifer forests providing forage, shade, nutrients, and other
services including large woody debris, bank stability and sediment filtration to keep streams and rivers and
forests naturally healthy (Grove et al. 2017, Slesak et al. 2016). SB alters the composition of several important
soil nutrients and disrupts the mycorrhizal fungi critical to healthy forest growth (Grove). It is mildly toxic to
herbivores, which avoid it. It is also more flammable than native shrubs and trees. Scotch broom survives both
floods and drought, influencing sediment transport and storage, and morphology of bars and terraces. Scotch
broom possesses several traits that make it tolerant and avoidant of drought conditions: High root length
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density, low leaf area to root mass ratio, low specific leaf area, photosynthetic stems, and a drought-deciduous
phenology (Carter et.al. 2019, Bannister 1986; Bossard and Rejmanek 1994; Matı´as et al. 2012; Boldrin et al.
2017). The bushy branches and long roots anchor the plants in mobile river bars, reaching hyporheic below the
bar surface, while collecting fine sediment in high water events.
A report of the Hoh Tribe paddling canoes across the river to the Huelsdonk homestead on the north side in the
1940’s to put out a fire in Scotch broom is an indication that species was present, but it was not widely observed
in the river itself until after large scale road revetment work began in 1996 through 2007 on the Upper Hoh
Road, and 1999 and ongoing on Oil City Road, and 2004 on SR 101. All these construction sites introduced Scotch
broom to the river, which was established by 2007 and continues to produce googols of seed despite continuous
control effort.
Figure 31. Summary of Scotch Broom acreage for reaches of the Middle Hoh valley.
Reed canarygrass (Phalarus arundinacea) Impedes access to off-channel habitats and fills floodplain side-
channels, wetlands and channel margins. Slows and warms water, reducing dissolved oxygen and cold water
refugia. Reduces production of native insect and amphibian prey species utilized by juvenile salmon (Weilhofer
et al. 2016, WDFW).
Condensed acres
of Scotch broom
inventoried and
treated between
2017-2020 within
the Middle Hoh
Resiliency Plan
(MHRP) reaches
10,000 Years Ins�tute
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Figure 32. Summary of Reed Canary grass for reaches of the Middle Hoh Valley.
Knotweeds (Polygonum spp.) Limits growth of early and later successional native riparian plant species
through alteration of soil nutrients, dense shade during the growing season (Urgenson, 2009, Claeson et al.
2013)), and loss of woody structures to slow winter flow and protect banks from erosion. Causes loss of litterfall
benefitting macroinvertebrates, and thus stream biota, and loss of forage for grazing mammals. However,
European honeybees and native bald-faced hornets are heavy users of late fall blossoms.
Knotweed rhizomes are documented to extend 5 meters into substrates and 10 meters laterally from each
clump or stem. A 2cm fragment of rhizome can produce a new plant. Each node on the cane (stem) will root
and sprout in contact with water or damp soil. Rhizomes 4 meters long and 1 meter wide have been observed
on the Hoh River, exposed by river scour. Treating small leaves growing from these huge rhizomes does not
translocate enough herbicide to effectively control them, and the river often breaks these apart, floating out and
depositing in new locations. Plants may emerge as late as October from deeply buried fragments, which is too
late to treat effectively in wet conditions and higher water. Thus, nearly two decades after treatment began,
knotweed persists in the watershed at very low levels – 2020 surveys found scattered plants and clumps totaling
0.12-ac in area over 3400-ac of floodplain, river bars and banks searched between RM 30 and RM 0.5. Three
sites where knotweed had not been found in 2 to 7 years are Brandeberry Island, Elk Creek side-channel, and
Clear Creek side-channel, and all had knotweed emerge again in 2021 (Appendix D, Map 8).
Condensed acres
of reed
canarygrass
inventoried and
treated between
2017-2020 within
the Middle Hoh
Resiliency Plan
(MHRP) reaches
10,000 Years Ins�tute
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Figure 33. Summary of Knotweed for reaches of the Middle Hoh Valley.
Herb Robert Weakly perennial – primarily annual. Limits growth of native forest understory plants through
strong allelopathy (Mardani et.al. 2016), reducing browse for herbivores and nectar for native pollinators.
Research is needed to evaluate effect on native woody species. Sticky seeds remain dormant for 5 years (Jones
and Reichard 2009). Seeds are transported by water, animals, and boots. Seedlings germinate as mature plants
are removed. The species begins flowering in February, forms seeds by April, and continues growth and seed
production through November.
Figure 34. Summary of Herb Robert for reaches of the Middle Hoh Valley.
Condensed acres
of knotweed
inventoried and
treated between
2017-2020 within
the Middle Hoh
Resiliency Plan
(MHRP) reaches
10,000 Years Ins�tute
Condensed acres
of herb Robert
inventoried and
treated between
2017-2020 within
the Middle Hoh
Resiliency Plan
(MHRP) reaches
10,000 Years Ins�tute
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These non-native species each tolerate a range of conditions in shade or sun, moist or dry, growing at varying
rates and to different heights depending on site characteristics. Similarly, in different site conditions, each can
reach maturity at different times during each year, necessitating repeat surveys and treatments each year,
depending on river flow, season, seed bank, and weather.
Figure 35. Summary of invasive plant treatment timing throughout the year.
Desired Future Conditions
A key element to the development of this resiliency plan is to identify desired future conditions, to provide a
target through which we can develop a series of steps to achieve. Incorporating our understanding of the reach
with projected and anticipated changes provides an opportunity to improve resiliency in the Middle Hoh. Of
particular interest are how restoration of riverine processes, improvements to roads or changes in landuse and
public access could improve resiliency for the community and environment. Short-, intermediate- and long-term
desired future conditions statements for each of these categories are provided that include overarching goals
and specific objectives to meet these conditions.
Resiliency Corridor
The core of our approach to the development of resiliency planning for the reaches of the Middle Hoh is the
delineation of a resiliency corridor, which estimates the minimum spatial footprint required to sustain habitat-
forming processes along the river corridor. The processes that form and sustain aquatic habitat in a western
Washington river system – lateral channel migration, channel avulsion (i.e., rapid channel relocation), flow
splitting, overbank inundation – are dynamic and require both sufficient space and a healthy riparian forest to
function (Collins et al. 2012).
NSD utilized an examination of the geomorphic, hydraulic, and aquatic habitat parameters to define the
Resiliency Corridor for the study reach. The resiliency corridor was defined as the entire valley bottom
throughout the project reach based on following:
Invasive plant
survey and
treatment �ming
based on species
life history,
treatment
methods, site and
weather
condi�ons
10,000 Years Ins�tute
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1. The 100-yr floodplain which includes areas frequently subject to flood inundation,
2. The channel migration zone,
3. Floodplain topography and geomorphology, including areas with clear evidence of historical alluvial
channels (GMZ),
4. The meander bend amplitude and frequency.
The boundary of the resiliency corridor should be viewed as a planning tool to guide decision making for actions
occurring within the corridor. Actions taken within the corridor should consider their impact on natural process
functions contributing to available high-quality habitat. Areas within the corridor that are undeveloped should
remain so, be evaluated for invasive plant species presence and need for restoration. Where natural processes
are actively creating and supporting aquatic habitat and/or climax riparian communities exist the area should be
targeted for preservation and invasive species monitoring. Where development exists within the corridor there
is an opportunity to improve resiliency for the Hoh River, and if possible, restoration should be the preferred
alternative. If restoration is not achievable, alternatives that minimize impacts and/or mitigate for impairments
to natural processes should be pursued to the extent possible.
Acquisition and land conservation provide for the greatest opportunity to develop long-term resiliency, that is
naturally sustained and provides for people and many other dependent species. The Middle Hoh is unique in
that there are currently 194-ac of land in conservation and 374-ac of federal or state ownership within the
resiliency corridor that would inhibit future development. This represents 74% of the corridor, a wonderful
foundation to continue to build upon with future acquisitions and conservation easements. When private
property comes up for sale in these areas it should be purchased. Acquisition will eliminate future flood
damages and enable habitat restoration. Landowners that are receptive can consider conservation easements as
a means of preserving natural areas while retaining ownership. Funding programs also exist to help
homeowners relocate outside flood prone areas. This will also reduce flood damage liabilities to individuals and
the public and consistent with current guidance by the Association of State Floodplain Managers (ASFPM) and
the Federal Emergency Management Agency (FEMA).
Long-Term Desired Conditions (include overarching goals and specific
objectives)
Looking beyond 20-yrs the goal is to have completed all of items in the action plan, and focus the effort on
continued passive restoration, monitoring and maintaining community engagement to ensure this vision for the
Middle Hoh can persist well into the future. The river will appear different that it does today, with more channel
threads and instream islands resulting in narrower and deeper channels on average. Most of the energy of the
river is partitioned interacting with stable instream wood, instead of being released eroding channel banks,
resulting in diminished channel migration rates that have allowed the floodplain riparian forest to mature. It will
take more than a century for these forests to produce trees of sufficient size to form stable logjams in the river
once recruited, however conifer release and planting are accelerating natural succession of the riparian forest.
The ELJs constructed in the river and floodplains mimic the role of these large trees once played in the channel,
allowing the system to recover and begin producing new trees to replace the ELJs once they deteriorate. The
expected lifespan of the ELJs suggests that additional phases of ELJs construction will be needed to ensure the
system remains stable long enough for the riparian forests to mature sufficiently to become self-maintaining.
The findings of the Upper Hoh Road Plan successfully identified an alternative route for the road that meets the
needs of the community, is outside of the resiliency corridor, CMZ, and is on low-landslide risk terrain (or the
risk has been otherwise mitigated). This new route maintains access to the river, providing landowner and
recreational access, while problematic chronic washout and side-prone sections of the road have been
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decommissioned and removed. Traffic heading to and from ONP on the new route has diminished overall traffic
close to the river and homes, with individuals looking to access the river locally are directed on spur roads to
established sites and local businesses.
Recreation opportunities in the Middle Hoh River have been expanded to include a trail network connecting
Highway 101 and the Hoh Visitor Center, new interpretive trails along the river educating the public about the
ecosystem, bike lanes along the new Upper Hoh Road to reduce traffic and noise and improved stabilized boat
launch sites that persist following high water. Working with entities that manage, own property or enter into
conservation easements for ecosystem preservation to consider maintaining existing public access to the river
so individuals can return to their favorite places.
Establish, sustain and protect the Middle Hoh River Resiliency Corridor and all elements of the Action Plan.
Restore the large wood cycle to the valley and its old-growth forests. Ensure residents and visitors have safe
access and their exposure to flood and erosion damages are minimal. Restoration of native salmon populations
and native plant species. Continue updates to resiliency planning and community communications.
Intermediate-Term Desired Conditions
For the purposes of this discussion, intermediate-term refers to the next 5 - 20-yrs and is a time when active
restoration efforts are underway and wrapping up, having set the stage for a self-sustaining ecosystem where
passive actions can be used to accommodate unanticipated shifts due to climate change. Active restoration
actions include continued focus on restoration of off-channel rearing habitat and partitioning flow to reduce
stream energy. Restoration projects have been implemented at the sites ranked as having the highest priority
for restoration, and progress is continuing down the priority list toward the bottom. Monitoring is showing more
juveniles out-migrating to the sea, indicating restoration actions are having a measured effect that will only
continue to improve. Returning adults encounter more deep pools as they migrate upstream from instream ELJs
forcing scour, creating resting spots as they move upstream. All these changes are making it easier for the
salmon that use the Middle Hoh to adapt to other changes brought about by the changing climate. Known
patches of invasive species have been eradicated and continued monitoring has limited spreading within the
Middle Hoh.
Work is beginning after years of planning on a new road that will reduce the impact on the environment and is
safer for all users and the local community. Most traffic has been routed further from local homes and the river,
while maintaining access. Refinements to the alignments continue as new information is gathered and/or
conditions change. The chronic road washout locations on the Upper Hoh Road have been stabilized and
continue to provide protection from erosion as the new alignment is constructed.
A series of trails connecting Highway 101 to the Hoh Visitor Center are under construction providing alternative
access to ONP, or an alternative to visiting ONP during high-demand times. Additional interpretive trails along
the river are being built that highlight the restoration work underway and the vision for the future.
Short-Term Desired Conditions
For the purposes of this discussion, short-term refers to the next 5-yrs. Actions that can be achieved in the
short-term include those such as riparian conifer inter-planting, invasive species monitoring and treatment,
thinning, stabilize known chronic road washout locations, opportunistic acquisition of property within the
resiliency corridor, maintaining the leadership group that will work to realize the goals of this plan. Floodplain
protection from channel migration, establishing islands in the channel that are protected from erosion.
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Over the next 5-yrs we envision the establishment of a Middle Hoh working group consisting of a range of
stakeholders who work to move the plan forward. A riparian forest management plan for the Middle Hoh was
developed that has guided the initiation of silviculture actions aimed at acceleration the conversion to a mature
forest, including conifer interplanting, thinning, understory management, invasive species monitoring and
control, as well as formation of volunteer groups. Instream restoration projects have been implemented where
high-quality floodplain habitat was at most risk of loss through erosion, utilizing ELJs strategically placed in the
channel, banks and floodplain to mimic the role large wood once played in the Middle Hoh. These ELJs are used
to limit avulsion potential through side and relic channels, reduce channel migration rates through young
floodplain forests and split the main stem channel, forming instream islands that can persist over time. As these
projects begin to be implemented new islands are forming in the river and vegetation is starting to colonize.
Conifers are emerging from the dense alder stands where thinning and planting was completed, and understory
invasive species have been eliminated and/or are receiving continual prevention and control efforts.
In response to a broader national strategy to reduce the resource burden on the National Park Service, a
reservation system was established for ONP visitors to the Hoh Rain Forest. This change in policy has increased
demand for recreation and engagement with nature in the region, and decreased traffic along the Upper Hoh
Road as a result. While overall traffic is down, more recreational users are looking to the Middle Hoh
Chronic washout locations along the Upper Hoh Road have been stabilized using wood-based structures, and a
plan has been developed to consider realignment where the road is within the Resiliency Corridor and/or CMZ.
Improvements to the stability of existing boat launches have been improved or have been moved to limit
susceptibility to erosion during high flows. Boat launches that have been lost to erosion over time are under
evaluation to determine need and appropriate locations.
Resiliency Plan actions will likely take several decades even if they are aggressively funded. The actions will likely
be needed into perpetuity. The greater the geographic extent and rate that actions are implemented, the faster
the goals of the Resiliency Plan will be achieved. The magnitude of actions needed would eventually dimension.
But if the Actions are not implemented, the severity of impacts will continue to grow and become more
expensive to treat. Summary of Resiliency Plan actions, all of which can be implemented concurrently, are listed
below (presented earlier in document):
1. Conifer floodplain planting within the Resiliency Corridor
2. Invasive plant control throughout the valley
3. Construction of stable engineered logjams (ELJs) within and along the margins of active channel
migration
4. Relocation of Upper Hoh Road outside the CMZ
5. Construction of large roughness elements (ELJs) and riparian buffers along road where it can’t be moved
6. Acquisition or conservation easements of land within the Resiliency Corridor.
7. Relocate residents at high risk of erosion and flooding to safe areas outside the Resiliency Corridor
8. Focus new development in upland areas outside the Resiliency Corridor
A foundational framework of the Resiliency Plan is taken from the successful work that has been done on the
Upper Quinault River (QIN 2006). Like the Hoh (Figure 3f), the Upper Quinault Valley historically had extensive
old-growth forest areas with networks of stable side channels (Figure 36). Historic clearing led to more active
channel migration which has eroded these areas and prevent similar habitats from re-forming (QIN 2006). This
consists of linking stable roughness elements (ELJs) to restoring forests and side channels. The basic concept is
illustrated in Figure 37. The geographic framework is to protect margins of resiliency corridor so that side
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channels can form and be sustained. To do this the density of ELJs increases toward the corridor margins with
lower density further inside the corridor. The Upper Quinault Restoration program led by the Quinault Indian
Nation has been implemented in phases almost every year since 2008. At the PA5 site (Figure 38) several phases
of ELJ construction have been successful in shifting the mainstem river away from development and are
restoring side channels and floodplain forest. ELJs built in the Cispus River in 2021 were subjected to a 100-yr
recurrence flood weeks after construction and they all survived and achieved goals to create restore
anabranching and inundate side channels in existing floodplain forest (Figure 39, Figure 40 and Figure 41).
Figure 36. Illustration of portion of Upper Quinault River Valley (RM 44.3-45.8). The channel traces show the
HMZ and active channel migration zone. The area to the south shows a network of stable side channels flowing through mature forest. Southward migration of the river has eroded important side channel habitat
crucial to salmon and the lack of big timber is preventing the habitat from being reformed. Most recent
historical channel is 2002. Since then the river has migrated further to the south. Adapted from QIN (2006).
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Figure 37. Conceptual geographic framework for restoring large wood cycle, floodplain forests and side
channels. The layout shows protective measures (green squares, zone 1) of property and infrastructure within CMZ, this protection would not be needed in undeveloped areas. The thin blue lines within zone 2-3 represent
stable side channels in an area that natural would be dominated by old-growth (see Figure 3f). The area of
more active channel migration (zone 4) the density of ELJs diminishes. Taken from QIN 2006.
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Figure 38. Implementation of several phases of restoration in the Upper Quinault River. At the site the river
had moved several thousand feet to the south, ultimately destroying one home and threatening the South
Shore Road. The black symbols show constructed ELJs constructed between 2013 and 2017. The ELJs allow
water flow in-between them but discourage the main channel from occupying the area (analogous to zone 2-3
in Figure 37). The project has resulted in the main channel moving north while creating new side channel habitat within the treatment area. The ELJs have also increased the number of new pools with complex cover
and created new floodplain for reforestation.
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Figure 39. Example of large-scale restoration project to restore large wood cycle and side channel habitat in
the Cispus River (Lewis County, WA). Photos show before and after.
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Figure 40. Same reach of the Cispus River, looking downstream on November 24, 2021, after a 100-yr
recurrence peak flow. All 24 of the ELJs are intact and undamaged. The project increased cumulative channel
length over 4-fold and increased the number of pools over 10-fold. Photo by Eli Asher, Cowlitz Tribe.
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Figure 41. Example of engineered logjams constructed in 2020 and 2021 in the Cispus River. The structures
were subjected to a 100-yr flood event in November 2021, only weeks after construction. All 21 of the
structures were undamaged and most collected large volumes of wood. Flow is from right to left. Photo 11-
24-21 by Eli Asher, Cowlitz Tribe.
LOCAL CAPACITY TO SUPPLY RESTORATION NEEDS
Introduction
The goal of this chapter is to provide a summary of the local capacity currently available to support restoration
needs in the region and to give insight to the feasibility of reaching the objectives in the Middle Hoh Resiliency
Plan (MHRP). This chapter also serves to provide an understanding of where there may be gaps in local capacity
impeding restoration progress. Identifying gaps in capacity during Phase 1 of this project will inform local
stakeholders, practitioners, decision makers, and funders where investment is likely needed to help build local
capacity to fulfill restoration objectives of the MHRP.
The information provided in this chapter is a snapshot of the current status of local capacity, and current
strengths and limitations in capacity are anticipated to change with time. Looking ahead, it is important to note
that relatively recent increases in restoration funding to the region are providing ample opportunities build
restoration capacity (e.g., restoration-related education programs, jobs, businesses, etc.).
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For the purposes of this chapter, we are discussing the local capacity to complete Ecological Restoration of
natural processes in the river and floodplain environments. According to the Society for Ecological Restoration,
an international non-profit organization that advances the science, practice and policy of ecological restoration
to sustain biodiversity, improve resilience in a changing climate, and re-establish an ecologically healthy
relationship between nature and culture, Ecological Restoration is defined as the process of assisting the
recovery of an ecosystem that has been degraded, damaged, or destroyed (www.ser-rrc.org).
By definition ecological restoration encompasses a very wide range of projects. The practice of ecological
restoration requires a high degree of ecological knowledge that can be drawn from practitioner experience,
Traditional Ecological Knowledge (TEK), Local Ecological Knowledge (LEK), and scientific discovery. Practitioner
knowledge is derived from experience in repairing ecosystems, and from information from a spectrum of
disciplines (e.g., restoration ecology, agronomy and seed production, forestry, horticulture, botany, wildlife
science, zoology, hydrology, soil science, engineering, landscape design, conservation biology, natural resource
management, etc.). Additionally, LEK and TEK experts, who are typically members of a local community, can
provide extensive and detailed information about sites and ecosystems drawn from their long-term
relationships and connections to these sites. When integrated into restoration projects, these multiple forms of
knowledge provide opportunities to improve restoration outcomes for ecological, social, and cultural benefits.
(Gann, et al, 2019). In the following chapter sections, the term restoration is used when referring to ecological
restoration as defined above.
In the context of this chapter, we are referring to restoration projects that aim to restore river and floodplain
environments, and this scope includes a wide diversity of project types and capacity needs. Restoration project
types considered in this discussion include riparian and floodplain restoration as well as instream restoration.
Generally speaking, floodplain restoration improves floodplain structure, function, connection, and natural
processes. Floodplain restoration actions include on the ground projects as well as efforts to promote land
conservation (e.g., conservation easements, land transactions, etc.). Ground-based projects may strive to
reconnect side channels and off channel habitats via culvert upgrade or removal, channel excavation, and
engineered log jams. Ground-based projects can also include more passive actions that promote healthy forest
plant communities through planting native plants, managing invasive plant species, and forest thinning.
Additionally, floodplain restoration projects could include efforts to address land development and/or land use
in the floodplain. For example, roads, levees, and water diversion infrastructure can have significant negative
impacts to natural floodplain processes. Floodplain restoration projects could include actions such as removing
or upgrading levees; removing or upgrading roads; removing or upgrading water diversion structures, culverts,
etc.
Instream restoration actions include projects that promote natural morphological processes that in turn support
salmon habitat forming processes. Instream restoration projects often overlap with floodplain restoration, as
the stream channel and floodplain are a single, usually complex, system. Instream restoration actions could
include more passive work, using hand tools, or more aggressive actions using large machinery, or even
helicopters. Examples of passive instream restoration projects include: installation of PALs (Post Assisted Log
structures), BDAs (Beaver Dam Analogs), direct felling of trees into the stream, LTPBR (Low Tech Process Based
Restoration) applications, etc. Larger scale instream restoration could include the use of excavation, fill, and the
import of native materials lost due to degradation, such as large wood and log jams. Instream restoration
projects also include projects aimed to reconnect fragmented habitats caused by anthropogenic migration
barriers to fish. For the most part, addressing these migration barriers entails an upgrade to road infrastructure
where a road crosses a fish-bearing stream. These ‘fish passage projects’, when implemented, usually involve
the replacement of the existing infrastructure causing the fish barrier (e.g., culvert conveying streamflow under
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road) with an appropriate structure (e.g., countersunk culvert, bottomless arch, or bridge) that allows
unimpeded fish passage and natural stream processes, such as sediment and wood transport.
All of these restoration projects require more than the physical actions to implement the plan and/or design.
The capacity needed to complete restoration projects also require cultural resources review, permitting work,
engineering, project management, etc. This chapter and the MHRP acknowledges the essential role of cultural
resource protection and the needed capacity to ensure cultural resource compliance.
Recent Restoration – a Snapshot of Restoration Types and Funding Over
Past Five Years
The timeline to develop and implement these various kinds of restoration projects vary widely. The lifespan of
restoration projects can be relatively long and complex, relying on multiple disciplines and expertise, but they
can also be relatively short and straight forward, applying only one or two disciplines to meet individual project
goals and objectives. In researching for this chapter to gain an understanding of the current local capacity to
supply restoration needs, we queried five years of completed and currently active restoration projects in the
region. Project data was collected for all riparian, floodplain, and instream restoration projects in the local
Watershed Resource Inventory Area (WRIA) 20 and the neighboring WRIAs 19 and 21. See Attachment C for the
project list, project type, and associated costs. All of these projects were funded through the WA Salmon
Recovery Funding Board, WA Coast Restoration and Resiliency Initiative Program, Family Forest Fish Passage
Program, or the Brian Abbott Fish Barrier Removal Board. All of these restoration funding programs are
managed by the Washington Recreation and Conservation Office (RCO), and RCO staff supplied the data in early
2021.
Understandably, this list of restoration projects and associated costs do not include all of the funding and
capacity applied to complete each project. Capacity considered, but not quantified here, includes: funding, staff
time, and capacity from local sources (e.g., Counties, Cities, Conservation Districts, etc.), federal sources (e.g.,
EPA, NRCS, Title II, etc.), tribal sources (e.g., BIA, NWIFC, etc.), foundations, and private donors. This inventory of
recent restoration projects does not include protection and acquisition projects (e.g., WA RCO ALEA projects,
Hoh River Trust, The Nature Conservancy, etc.), however these types of land acquisition and protection projects
should still be considered a critical tool in the restoration toolbox.
Elements of Restoration Projects and Associated Capacity Needs
To understand the capacity needed to carry a restoration project from concept to implementation, we must first
understand the steps or phases a typical restoration project goes through to be successful. Gaps in capacity at
any point in project phases can lead to project delays, funding shortfalls, incomplete projects, or poorly
implemented projects. Therefore, it is critical to assure the needed capacity is available to fit the project’s needs
early in the project development process.
In general, restoration projects go through the following phases:
Project Concept – project need and/or idea is identified. Conceptual project ideas can originate from previously
completed assessments, studies, strategic plans, etc. Project ideas can also come from local landowners,
stakeholders, scientists, user groups, restoration practitioners, agency staff, or just about anyone with
knowledge about a particular issue or location/site.
Project Development – Once a conceptual project has been identified and a project sponsor or project steward
decides to pursue the project, the project must be further developed before it is ready to pursue funding.
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Project development is a general term, and it can include more elements and processes than can be discussed in
detail here. In general, project development usually entails the following:
Identify project goals and objectives; Develop project scope; Develop project timeline; Develop project budget;
Continue outreach and collaboration with local stakeholders, agency staff, and tribe staff; and finally confirm
project feasibility based on regulatory compliance, landowner support, and local stakeholder support.
Project Funding – After project has been developed, is deemed feasible, and stakeholders have expressed
support, it is time for the project sponsor and project partners to apply for project funding via restoration-
focused funding sources (e.g., grant programs, foundations, donors, etc.). At this phase, the project sponsor and
partners identify the most likely funding source(s) where the proposed project will compete well (against other
restoration project funding proposals), and the project team drafts and submits grant proposal(s) to secure
project funding. This phase often entails securing funding from multiple funding sources, as many restoration
project funding programs require matching funds. Grant writing skills, persistence, and creativity may all be
required to be successful in this phase of the project.
Project Planning and/or Design – Now the project is funded, and this is when the project elements identified in
previous phases come to life. At this point, the project scope, timeline, and budget are put into action,
stakeholder outreach continues, and the project begins reaching some of its objectives. Multi-phase restoration
projects may complete a planning and/or design phase as a standalone Phase 1 project. These Phase 1 planning
projects usually require additional funding for future phase(s) to complete the project (e.g., Phase 2
implementation).
Project Implementation – This is often the most expensive, but also the most exciting phase of the project. This
is where restoration actions take place on the landscape. The implementation phase can entail manual labor,
hand tools, large machinery, and even helicopters. Implementation can occur relatively quickly and take just a
matter of days, but on the other end of the spectrum, implementation can take months or even years and
multiple implementation phases to complete.
Project Monitoring – Ideally, all restoration projects will have some level of pre-project monitoring and post-
project monitoring to track project effectiveness. Unfortunately, many restoration funding programs do not
allow for funding this monitoring phase, and the project team may need to find funding elsewhere or
collaborate with other entities that may be able to contribute monitoring efforts (e.g., agencies, tribes,
landowners, etc.).
In summary, carrying a project successfully through all of these phases in a timely and consistent manner is no
easy task and requires collaboration and support from local stakeholders. Leveraging the skills, knowledge,
expertise, and funding from an array of sources is often the key to success. Please see Attachment A for a list of
restoration-related capacities often required to complete a project.
Survey Results from Restoration Practitioners
In December 2020 MHRP project partner, Trout Unlimited, solicited local restoration practitioners, agency staff,
tribe staff, and stakeholders to complete a short survey. The intent of this survey was to engage those
experienced in local restoration efforts to gain insights regarding restoration history, current restoration
capacity status, and likely restoration capacity needs in the future.
Below are the four questions posed in the survey, and respondents had approximately six weeks to respond.
Respondents had the option to complete the survey online, or they could submit survey responses directly via
emailed word document. We received eight responses to the survey, and a summary of the responses is
displayed in bullets below each question (in no particular order):
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What are current strengths in local capacity to implement restoration projects?
Landowner knowledge of watershed, history, historic condition and change over time Existing strong knowledge base (e.g., agencies, tribes, NGOs, landowners, etc.)
Experienced organizations and resource managers have been and continue to complete
restoration projects Multiple funding programs currently exist (WA Restoration & Resiliency Initiative, Salmon
Recovery Funding Board, Brian Abbott Fish Barrier Removal Board, etc.) Heavy equipment expertise and availability
Wood locally available, especially racked on bars, but also standing in forests The participation and contribution to restoration, monitoring, and science from University of WA
Olympic Natural Resource Center (UW ONRC)
Good coordination and strong restoration project partnerships currently exist Existing project sponsors; local knowledge and relationships; project prioritization; functioning
Lead Entity Group incorporating technical and community members
Where are gaps or challenges in local capacity to implement restoration projects?
Lack of public outreach and landowner relationships Data gaps. Need to prioritize restoration actions on good data, not just available data. Need data
for non-salmon species (to inform restoration actions). Limited staff or staff time available to steward additional projects through the pipeline Grant writing (to secure project funding) Lack of local certified engineers
Over-engineering and cost for some types of projects Funding, especially for higher cost projects (e.g., road related issues, reach scale projects, etc.) Materials such as large wood with root wads or locally sourced native plants/seeds can be
challenging Many projects are large in scale, equipment-intensive, and impactful (not necessarily positive) Post-project lessons learned not shared regularly
Change occurs regularly – and project funding can be too late to implement as designed or for the
function intended.
Where do opportunities exist to increase capacity to implement restoration projects?
Continue/increase project partnerships (e.g., agencies, tribes, NGOS, landowners, stakeholders,
etc.) Increase project coordination at the ground level
Conduct focused assessments to close data gaps, promote proactive restoration project
development, and more shovel ready projects prepared for funding opportunities
Planning projects, like this MHRP Phase 1 project, and organized workgroups where many
shareholders can get together to focus in on specific areas and share knowledge increases
capacity Increase landowner outreach to educate them about potential opportunities, like funding and
support, to restore their property
Leveraging current capacity through strategic collaboration; developing and/or advancing strategic
restoration action plans; more shovel ready projects; streamlined permitting; untapped funding
sources
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Work with UW ONRC, Peninsula College, Tribes, Counties, and NGOs to fund internships,
fellowships, class projects, etc. Increase engagement and data sharing with UW ONRC T3 project and DNR’s Olympic Experimental
State Forest program More studies, data collection, and monitoring needed to better understand priority restoration
actions
What strategy is needed to pursue these opportunities and increase restoration capacity?
Need dedicated staff capacity for landowner outreach. Applicable outreach strategies currently
exist (Coast Salmon Partnership Outreach Strategy), however more capacity needs to be focused
to increase outreach efforts and meet outreach objectives.
Strategic coordination for long term data collection and management (e.g., tribes, agencies, local
stakeholders, etc.) Endowment fellowships and technical positions focused on the Western Olympic Peninsula
Education pathways; training & education incentives; awareness about restoration employment
and/or funding opportunity(s) Stable funding to support a resilient restoration economy; local support; engaging volunteers
Conservation easements for protected areas (that allow natural ecological processes) Increased monitoring to track trends and change over time Move infrastructure (e.g., roads, buildings, etc.) out of floodplains, where possible, or build the
riverbanks back (buffers) to maintain natural riparian function Collate data sets into a single searchable location to inform future work Build advocacy for the watershed that recognizes all the contributions made and interests
involved Coordinate a strategic outreach effort to educate communities about the less obvious benefits of
restoration, such as positive impacts to ecosystem services, fisheries, tourism, water quality,
summer stream flows/water quantity, etc.
Inventory - Local Capacity to Supply Restoration Needs
Please see Attachment A for a list of restoration-related capacity needs and Attachment B for an inventory of
available restoration-related businesses in the region. Attachment B is meant to be a living document, and we
anticipate it will be revised and become more conclusive over time. In compiling this inventory of local business,
we focused on the communities within WRIAs 20 and 21, and we consulted the following resources: Forks
Chamber of Commerce; WA Secretary of State; Google search engine; Personal communication with local
stakeholders and practitioners.
Things to Consider
Difficult to Quantify All Capacity
There are many capacity needs not discussed in detail in this chapter or associated attachments. Nearly all
restoration projects require administrative resources such as office space and equipment, internet connectivity,
travel/per diem expenses, fuel, meeting venues, meeting facilitation, etc. Restoration efforts can also call for
acquisition-related professionals for land appraisals, legal support, land conservation designations (e.g.,
conservation easements), environmental service technicians (for site assessments and testing), water quality
monitoring, etc.
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Additionally, some projects require materials that are unique, specialized, and/or not easy to procure. For
example, small- and large-scale projects often require a source for native plants and/or seeds appropriate for
the local ecosystem being restored. Another example would be Large wood and engineered log jam projects,
that aim to replicate the function of large fallen wood in the channel and floodplain. These large wood
restoration projects depend on a supply of mature trees (often with root wads attached), and the acquisition of
timber rights to conduct specialty harvest of mature second growth forests may be necessary to complete these
kinds of projects. In summary, it is important to consider the vast array of funding, infrastructure, materials,
administration, etc., beyond project-specific requirements when estimating the capacity needed to fulfill
restoration projects’ needs.
Climate Change
The ecology of the Olympic Peninsula’s West End is a unique and relatively remote, but it is also highly
vulnerable to the changing climate. Recent forest fires in a second growth and old growth forests of the Queets
and Quinault Watersheds surprised many. Heat domes and altered precipitation patterns are stressing trees
with implications for forest extent and productivity, river hydrology, and habitat quantity and quality for fish.
During June 2021, temperatures reached 98 degrees at the ONP Visitor Center and a record breaking 109.9
degrees at the nearby Quillayute Airport weather station. Along the Hoh Main Line and Maple Creek Road, the
new top growth of many Douglas fir trees were wilted during this heat wave. Currently, along many south-facing
road corridors, western red cedars, maples and other forest vegetation appeared heavily singed or desiccated.
These heat impacts were noticeable on July 24th2021, the date of the Middle Hoh River resiliency plan launch
event at the Fletcher Ranch, but were largely invisible by June 2022, after a particularly cool and wet spring that
year.
The Middle Hoh River is famous for its rainfall, mushrooms and mosses, but increasingly the area experiences
long periods of drought, with low summer river flows and higher water temperatures, as well as higher flood
flows and frequencies in winter. The glaciers that feed the Hoh River are receding rapidly and the risk of wildfire,
once almost unthinkable, is becoming a serious concern. Projects that anticipate and respond to new ecological
hazards associated with erratic and extreme weather events linked to climate change, and local expertise to
implement them, are needed to meet the challenges of an increasingly uncertain future. Local capacity to
respond to these needs would ideally be paired with economic activities designed to sequester carbon and
participate in larger efforts to rapidly reduce the earth’s temperature while carbon emission reductions continue
to accelerate. As a primary example, the grassroots MEER:ReflEction (meer.org) Framework developed by Dr. Ye
Tao at Harvard Rowland Institute offers a scalable approach to reducing the global temperature to help slow the
loss of ice, and associated methane emissions (a greenhouse gas twenty times more powerful than carbon
dioxide), in a manner that may also produce benefits for industrial agriculture. Ultimately, the success of
restoration activities on the West End will depend upon the world community’s embrace of actions to restore
the planet’s climate systems.
Increased Funding
As previously mentioned, the Washington Coast has experienced a relatively recent increase in restoration
funding from multiple agencies, grant programs, and/or foundations. As a result, our capacity to fill jobs locally is
in transition, and currently, much more is being planned, prioritized, and implemented than ever before. This is
largely due to the WA Coast Restoration and Resiliency Initiative grant program, and there are also substantial
federal funding increases on the horizon. This increase in funding is already providing opportunity to grow local
restoration capacity, restoration-related jobs and businesses, and increase the pace and scale of restoration
projects. These opportunities are anticipated to grow as available funding continues to increase.
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Discussion
For the first time in the Middle Hoh River, local stakeholders, restoration experts, agency staff, local and regional
jurisdictions, and vested interests have come together at monthly intervals for nearly two years to collaborate
and develop a plan to promote a vision for the long term resiliency of the Middle Hoh River corridor. Without a
doubt, the process of developing the draft plan has been a challenging task with many questions yet to be
answered. Regardless of these challenges, much progress has been made in identifying a path forward to restore
and/or protect the Middle Hoh in the face of constant change. Through many meetings, site visits, data sharing,
personal communications, etc., we now have a draft plan and strategic actions identified to realize a productive
and sustainable Middle Hoh River for the ecosystem and communities that call this special place home.
Reaching the objectives laid out in the recommended actions in MHRP will provide multiple benefits. For
example, restoration actions are intended to address threats to property within the corridor while also
promoting improved habitat for salmon, steelhead, and the surrounding ecosystem. Additionally, a healthier
and resilient Middle Hoh ecosystem will allow local communities and wildlife a greater ability to adapt to climate
change impacts, such as increased peak flows and mainstem Hoh River migration and avulsion events. It is
important to reiterate that the restoration actions recommended are intended to promote natural ecosystem
processes. Aligning with and promoting these natural processes is critical for creating and maintaining fish and
wildlife habitat and allowing the natural ecosystem the space and time needed to adapt to disturbance as well
as climate change. In other words, if we understand how to restore and/or take care of the Middle Hoh
ecosystem, the Middle Hoh ecosystem will be able to take care of itself in the long run. Looking ahead, a
resilient Middle Hoh will result in rebounding salmon and steelhead stocks and a healthy, mature riparian forest
ecosystem. This uplift has the ability to contribute significantly to the fast-growing tourism and recreation
economy the region is experiencing.
According to a 2015 report by the University of Oregon: Assessing, Planning, and Monitoring to Increase Local
Economic Opportunities from Restoration: “Increased interest in restoration on both public and private lands has
led to opportunities for advancing a more robust restoration economy in some rural communities. However,
achieving local economic benefits for businesses and workers may require deliberate strategies that are carefully
matched to local strengths and limitations.” To identify these strengths and limitations the report recommends
conducting a restoration industry assessment, similar to the research completed to inform this chapter. The
report explains: “A restoration industry assessment collects information about the state of the restoration
industry in a particular locale. It can include information about the types and amount of work undertaken in an
area, the businesses contracted to perform that work, and characteristics of the workforce implementing the
work. This information can act as a foundation for developing and implementing strategies that links forest and
watershed restoration work with the people and businesses skilled and equipped to undertake this work.”
Once a restoration industry assessment has been conducted, the report recommends the development of a
restoration jobs action plan as part of the strategy to link restoration projects to employers and businesses. The
report notes: “The action plan is likely to involve a number of strategies involving different groups and
organizations. For example, the action plan might include a federal lands strategy, a nonprofit contracting
strategy, and a contractor capacity strategy. Some strategies may be implemented quickly, whereas others
might take months or even years. Implementation is most likely to succeed when it becomes a regular part of the
work plan of local collaborative groups, nonprofits, and land managers.”
As a result of these recommendations, and the increased understanding as to the local restoration capacity
strengths and limitations, we are recommending the formation of a Restoration Economy Workgroup as a
subcommittee of the Middle Hoh Resiliency Leadership Team. This subcommittee workgroup would require
participation from multiple individuals and groups already active in developing the MHRP, but most importantly,
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it would need leadership from the local businesses and employers to drive the economic development strategies
to foster long-term economic uplift through a new and essential sector. Over time, this subcommittee could
coordinate with practitioners working in other major projects to foster a West End O.P. Ecologic Restoration
Program (or Sector) with representation on the West End Business and Professional Association.
The local business and expertise currently available to conduct restoration actions are certainly a strength
already being applied to work in the Middle Hoh and the West End. There are many restoration groups already
implementing successful restoration projects, and these projects are leveraging the skills of local contractors,
machine operators, forestry experts, etc. That said, there does seem to be limitations of locally available
businesses needed to develop, design, and implement restoration projects. Where these restoration capacity
limitations exist, local project sponsors generally have to contract businesses located outside of the region to
accomplish their restoration projects’ objectives. An example of this can be seen in the limitations of local
certified engineers to design and oversee implementation and construction of restoration projects. A likely
reason for these capacity limitations is often due to the relatively small and inconsistent restoration-related
work available in the region. In other words, there simply isn’t enough ecosystem restoration work available for
an engineering firm to set up shop locally and keep full time staff employed via WRIA 20 restoration work alone.
In researching this chapter, several interviewees noted that currently much of the resources/services needed to
complete a restoration project are imported into WRIA 20, and therefore much of the economics are exported.
To change this trend and promote local restoration economic growth would require an increase in restoration-
related work to the point that it could justify and sustain new local businesses (while also supporting existing
businesses). In short, the demand and funding for restoration jobs and expertise needs to exist locally at a level
to justify the supply of services (e.g., certified engineers).
A respected coastal economist provided feedback in the interview process, and they noted that currently,
restoration work itself is likely having minimal impact on the local economy as the work is temporary and labor
is often imported from out of the region. They also recommended focusing on the indirect impacts of
restoration work as having the greatest benefits to the local economy – restoring salmon habitat can positively
impact the local economy through increased recreational opportunities, commercial opportunities, as well as
cultural benefits. These elements also attract tourism seeking those attributes to the region, which can bring
additional dollars to the economy.
Another potential restoration capacity limitation appears to be clear, locally available career path opportunities
for those interested in education, training, experience, and employment in the field of ecosystem restoration.
The region is rich in history of commercial forestry and commercial fisheries, however these industries have had
to adapt to changing markets and limited availability of natural resources (e.g., depressed fish stocks, loss of
mature forest stands). The businesses, organizations, families, and individuals that historically did this work are
very skilled and knowledgeable of working on the landscape, and many of these skills could be applied to
restoration work with available incentives and/or opportunities. Working with these industries in a collaborative
manner to reach ecosystem restoration goals is an incredible opportunity worth pursuing. For example, several
recent salmon and steelhead habitat restoration projects have contracted construction contractors that were
formerly timber harvest contractors. These contractors have intimate knowledge of the area and the experience
to move about and work on the landscape. Awareness and consistency of available work/contract opportunities,
as well as awareness of training, certification, and career path opportunities, appears to be a limiting factor for
further developing these relationships between skilled local businesses and residents and the field of ecosystem
restoration.
Available funding for restoration projects is another factor limiting the local capacity to supply restoration
needs. As previously noted, the relatively small and inconsistent nature of restoration work in the region is not
likely having a significant impact on the local economy. Increased and consistent funding aimed at restoring the
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region’s ecosystem function would likely have positive influence on several other restoration capacity limiting
factors. For example, consistent restoration funding would increase the rate and scale of restoration projects
implemented in the area, and therefore increase the justification for restoration-related businesses to operate
and be housed locally. The current Infrastructure Investment and Jobs Act currently (as of August 2021) moving
through the House and Senate includes $1 billion to correct culvert fish barriers and $172 million for the Pacific
Coastal Salmon Recovery Fund. If this bill is passed, this would be a noticeable increase in restoration funding to
the region and provide increased opportunity to grow local restoration capacity in WRIA 20.
Many restoration projects currently being implemented in the region are labor intensive. Related to the need for
an increase in consistent funding is the need for more skilled labor trained and capable to do the work needed
to reach restoration objectives. Local nonprofit organization, 10,000 Years Institute, is currently working to
develop and fund a Coastal Conservation Corps. The goal of this program is to create stable employment
provided by a continuously funded program to conduct place-based, persistent, year-round work via trained and
skilled resource workers. The program would aim to support resilient natural resources industries and
ecosystems, promoting stable employment and communities. Types of work the Coastal Conservation Corps
aims to engage in include: invasive species detection, monitoring, and management; forest stand treatments
and biochar pyrolysis; habitat restoration, such as revegetation, wood placement, fish barrier correction, etc.;
recreation via trail and facilities maintenance, signage, etc. This is an example of how consistent restoration-
related funding would increase the number of restoration-related jobs in the area while also increasing the
range of positive benefits from restoration actions.
Recommendations to Increase Local Restoration Capacity
Assess the desire and feasibility to increase restoration-related jobs and business (capacity) in the region
in collaboration with local stakeholders, restoration practitioners, and the local business community.
Develop a Restoration Economy Workgroup as a subcommittee of the Middle Hoh Resiliency Leadership
Team. If developed, the Restoration Economy Workgroup could work towards a program and funding of
a comprehensive West End O.P. Restoration Program. This is a similar idea to the Coastal Conservation
Corps proposal that 10,000 Years Institute is working towards. The West End O.P. Restoration Program
could work with the local education programs to develop clear career pathways and incentives for those
interested in the field of restoration. The program could also work with local groups to promote
economic growth and stability (e.g., West End Business and Professional Association), and this would act
to attract new restoration-related businesses and services to the local communities.
Develop outreach, training, incentives, and opportunities for local contractors not yet experienced in
restoration actions that take place within stream channels and floodplains (e.g., installation of
engineered log jams).
Develop strategy(s) to take advantage of increasing restoration project funding opportunities. This
strategy(s) would promote a proactive approach and be prepared with high priority, locally vetted,
shovel ready projects before funding opportunities arrive (e.g., West O.P. Barrier Prioritization Project
and Wild Salmon Center, Coast Salmon Partnership, and Trout Unlimited’s Cold Water Connection
Campaign).
Increase the capacity and ability to incorporate climate change resiliency into restoration project design
and implementation. Increased connection between climate change trends and restoration objectives
will promote more climate resilient restoration outcomes. Projects that anticipate and respond to new
ecological hazards associated with erratic and extreme weather events linked to climate change, and
local expertise to implement them, are needed to meet the challenges of an increasingly uncertain
future.
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PHASE II APPROACH
To realize the potential of this Resiliency Plan, the formation of a permanent group of individuals (Middle Hoh
Resiliency Initiative) is needed to ensure all groups working in the community are working together in a
coordinated effort toward the common vision(s) articulated in the desired conditions. This group should include
at a minimum several local landowners, the Hoh Tribe, Jefferson Co., local non-profits and conservation
organizations, recreational users and agency representatives to further ensure any potential actions are vetted
and considered openly and news can be communicated. The group will be needed to initiate and develop the
additional plans needed to realize the desired future conditions, as well as coordinate to help locate funding
sources for individual projects.
While the Action Plan (Appendix B) identifies specific opportunities and prioritizes their implementation, there is
additional, more detailed planning and study needed to move specific elements of the resiliency plan forward in
a coordinated and informed manner. Completion of these studies and plans will provide a framework for moving
forward larger components of the Action Plan that require additional information and/or coordination. This
additional work described as part of Phase II should proceed significant implementation of the Action Plan.
Each of the 5 project reaches of the Middle Hoh should have a more detailed Action Plan developed that could
provide a more detailed and site-specific plan for restoring the specific reach of the river. Reach specific Action
Plans would be collaboratively developed with the Hoh Tribe, local landowners, and resource agencies to find a
shared vision for each reach that addresses the needs for salmon and the surrounding community. Each plan
would prioritize work areas, or phases, for sequenced implementation in a matter that optimized resources and
local constraints.
The Lower Hoh River would benefit from having a similar Resiliency and Action Plan to better prepare the
community and river corridor ecosystem from the current and worsening climate crisis. A Resiliency Plan for the
Lower Hoh River would be led by the Hoh Tribe, rely and build upon the findings of this Plan, and include similar
inventories to characterize existing conditions and evaluation of specific trends and associated impacts.
Formation of a steering committee including a similar spectrum of representatives as this Middle Hoh Resiliency
Plan will greatly benefit development and ultimately adoption of the Plan. The protection of existing salmon
habitat, restoration of degraded habitat, and actions aimed to improve ecologic resiliency from impending
changes to the river corridor should be a primary theme throughout the document. Improving and/or
eliminating interactions with the river corridor and Highway 101 to the south and Oil City Road to the north
should be a major component of the Lower Hoh River Resiliency Plan. Because the lower river is within tidal
influence additional considerations for predicted sea level rise should be incorporated into the evaluation of
trends and anticipated changes. Predicted increases in flood magnitude and frequency, sediment supply and
rising sea levels will result in increasing flood and erosion risk to the community as well as alter floodplain and
instream salmon habitat. Development of a Lower Hoh Action Plan would outline specific actions to meet the
goals of the Resiliency Plan, and be developed collaboratively with all plan stakeholders.
The anticipated changes to the sediment and flow regime of the Hoh River resulting from climate change is not
well constrained and should be a primary consideration for planning purposes. One of the more pressing studies
needed is an in-depth evaluation of the anticipated flow and sediment regime changes in the Middle Hoh
related to climate change. Warming temperatures coupled with changing weather patterns will alter the rate of
surficial processes and sediment production, both of which are anticipated to increase the sediment load
entering the Middle Hoh. Flood flows are predicted to increase in magnitude and frequency, and summer base-
flows are anticipated to diminish. A better understanding of how these changes will manifest on the landscape
over time would greatly benefit the work completed and inform future planning efforts.
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A comprehensive survey of side channels within the Middle Hoh would further inform and refine prioritization of
floodplain habitat protection and enhancement within the reach. A complete inventory of the side channels
present and their habitat and hydrologic character, fish usage and riparian conditions would facilitate a more
informed decision about the properties to target for preservation and where and what restoration actions are
needed. Having functional off-channel habitat is critical to maintain anadromous salmon populations in the
Middle Hoh and needs to be a critical component of the overall restoration strategy.
The state of the riparian forest corridor along the Middle Hoh largely dictates the health of the fish using the
river. While the Hoh is known internationally for hosting ancient old-growth forests, these are largely confined
within the boundaries of ONP. Along the Middle Hoh, most of the riparian corridor has been logged at some
time in the past and is in some state of forest succession. A more detailed and complete Riparian Forest Plan
could more deeply integrate silviculture actions with invasive species management and restoration actions into
a cohesive strategy that can be implemented throughout the reach.
A comprehensive plan for the Upper Hoh Road is needed to layout a shared vision for what the road should be,
that best serves the people that use it and the surrounding environment. The plan should explore opportunities
for relocation, abandonment, improvements or some combination(s) thereof to the road that could improve the
user experience and reduce environmental impacts and risks. Identifying an improved alternative route out of
the northern side of the valley should be included in the plan for the Upper Hoh Road to improve community
resiliency. Hoh Tribe, Jefferson County, ONP representatives and the local community are critical stakeholders in
developing any future plan(s) for improvements or relocation of the Upper Hoh Road.
Recreation Plan to explore opportunities for larger recreation features (trails), ensure visitor use does not
detract from the environment (garbage?), and the number, location and types of day-use areas along the river
(including boat launches). Bring together local community, guides, day-users in community, NPS, county and
landowners to explore alternatives that can improve the experience for everyone while maintaining the
wildness of the river (limited paved parking areas).
While outside the geographic scope of this plan, it would be advantageous for there to be an agreement with
ONP and the Hoh Tribe to allow restoration actions within the park, and to establish emergency road repair
protocols to minimize the need for mitigation.
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