HomeMy WebLinkAboutMHRRP Appendix B JULY 2022
Photo: Raena Anderson, 10,000 Years Institute
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, Phil Roni, Kevin Fetherston, Paul Pittman, Luke Kelly, Jill Silver and Tami Pokorny
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.
June 2022
TABLE OF CONTENTS
Introduction 1
Proposed Actions 4
Lessons Learned 4
Education, Outreach and Engagement 6
Access and Recreation 6
Valley Development 6
Full and Partial Acquisitions and Relocation Actions 9
Instream & Floodplain Restoration 10
Riparian Restoration 10
Invasive Plant Prevention and Control 11
Engineered Log Jams and Large Wood Placement 12
Opportunities to Support Middle Hoh River Resiliency 14
Huelsdonk-South Fork Reach 14
Spruce Canyon Reach 15
Morgan’s Crossing Reach 15
Willoughby Creek Reach 17
Oxbow Canyon Reach 18
Prioritization & Sequencing 19
Prioritization Framework 19
Action Sequencing 21
Conceptual Restoration Strategy 21
Lindner Complex Reach 23
Upper Lindner Complex Sub-Reach Concept Design (RM 22.4-23.2) 24
Middle Lindner Complex Sub-Reach Concept Design (RM 21.5-22.4) 26
Lower Lindner Complex Sub-Reach Concept Design (RM 20.8-21.5) 27
Fletcher Ranch/TNC Sub-Reach (RM 27.3-28.3) 28
Brandeberry/Lewis Sub-Reach (RM 28.7-30.0) 30
References 33
LIST OF TABLES
Table 1. Hoh River Valley. 1
Table 2. Actions Identified and scored with respect to improving resiliency in the Middle Hoh (0=no resiliency benefit, 10=most resiliency benefit). Scoring is based on current conditions
and can change in the future depending on changing conditions and stakeholder priorities. 20
LIST OF FIGURES
Figure 1. Old bridge crossing of the main stem Hoh River, 1942.2 Note size of logs being harvested. 3
Figure 2. Rock lined bank (riprap) protecting Upper Hoh Road taken at RM 24.6. Looking downstream at right bank. Guardrail along road is visible at top of right bank. Flow is from left
to right. Oct. 2, 2020. 5
Figure 3. Example typical clearing for opening canopy and planting conifer. 10
Figure 4. Residential cabin at imminent risk of damage on left bank of river looking upstream near RM 29, Nov – Dec 2020. 14
Figure 5. Wide active channel with young alder forest along the channel margin with active bank erosion near RM 29.9, Oct 2, 2020. 15
Figure 6. Young conifers planted in young monotypic stand of red alder near RM 22.8, Mar. 3, 2021. 16
Figure 7. Second-growth conifer recruitment on left bank at RM 24.1, Oct. 1, 2020. 16
Figure 8. Mixed forest age and wide unvegetated active channel at RM 19.5, Oct. 2, 2020. 17
Figure 9. Confined Oxbow Canyon reach with bedrock walls at RM 16.5, Oct. 2, 2020. 19
Figure 10. The Lindner Complex Reach and boundaries of sub-reaches (RM 20.8-23.2). 23
Figure 11. Conceptual restoration plan for the Upper Lindner Creek Floodplain (RM 22.4-23.2). 25
Figure 12. Conceptual restoration plan for the Middle Lindner Creek Floodplain (RM 21.5-22.4). 26
Figure 13. Conceptual restoration plan for the Lower Lindner Creek Floodplain (RM 20.8-21.5). 28
Figure 14. Conceptual restoration plan for the Fletcher Ranch/TNC Sub-Reach (RM 27.3-28.3). 30
Figure 15. Conceptual restoration plan for the Brandeberry/Lewis Sub-Reach (RM 28.7-30.0). 32
INTRODUCTION
The Hoh River is one of the better-preserved rivers in the United States. The 2020 State of Our Watersheds Report (state-of-our-watersheds-sow-2020-final-web.pdf at nwifc.org), recognized
that high road densities, fish passage barriers, timber harvest rates, invasive species, streamflow extremes, water quality and climate change “may pose a significant impact to salmon
runs in the Hoh River”. The river valley is geographically subdivided into three segments: Lower, Middle and Upper (Table 1). The focus of this report is on the Middle Hoh.
Table 1. Hoh River Valley.
SEGMENT
RIVERMILES (RM)
DESCRIPTION
Lower Hoh
0-15.6
Pacific Ocean to SR 101 at Oxbow Canyon
Middle Hoh
15.6-30.0
Oxbow Canyon to Olympic National Park
Upper Hoh
>30
Olympic National Park
The Hoh’s headwaters begin on Mount Olympus and the river flows west to the Pacific Ocean. The watershed is unique in the high quantity of precipitation it receives, the forests of huge
trees that grew at lower elevations, and the broad central valley with extensive and diverse floodplain habitats. The river’s flow regime is driven by winter rainfall and spring snowmelt.
The watershed’s steep upland sand glaciated headwaters contribute large amounts of sediment to the river which together with its high flows result in a dynamic river channel that moves
across much of its valley. Due to the loss of floodplain structure formerly supported by standing forests and accumulations of downed logs, only in confined portions of the valley associated
with bedrock constrictions or glacial moraines, is the river’s channel relatively stable.
The Hoh Tribe has resided in the Hoh valley for millennia, thriving on the abundant salmon and natural resources. “The Hoh Tribe is a river-based fishing community that is dependent
on the fish, wildlife and other natural resources of the Hoh River watershed for their subsistence and commercial economy. Therefore, protection of the watershed’s functions is key
to meeting the cultural and economic needs of the tribe.” (NWIFC 2020)
The river is home to all five species of Pacific Salmon: King, Coho, Pink, Sockeye and Keta (Chum), steelhead, along with Bull Trout, Cutthroat Trout, Pacific Lamprey, and many other
native species. The river has no dams (although a dam in the Oxbow was seriously considered at times from the 1930s to the 1960s) and no major water diversion facilities. The most significant
changes to the landscape began with European homesteading, followed by industrial timber extraction and road construction. Road and culverts occur throughout the Hoh valley from its
outlet (RM 0) to the Olympic National Park (ONP) Hoh Rainforest visitor center and campground at RM 36. Historic timber harvest occurred throughout the entire valley of the Lower and
Middle Hoh along with some clearing on the valley’s northern side within ONP associated with roads and development. Native old-growth forests have been protected within ONP. Timber
harvest outside ONP removed most of the largest trees within the Middle Hoh valley where only small isolated patches of old-growth remain. The most recent impact has been the introduction
and proliferation of invasive non-native plants. Land ownership within the Middle Hoh is a patchwork of private (residential and corporate), non-profit conservation organizations, county,
state and federal agencies. Much of the valley bottom lies within the river’s floodplain and channel migration zone (CMZ) which protects existing forests.
The large trees once common in the Hoh played an important role in the morphology of the river valley. When large trees fall into the river, they affect fluvial processes that form and
sustain aquatic and riparian habitat. Thus, the loss of these old trees has resulted in a wider more dynamic river channel and reduction in stable side channel habitat important to
salmonids. Mature floodplain forests are more resistant to bank erosion than areas with small trees. They benefit from lower erosion rates due to the large trees that fall into the
river when
erosion begins, reducing the erosive forces acting on banks as a result. Small trees simply wash away and are associated with high bank erosion rates. The large wood also forms logjams
that protect patches of floodplain where trees can mature and provide a future source of large wood. The logjams also create and sustain stable side channels that are critical to Chinook,
Coho and other key species. The loss of mature forest in the Middle Hoh valley, particularly on the floodplains and adjacent slopes, has contributed to more rapid channel migration
and loss of important side channel habitat. It also has increased risk to infrastructure, businesses and homeowners in the valley.
Road construction and maintenance has been another major impact to the Middle Hoh River, with the Upper Hoh Road extending an additional six miles into ONP. Floodplain roads disconnect
habitats such as side channels and wetlands, and reduce the potential for long-term large wood recruitment. The most common method to protect and repair the Upper Hoh Road from erosion
is to cover a bank with large rock (riprap). This technique captures the channel along the ‘hard edge’ and simplifies the river’s morphology into a linear channel along the bare rock,
which directly impacts rearing salmon habitat by eliminating hydraulic refugia (areas of slower water), cover and bank-sourced prey. It also prevents the natural recruitment of large
wood.
The Middle Hoh River community includes the Hoh Tribe, other local residents, timber corporations, privately- held timberlands, Washington State Departments of Natural Resources (WDNR)
and Fish and Wildlife (WDFW), The Nature Conservancy – a major landowner, additional non-profits, fishing and rafting guides, tourists, Jefferson County, Olympic National Forest and
ONP. All have an interest in the natural function and productivity of the Hoh River, as well as the valley’s ecosystems, biodiversity and fish populations.
Even though the Hoh watershed receives the most precipitation of any watershed in the continental United States, the basin’s forest cover acts as a sponge to moderate the flow of water
over the landscape. Prior to the 20th Century, extensive forests and deep soils helped attenuate the rate stormwater flows from uplands down to the river. Meanwhile, the path of main
stem river channel itself was governed by large tracts of mature conifers growing on the floodplain and along the shoreline. These trees and forests presented a formidable force that
effectively countered the river’s erosive power. Where very large trees did fall, they functioned as the nucleus of enormous log jams that would, in places, split the flow of the main
channel into multiple, much less powerful threads. Into these threads, additional trees would eventually fall, causing scour pools. Beaver often colonized islands between the threads
and, especially in locations of ground water upwelling, pools of cold water sustained salmon during extended periods of hot weather and otherwise low water.
Outside ONP, the native old-growth forests have been replaced by industrial forestlands. The most significant period of timber harvest began in the 1940s and extended into the 1990s
(Figure 1).
“It was not until a railroad line from the mills at Port Angeles began to snake toward the small town of Forks in the first decades of the twentieth century that lumber became a significant
economic activity on the western edge of the Olympic Peninsula. There the industry experienced a series of booms beginning with the First World War—when the area was logged for the
spruce used in aircraft construction; in the 1920s as the demand for pulp-woods rose; and then, sustained growth from the Second World War peaking in the 1970s when a convergence of
market demand and liberal federal policies opened large tracts of public lands on the peninsula to logging. Also,
advances in technology, particularly high-lead yarding, the chainsaw, and the growing use of trucks made it possible to profitably log areas that in earlier years would have been bypassed.”
/
Figure 1. Old bridge crossing of the main stem Hoh River, 1942.2 Note size of logs being harvested.
The cumulative impacts of these practices over decades, in particular the extensive, intensive harvest of old growth forests, road building and bank armoring along the Upper Hoh Road,
have altered the natural processes that formerly supported abundant runs of salmon and steelhead. These natural processes perfectly melded climate, vegetation, geology, water, and sediment
into exceptional biodiversity and fish abundance. Timber harvest provided jobs but came at a high cost with respect to native ecosystems and the river, particularly during the latter
half of the twentieth century, when clearcutting steep slopes led to numerous landslides and
debris flows. While forest practices have improved in the last twenty years, impacts still occur. Substantial areas in the watershed and Middle Hoh valley have been set aside for conservation
but it will take centuries to fully recover without restoration action to accelerate the process. Future ecosystem recovery is also being impacted by invasive plants and the warming
climate which has already begun to have significant impacts within the watershed. Recent scientific estimates predict that all of the alpine glaciers on the Olympic Peninsula will be
gone by 2070. Today, the experiences of all residents and visitors to the valley are impacted to one degree or another by flooding, erosion, or the decline of fishing opportunities.
Beginning in the 1800s, families originally from Europe built farms, vacation homes, roads and businesses with an understanding of the river’s dynamics gained through experience and
observation. They often maintained wide forested buffers between the riverbank and their farms or homes, built on the highest ground available.
Few rivers, including the Hoh, have comprehensive management plans that integrate the diverse members of the community in decision-making and developing a common vision for the river.
While there are state and federal programs that offer educational resources, few counties have budgets for outreach programs. The Middle Hoh Resiliency Plan (Plan) was developed with
the intent to establish better communication with local residents and set up a framework to continue outreach into the future working with other public, tribal and non-profit organizations.
A key goal of the Plan is to establish a “living document” and framework for community communication, education and decision-making regarding river management, habitat restoration,
flood protection, and conservation that can be sustained permanently. Continuing to advance the Plan, and to identify trends, maintain momentum, and address cumulative changes to the
watershed, will depend on securing funding over the long-term specific to this intent. Project-level funds also provide the opportunity to advance prioritized action items in this Plan
through coordination with the North Pacific Coast Lead Entity (NPC LE) and Coast Salmon Partnership (CSP).
This Plan provides a series of prioritized actions developed to provide long-term resiliency for the ecosystem of the river and the community that calls it home. The findings of the
Plan were compiled to identify proposed actions focused on the casual mechanisms contributing to higher channel migration rates, loss of mature floodplain forests, loss of key aquatic
habitats, the sustainability of existing infrastructure, and risks to property owners within the valley. With stakeholder feedback, the proposed actions were further developed, refined,
and ranked to provide a prioritized sequence of actions to realize the goals of the Plan. This Plan’s recommendations will be integrated, as appropriate, with the NPC LE and CSP’s guidance
documents as they pertain to the Hoh River.
PROPOSED ACTIONS
Education is the critical first step in fostering a shared understanding of the dynamic and ever-changing interaction between rivers and their floodplains, and the inherent risks posed
by living in their proximity. Thoughtful and honest conversations between floodplain residents and restoration practitioners will support advancing the long-term vision for the resiliency
corridor (Appendix D, Map 9).
Lessons Learned
The Hoh Valley is home to one of the few temperate rainforests remaining and some of the largest trees in North America. Historic logging outside ONP has accelerated upland erosion,
particularly from landslides and debris flows (Parks 1990). Logging in the valley bottom removed big trees that were critical to defining the river’s morphology, habitat, and ecosystem
complexity. The loss of those trees led to a more simplified river, more prone to rapidly migrating across its broad alluvial valley, which is more than 4,000-ft wide in some areas.
(e.g., Montgomery and Abbe 2006, Abbe and Brooks 2011, Collins et al 2012, Abbe et al. 2016). While residential
land development is rare in the Middle Hoh valley, the few areas that have been developed are subject to significant erosion risks and damage. Other major impacts are road construction
and maintenance that have disconnected the river from portions of its floodplain and altered the natural river banks as well as the proliferation of invasive plant species that degrade
native riparian vegetation, influence channel morphology and impact habitat formation.
Over the last 30 years, major changes in our understanding of land management impacts to rivers have led to new regulations to improve management and protect native species. Forest practices
have evolved to better protect riparian areas, floodplains, CMZs and unstable slopes. Portions of the Hoh floodplain have been conserved by land trusts and non-profits. Floodplain forestry
to promote conifer development and restore the native big trees has become an important objective of land management within the valley. An essential element of current land management
is invasive plant control, work that has been led by the 10,000 Years Institute, based in Forks, WA and has been funded entirely by grants. Perspectives on riverbank alteration have
also changed, particularly the negative impact of traditional rock revetments on fisheries and habitat formation (e.g., Schmetterling et al. 2001). Significant portions of the Hoh
River’s banks have been converted to rock revetments to protect the Upper Hoh Road (both in and outside ONP) (Figure 2). Recent research has shown alternatives such as engineered logjams
have been successfully applied to protect infrastructure and are much better at emulating natural river banks, enhancing aquatic habitat and preserving forest buffers along the river
(e.g., Abbe et al. 1999, Abbe and Brooks 2011, Abbe et al. 2016, Abbe et al. 2018).
While hundreds of millions of dollars have been spent restoring aquatic habitat around Washington State, no restoration projects have been constructed on the mainstem Hoh, with the exception
of invasive plant prevention and control since 2001. Restoration actions in the Upper Quinault River over the last 10 years have been instrumental in restoring floodplain forests and
side channels crucial to the native Blueback Sockeye fisheries, which were reopened for harvest in 2021 after being closed for years.
Habitat deficits in the Middle Hoh require many of the same actions proven to be successful in restoring habitat in the Upper Quinault. Recent changes to regulatory guidelines, more
environmentally sensitive land management and restoration actions are helping to better protect and restore aspects of the Hoh River, but more active restoration actions are needed,
along with efforts to assist local willing landowners to reduce their risks by relocating out of hazard areas, and acquisition or protection strategies that preserve native habitat.
All these actions are critical to sustaining the natural infrastructure of the Hoh River valley. Developing the Plan and engaging local stakeholders has already significantly increased
shared information, communication and transparency in management decisions influencing the Middle Hoh River. Sustaining the Plan and its leadership
team will be crucial in securing future funding and benefiting the local community and protecting one of the “Last Great Rivers” in the United States.
Education, Outreach and Engagement
The Middle Hoh community represents a diverse collection of individuals with a varied background and life experiences, with a range of concerns from the health and condition of the Hoh
River ecosystem to channel migration, traffic and frequent washouts of the Upper Hoh Road. Most are well-aware of the flood and erosion hazards, while river processes and aquatic habitats
needed to sustain salmon populations are less understood. While there are state and federal programs that offer educational resources, few counties have budgets for outreach programs.
The Plan was started with a grant intended to establish better communication with local residents and set up a framework to continue outreach work into the future working with other
public, tribal and non-profit organizations.
The Plan established the Middle Hoh steering committee comprised of key community members to discuss management issues at regular meetings. This public forum should be maintained to
disseminate information and notify the community of any studies, planning, or actions being considered within the river valley. It is imperative that agencies such as the Federal Highway
Administration, ONP, and Jefferson County Public Works use this forum to discuss any issues involving the Upper Hoh Road to notify the group before any studies or actions are implemented.
In the past, failure to communicate has led to serious environmental impacts and a lack of trust by community members.
Access and Recreation
Tourism and fishing are crucial economically to the local Hoh watershed community and larger west-end coastal region of the Olympic Peninsula that includes Clallam, Jefferson, and Grays
Harbor Counties. Maintaining recreational access to the Middle and Upper Hoh is essential to the Hoh Tribe, local communities and thousands of tourists that come from around the world.
River restoration projects across Washington State have not only improved aquatic and riparian habitat, but they have often improved public access. Maintaining transportation infrastructure
through the Middle Hoh is also critical to ensuring emergency services are available to residents and visitors. The Upper Hoh Road has often been threatened or damaged by the bank erosion
associated with the migrating Hoh River channel. Traditional road repairs have used large rock embankments or “riprap” which simplifies the river’s shoreline, eliminates riparian shade
and wood recruitment, and destroys the river’s natural appearance. Riprap has also been found to adversely impact salmon habitat. New riprap was just placed in ONP to protect the road
in the winter of 2022. Major advancements in more environmentally sustainable and fish friendly approaches to bank protection such as engineered logjams and complex timber revetments
have been shown to not only improve fish habitat, but to provide better erosion protection. Wherever possible, road segments at risk of erosion should be relocated outside the resiliency
corridor. Engineered logjams have even been used to protect boater access since their leeward (downstream) side creates a natural ramp down to the river. Unimproved (4x4) access for
experienced guides to launch and retrieve their boats should be maintained and re-established in appropriate locations when river changes eliminate access at existing sites. Any actions
regarding access should be closely coordinated with the Hoh Tribe, local landowners and guide community. Feedback from the local community indicates there is concern related to improving
access to the river, potentially leading to more inexperienced people using the river and an increased risk of personal injury.
Valley Development
Much of the historic development in river valleys throughout the country did not take into account flood and erosion hazards. This has resulted in billions of dollars of damages and
the loss of lives and property. Local
examples include the numerous washouts of the Upper Hoh Road and structures damaged or lost to bank erosion in the Brandleberry community (just downstream of the South Fork Hoh confluence).
Natural intact valley bottoms provide the most ecologically diverse and productive land in a watershed. Unlike most human development, native ecosystems are well adapted to flooding
periodic erosion and sedimentation. Focusing development in upland areas outside the risk of flooding and channel migration is the best strategy for building and sustaining resilient
communities. This also reduces the costs to protect or rebuild. In the last 30 years tens of millions of dollars have been spent to protect the Upper Hoh Road. The Plan delineated a
Resiliency Corridor to identify areas susceptible to flooding and erosion. Focusing on conservation and restoration within the Resiliency Corridor will improve the river’s ecological
resiliency and its ability to adapt to larger floods and other changes resulting from the warming climate. The steep slopes along the Hoh valley present additional challenges to development
and are certainly not suitable for infrastructure or homes, but there are numerous upland sites outside the Middle Hoh Resiliency Corridor that offer relatively level land which are
safe from flooding and erosion. Identifying these areas is crucial if new development is considered within the valley. Population growth is affecting all of Washington State, including
the Olympic Peninsula. Thus, it is never too early to begin planning and zoning that encourages sustainable development in areas safe from natural hazards and outside ecologically sensitive
areas.
Road maintenance has had the single largest impact to aquatic and riparian habitat other than historic logging. A major improvement begins with better communication between the government
agencies responsible for roads (Federal Western Lands, Federal Highway Administration; ONP, and Jefferson County Public Works) and the Middle Hoh community (Hoh Tribe, landowners, US
Forest Service, WA Department of Natural Resources, WA Department of Fish and Wildlife, The Nature Conservancy, and others) represented in the Middle Hoh steering committee and technical
leadership group.
Wherever roads are located within the resiliency corridor, the first option should be to relocate the road outside the corridor. If this isn’t possible, actions to protect the road should
incorporate erosion measures that create a complex shoreline with velocity refugia and cover using engineered logjams and by re-establishing a forested riparian buffer between the road
and the river. Rock “riprap” embankments should be abolished entirely, even in emergency situations. Riprap has eliminated miles of the Hoh River’s natural shoreline. All road and
riverbank protection strategies should also include restoration of a functional forest buffer between the road and the river.
The costs of flood damage to lives and property, along with environment and economic benefits of restoring floodplains, has led local, state, and federal government agencies to implement
major land acquisition and relocation programs across the country (e.g., Conrad et al. 1998, FEMA 2009, Polefka 2013, Mechler et al 2014, Schiff et al. 2015, Frendenberg et al. 2016,
ELI 2017, Patterson 2018, Salvesen et al. 2018, Siders 2019, Johnson et al. 2020). More locally, Pierce County has implemented very successful buy-out programs in floodplains of the
Puyallup and Carbon Rivers.
Helping people get out of harm’s way not only protects their lives and properties but can save taxpayers millions of dollars in flood relief. Managed retreat from increasingly hazardous
areas, such as the purchase of flood prone property, will become an unavoidable situation as climate change effects intensify (see Jay et al, 2018 in https://nca2018.globalchange.gov/).
The federal government shares responsibility for flood recovery and there is increasing interest in assisting state and local governments with reducing community flood risk.
A comprehensive list of federal flood resilience and risk reduction assistance programs is provided in a recent 2019 Congressional Research Service report, https://crsreports.congress.gov,
report number R45017. There are also several other federal resources to assist the County in developing the programs and support structures necessary to provide the Middle Hoh landowners
with viable options for relocation, including but not limited to:
Repetitive Loss Program: Using FEMA’s Cost-Benefit Calculator, “beneficial” actions for repetitive loss properties (more than 1 FEMA insurance claim) can be identified. This opens funding
opportunities and reduces community insurance premium costs (including for floodplain residents).
Hazard Mitigation Grant Program: This program funds buyouts for homes and businesses that meet the cost-benefit ratio. https://www.fema.gov/hazard-mitigation-grant-program
NRCS Conservation Programs: US Department of Agriculture programs help landowners reduce soil erosion, enhance and improve water quality, reduce flooding damages, and increase wildlife
habitat. https://www.nrcs.usda.gov/wps/portal/nrcs/main/national/programs/
Washington Coast Restoration and Resiliency Initiative (WCRRI): WA state program to address the coast regions highest priority restoration and resiliency needs with opportunity for landowners
to protect property while restoring and enhancing habitat. https://rco.wa.gov/grant/washington-coast-restoration-and-resiliency-initiative/#
The federal government is increasingly pushing for communities to commit to buy-out programs in chronic flood-prone areas (Mach et. al 2019). In a recent federal policy change, funding
partially administered by the U.S. Army Corps of Engineers for flood protection and climate adaptation can be contingent on local governments agreeing to use eminent domain to purchase
properties whose owners are unwilling to voluntarily sell: https://www.nytimes.com/2020/03/11/climate/government-land-eviction- floods.html?action=click&module=Top%20Stories&pgtype=Homepage.
Such policies and initiatives promote a process to identify the risks and impacts on community resilience to natural hazards, including those associated with climate change, and direct
Federal agencies to support climate resilient infrastructure, including a Hazard Mitigation Assistance (HMA) program by FEMA, which provides funding for flood mitigation strategies
rooted in restoring ecological process and function. See: https://www.fema.gov/media-library-data/1487161136815-ecad1c0312eda2111ffa28735a4d06ad/FSR_Fact_Sheet_Feb2017_COMPLIANT.pdf
Other actions the County could pursue in support of landowner relocation assistance include:
Prohibit “emergency actions” that degrade habitat.
Encourage road re-location outside the resiliency corridor where and when possible. When bank protection is necessary utilize physically complex structures such as engineered logjams.
Establish funding for immediate acquisition of flood prone properties that come up for sale.
Develop preliminary criteria for prioritizing acquisitions
In many locations, the current cost of floodplain land acquisition is 3 to 5 times less than future flood damages (Johnson et al, 2020).
Develop long-term plans for moving interested residents to safe ground, including considerations such as:
Establish an outreach program to assist landowners who want to stay in the community but move out of flood prone areas.
Ensure adequate services and access to local and county roads in plans for relocation.
Local government action guides exist which provide detailed guidance and resources for developing a floodplain acquisition program which maximizes ecological benefits and minimizes risk
as projects are planned and completed (ELI 2017).
Consider social and environmental equity and the location of the County’s low-income housing and business sectors within the 100-year floodplain and even delineated floodways.
Continue local education, particularly with rafting and fishing guides regarding the natural history of the Hoh River and critical function logjams play in the river’s morphology and
ecology. Education can also include discussions of public safety and hazards in natural waterways.
Sustain the Resiliency Plan leadership team as a forum of communication and means of periodically updating the Plan. Ensure that all governmental entity considering a study or action
within the valley communicate with the leadership team.
Full and Partial Acquisitions and Relocation Actions
The most effective long-term flood protection is to remove structures from flood hazard areas, which also facilitates habitat restoration of these ecologically valuable areas. To do
this the property can be acquired or there are additional options such as fee simple acquisitions, conservation easements, life estates and relocation. Relocation grants allow the landowner
to move to a safer property in the area while ownership of the flood-prone property is transferred to a government, other public entity, land trust or NGO. Portions of the Upper Hoh
Road are prime candidates for relocation to eliminate conflicts with the river that result in frequent washouts and pose risks to the public and ecosystem. Likewise, landowners on the
south side of the river, losing land and structures to the river, would benefit from similar relocation options. Addressing these conflicts is critical to providing future resiliency
in the Middle Hoh.
Reaches of the Middle Hoh that are currently in conservation or owned by local, state or federal entities provide the greatest opportunities to improve ecologic resiliency by protecting
existing mature forests and high-quality floodplain habitats. Significant progress has already been made to create a protected corridor along the Middle Hoh River, including most of
the Willoughby Creek, Morgan’s Crossing and Spruce Canyon Reaches. Private ownership along the river corridor is centered around the Lindner Creek area in the Morgan’s Crossing Reach
and the south of the river in the Huelsdonk-South Fork Reach (plus the Lewis Homestead). Habitat protection and restoration in these areas should be pursued with interested landowners
through outreach and collaboration, where high-quality habitat currently exists.
Restoration actions in the Middle Hoh to create a multi-thread main stem channel with vegetated islands, maintained by stable instream wood and connection with off-channel floodplain
habitat, will have the greatest ecological benefit by directly addressing limiting factors contributing to the decline of salmon in the Hoh, and providing channel and habitat resiliency
into the future. There is historical evidence and local analogs that demonstrate the rivers planform has been altered, resulting in a single thread wandering channel that has significantly
more energy than the individual channel threads of the historic anastomosing or multi-thread river. This higher energy, coupled with logging of the riparian corridor removing the large
trees that once lined the channel banks, has resulted in high channel migration rates, frequent channel avulsions and immature floodplain forests, unable to withstand the river’s erosive
forces. The greatest risk to salmon survival in the Middle Hoh is loss of high-quality rearing habitat found in floodplain side channels, wetlands and beaver ponds. Protection and restoration
of these habitats is key to the long-term resiliency of the species and the broader ecosystem as a whole. Development of a mature riparian corridor, with large conifers capable of acting
as key pieces in the channel will form stable instream habitat complexity and limit further erosion into the bank. Invasive plant prevention and control, planting and other targeted
silvicultural actions that can be taken to accelerate the natural succession of the riparian forest will ultimately provide the long-term resiliency needed to enable Hoh River salmon
to persist into the future.
Instream & Floodplain Restoration
Riparian Restoration
Restoration of a mature riparian corridor with large conifers capable of acting as key pieces (remaining stable) in the river is critical to restoring long-term sustainable salmon habitat.
Given projected climate changes to snowpack, precipitation, flows and fire susceptibility, it is even more clear the focus of restoration actions should be restoring a mature conifer
and deciduous riparian forest throughout the Middle Hoh River. The riparian forest will play an even more critical role in both water temperature amelioration in floodplain side channel
networks and in the production of the large mature floodplain conifers–keystones in the generation of stable forested islands, side channels, floodplains and aquatic salmon habitat.
Although large trees are recruited and transported downstream from intact ONP riparian forest, 20th century logging of the majority of the Middle Hoh River’s forests has decreased the
overall resiliency of the river’s aquatic and riparian ecosystems by increasing the prevalence of red alder and willows on the floodplain. Projects to facilitate and support the regrowth
of mature conifer forests wherever feasible is necessary to improving the overall resiliency of the Middle Hoh River. The future Middle Hoh River aquatic and riparian ecosystem without
riparian forest restoration of floodplain conifers will simply be less resilient over the next few centuries than a restored riparian and floodplain forest. Restoring the mature coniferous
component to the Hoh River floodplains is the mid- and long-term solution to regenerating the resiliency of the entire riverine landscape, with constructed ELJs as the short-term surrogate
for the large trees needed.
Conifer Release
Understory conifers will be released by cutting adjacent overstory deciduous trees to provide a minimum of 40% full sunlight, promoting faster growth (Emmingham et al 2000). Locations
are limited to where young conifers (less than 6-ft tall), are established and growing on the floodplain. Any trees downed should be left on the floodplain or otherwise utilized for
restoration actions, like yarding into an adjacent side channel if permitted. If the conifer seedling is small, the understory vegetation may also require scheduled understory brushing
to maintain sunlight exposure until it is sufficiently tall.
Thinning and Planting
Where conifers are not currently established on the floodplains planting is needed to accelerate forest succession. In preparation of planting seedlings, overstory red alder will first
be cleared forming a 30-ft diameter circle gap that is planted Sitka spruce and red cedar, with cottonwood as well where likely to succeed (Figure 3). Cleared red alder is stacked,
forming a circle around the planted seedlings to deter elk browsing. And
similar to conifer release of existing seedlings, any understory vegetation will require scheduled clearing for up to four or five years until planted seedlings achieve a sufficient
height to not be obstructed by the understory.
Invasive Plant Prevention and Control
Invasive Plant Prevention and Control (ISPC) is a necessary action to maintain watershed resiliency, and in the world today with humans moving from one continent to another bringing
plants and seeds with them, it will be necessary as an ongoing watershed stewardship component far into the future. Native plant communities provide passive restoration inputs to the
river corridor that are degraded or replaced when invasives are allowed to spread. Significant efforts beginning with knotweeds in 2001 and continuing to the present are now focused
on Scotch broom, reed canarygrass, herb Robert, Canada thistle, tansy ragwort, and a recently introduced species - spotted jewelweed.
Planning is essential in order to treat existing invasives or to prevent movement of existing invasives or introduction of new species during project implementation. Invasive plant
propagules (seeds, rhizomes, and stem fragments able to grow into a new plant) are present both within and outside the watershed. Propagules are transported by wind, water, vehicles,
mowers, people and livestock and wildlife, infested equipment and materials used in construction, restoration, and in landscaping, gravel, nursery materials, and yard waste.
Each of these non-native and invasive species, left to spread, will reverse restoration and resiliency investments, will affect the health and resiliency of native forests necessary
for habitat maintenance, and require exponentially higher expenditures to control in future project implementation. When gravel for a forest road or fish passage project is sourced
from a mine once filled with Scotch broom or knotweed, seeds and fragments of these species will be brought in and establish at locations that were likely free of them, rapidly altering
and eliminating important habitats and ecosystem services ranging from carbon storage to air and water temperature attenuation. Invasive species are relatively easy to prevent, but
extremely difficult to eliminate once established, when the cost of eliminating these species grows, and associated environmental impacts continue to spread.
Actions to prevent the reversal of $1M invested in the past two decades since 2001 are:
A minimum of ten trained restoration technicians are required over eleven months each year to search 4,500 acres of seasonally changing river corridor, bars, floodplains and side channels
in the Middle and Lower Hoh River, and to apply prevention and control actions as described in the Resiliency Plan and at 10,000 Years Institute’s website (www.10000yearsinstitute.org/invasives).
In addition to continuing the years of annual work on the river, several additional actions are critical components to avoiding and preventing invasive species introductions and transport
to new locations, or to locations that have been previously treated multiple times over the past two decades (10KYI reports and maps at www.10000yearsinstitute.org/hrr).
In order to integrate invasives into projects and activities that can introduce or spread them, take the action necessary to understand what has occurred in the area of proposed project
construction in the past and by whom, whether a landowner or land manager or non-profit organization. Also, important to understand is that knowing that a particular species has been
reported or treated at one time at a site in a river reach or corridor is insufficient to predict what has arrived from outside sources, vectors, or pathways before or since, and how
many propagules may be present in soil at the site.
Early in project planning, establish relations and communicate with the entities involved in project area prevention and control. Establish a process to remain updated throughout each
year. This information, if integrated effectively, will protect previous investments and improve project outcomes.
Prior to the start of construction of any project, project partners would provide information about species present, history of treatments, and invasive plant surveys and treatments
would be initiated; ideally by the partner having the most expertise on the site and with the species.
Once all the invasives are known and integrated, incorporate measures to prevent, control, and mitigate them by establishing equipment that stays on site and is washed in a fully contained
and monitored location prior to leaving the site.
Shapefiles, maps, geodatabases, survey and treatment protocols, and staff to provide site visits and past reports for work conducted from the ONP boundary to the Pacific Ocean on all
public, tribal, conservation, and most private lands in the watershed are available at 10,000 Years Institute upon request.
Engineered Log Jams and Large Wood Placement
Engineered log jams (ELJs) are intended to mimic natural logjams and restore the geomorphic functions of natural log jams by increasing flow resistance and slowing flow velocities, splitting
flow into multiple channels, forcing main stem channel pools, and connecting the channel to side channels and the adjacent floodplain (Abbe and Montgomery, 2003; Montgomery et al.,
2003). Typical ELJs can be 10-20 ft in height and 40 to over 100 ft wide. The dimensions of the old growth trees once found in the valley included rootwads well over 30 ft in diameter,
stems 15-20 ft in diameter and lengths of over 200 ft. Thus, a single old growth tree is larger than most ELJs, each of which is intended to replace the functions of the massive trees
that once fell into the river. Log jams provide critical habitat functions such as triggering and sustaining the formation of deep pools, retaining spawning gravels, and providing
in-stream cover. The goal of implementing engineered log jams is to re-initiate these habitat-forming processes in the near-term until natural wood recruitment from the restored riparian
forest sustains those processes in the long-term.
Design and placement of ELJs and smaller instream wood placements need to both meet geomorphic and habitat objectives while not increasing flooding or erosion hazard risks to adjacent
landowners, public river users and fitting in with the floodplain management of the river system. Through the project reach, the Middle Hoh is categorized as a Special Flood Hazard
Area with a regulatory Zone A floodplain by the National Flood Insurance Program (NFIP). Jefferson County code, Section 15.15.080, describes the limitations to development (referred
to as encroachments) within regulatory floodplains with base flood elevations but no floodways and requires that the proposed encroachment would “not result increase the water surface
elevation of the base flood more than one foot at any point within the community” (Section 15.15.080(3)).
Floodplain regulations require that a hydrologic and hydraulic analysis be conducted on the proposed project actions to assess if the water surface elevations during a 100-year flood
event (referred to as the Base Flood Elevation) would be increased a foot or more as a result of the proposed actions. If proposed restoration actions are shown to increase the Base
Flood Elevation (BFE) in the project reach one foot or more, a Conditional Letter of Map Revision (CLOMR) would need to be obtained from FEMA to document the proposed changes to the
BFE and the 100-year floodplain before the project actions could be implemented. In addition, no increase in BFEs can impact an insurable structure as defined by the NFIP. Once the
project is completed, a Letter of Map Revision (LOMR) would need to be reviewed and approved by FEMA. The time frame for receiving a CLOMR and LOMR can be on the order of 6-12 months
and 3-6 months, respectively, and thereby can significantly increase the design timeline for restoration actions. The floodplain management regulations, as well as the feasibility of
pursuing the CLOMR/LOMR pathway, will need to be factored into the prioritization and design development of restoration actions in the project reaches.
Apex Engineered Log Jams
Apex ELJs are intended to mimic natural logjams that create hardpoints or islands in the active river channel. This creates the same geomorphic functions of natural bar apex log jams:
deep pools, improved hyporheic (groundwater) exchange, forested islands, complex aquatic cover, shade and new secondary channels. These structures are critical in creating and sustaining
secondary channels and floodplain side channels that create essential salmonid habitat that is more shaded and stable than the main river channel. Within the active migration zone of
the Middle Hoh the river is likely to re-occupy the same location every 25-35 years. Arrays of bar apex jams are effective at protecting floodplain and side channels that are otherwise
at risk of erosion by migration of the main channel. Apex ELJs are intended to split flow around the structures creating a stabilize bar and/or floodplain surface in the lee and partitioning
stream power into two channels instead of one to reduce channel migration rates and increase channel length. The structures are designed to mimic hardpoints in the channel that will
stabilize sediment in the lee to reduce hydraulic forces, allowing vegetation to establish and flourish and leading to forested islands over time that can provide a long-term source
of large wood to the river. Because the structures are often placed in areas with high hydraulic forces, deep pools are often scoured at the front face and around the corners of the
jam. Apex ELJs can be built in the middle of the river, but it is much less costly and lower impact to build them into existing gravel bars or floodplain areas where the main channel
is likely to migrate. Consequently, apex ELJs are constructed as a group of multiple structures across a migration zone to protect floodplain side channel complexes, as well as local
infrastructure, businesses, and homes. Within these arrays the apex ELJs work together prevent the mainstem channel from cutting the treatment area while allowing, even encouraging,
numerous side channels to flow through the same area. This strategy has been used very successfully to restore habitat and protect communities in large rivers across the state such
as the Upper Quinault, Elwha, South Fork Nooksack, Satsop, Wynoochee, Cowlitz, Entiat, Walla Walla.
Deflector Engineered Log Jams
Deflector ELJs, which include log jams installed adjacent to the channel margin, are intended to mimic the geomorphic functions of natural flow deflection from meander bend log jams.
The structures are primarily constructed along a bank and, as their name states, are intended to deflect flow from one area of the river corridor to another. Deflector ELJs can be used
to slow channel migration rates to historical levels on a particular portion of bank by deflecting flow away from the bank, as well as increase the frequency of side channel inundation
by deflecting flow towards side channel inlets. Because they are often placed in areas with high hydraulic forces (such as the outside of an actively migrating meander bend), large
scour pools develop at the head of the structures which can provide important holding habitat for salmon. Deflector ELJs can also be used to protect developing riparian vegetation located
behind the structures by reducing the rates of future channel migration and erosion. The structures can be placed in groups to treat larger areas such as the entirety of a meander bend.
Key Piece Placement or Small Engineered Logjams
The placement of Key-sized logs and smaller “side channel’ ELJs is intended to improve existing habitat conditions within less hydraulically active sections of the floodplain to improve
local habitat conditions and increase stable wood loading within the reach. These structures are suitable for locations where hydraulic forces (velocity and shear stress) are lower
than the main channel and construction access is limited. Placement of these smaller structures is designed to add hydraulic roughness and complexity to side channels and the floodplain,
provide pools with cover and rack mobilized small woody debris during floods. Natural snags that are deposited in the river should be protected from cutting and could be used to construct
and/or augment smaller ELJs. Smaller beaver dam analog structures, sited in areas of low velocity, could also provide additional habitat complexity thought the floodplains to further
enhance salmon rearing opportunities.
Opportunities to Support Middle Hoh River Resiliency
The opportunities presented here are a high-level assessment and may not capture all potential locations or opportunities for protection and/or restoration. More detailed conceptual
design development is needed to tailor the overarching approach to restoration to a specific location that considers local constraints and priorities.
Huelsdonk-South Fork Reach
Private property in the Huelsdonk-South Fork Reach south of the river at the Brandeberry and Rain Forest Road area (RM 29 – 30) and Fletcher Ranch are at the greatest short-term risk
of erosion and flooding and should be prioritized for facilitating conservation, acquisition and/or relocation actions to limit landowner risk and enable habitat restoration work (Figure
4). Continued outreach to other private landowners in the reach to similarly improve community and ecologic resiliency would be the next highest priority because these parcels are still
at risk of erosion and flooding. Numerous individual acquisitions from willing sellers, or full neighborhood relocation, would provide the greatest degree of certainty for landowners
planning for the future and while also allowing for significant aquatic habitat enhancement actions in a section of the river currently largely devoid of habitat complexity. Restoration
actions such as construction of ELJs, riparian planting and thinning, side channel wood loading and strategic excavations to improve side channel connectivity could be enacted aggressively
if flood and erosion risk to the landowners was eliminated through acquisition. Smaller-scale actions such as shoreline setbacks, installing wood along eroding banks and riparian planting
could be interim actions accomplished with cooperative agreements or conservation easements, and such actions can build community support for similar projects. However, property acquisition
from willing landowners is the long-term most beneficial action to restore the river’s resiliency corridor and aquatic habitats in the Huelsdonk-South Fork Reach.
The Upper Hoh Road in the Huelsdonk-South Fork Reach has a history of washouts, relocation and bank armoring from the Lewis Homestead upstream to ONP. The road encroaches into the delineated
resiliency corridor here where it disconnects aquatic habitat and is at risk of future washouts. The broad floodplain of the Middle Hoh through the Huelsdonk-South Fork Reach historically
was characterized by a multi-thread channel with large, vegetated islands complete with adjacent floodplains and abundant side channels and low-lying areas holding water throughout
the year. This framework was held together by mature large trees falling into the river as the channel migrated, slowing erosion, and providing instream habitat. The loss of these large
trees has resulted in a rapidly migrating channel that recycles through the floodplain faster than the trees can grow to sufficient size to provide key functions and remain stable (Figure
5). Opportunities exist to install clusters of apex ELJs to split flows, coupled with deflector ELJs to slow the channel migration rate along the channel margins to allow the forest
to mature. Planting conifers, strategic thinning, and invasive plant prevention and control in the lee of constructed ELJs and the adjacent floodplains will accelerate natural succession
of the riparian forest to create larger trees sooner, ultimately providing a local long-term source of large wood to the reach.
Additional small ELJs along floodplain side channel would further enhance off-channel habitat complexity. Implementation of such projects will require working closely with local landowners,
the Hoh Tribe and various agencies involved in permitting as any proposed actions will either be located on private lands or will impact private property somewhere in the reach. Ideally
acquisitions occur or conservation easements are established where restoration actions are proposed and where they will impact hydraulic conditions prior to their design and construction.
Opportunities to improve resiliency by protecting the Upper Hoh Road within the Huelsdonk-South Fork Reach using ELJs was not included here as relocation outside of the resiliency corridor
is the preferred option.
Spruce Canyon Reach
Short of the few parcels under private ownership at the confluence with Maple Creek, the Spruce Canyon Reach is currently in conservation or government owned. Opportunities exist to
engage the private landowners at Maple Creek for acquisition or conservation within the resiliency corridor, and establishing MOU’s with WDFW to ensure policies are consistent with
establishing and improving ecologic and community resiliency in the Middle Hoh.
As the Middle Hoh is confined through much of the Spruce Canyon Reach, there are limited opportunities for instream and floodplain restoration actions as hydraulic forces limit appropriate
locations for instream ELJs and the floodplain is relatively narrow. Local improvements to the riparian corridor include planting conifers, strategic thinning, and invasive plant prevention
and control on the adjacent floodplains where present would accelerate natural succession of the riparian forest to create larger trees sooner, ultimately providing a local long-term
source of large wood to the reach. Most of these areas are at the upstream end of the reach in the Spruce Island and Maple Creek confluence area north of the river where floodplains
exist. Recent erosion of Spruce Island has contributed more than 100 mature Sitka spruce to the channel since 2011. As most of the property is under conservation or owned by the government,
restoration actions can more readily be implemented as long as proposed actions fit within existing agreements.
Morgan’s Crossing Reach
Commercial and residential private property lies within the resiliency corridor, creating opportunities for conservation easements, acquisitions and relocation of infrastructure. These
areas are at risk from flooding and erosion and should be prioritized to facilitate restoration actions in the reach. Infrastructure at highest short-term risk includes the Jefferson
County Public Works facilities and east adjacent private property and structures south of the Upper Hoh Road, as recent channel migration increasing the potential for a partial to complete
channel avulsion through the existing side channel that flows just south of the facilities and buildings. Long-term plans for the Public Works facilities should be developed as they
are currently located within the resiliency corridor and are at high risk from flooding and erosion that will intensify over time. Continued outreach to other
private landowners in the reach to similarly improve community and ecologic resiliency would be the next highest priority, because parcels remain within the resiliency corridor that
will remain at risk of erosion and flooding. Full acquisition from willing sellers of these parcels would allow for significant aquatic habitat enhancement actions by opening up a
large area of the floodplain to natural processes. Restoration actions such as construction of ELJs, riparian planting and thinning, side channel wood loading and strategic excavations
to improve side channel connectivity could be enacted aggressively if flood and erosion risk to the landowners were eliminated through acquisition. Invasive plant prevention and control
has been conducted since 2001 and continues each year to support native understory and tree growth. Smaller-scale actions such as riparian enhancements, installing wood alongside channels
and planting open areas could be interim actions accomplished with landowner agreements or conservation easements, and such actions can build community support for similar and/or larger
projects (Figure 6). However, property acquisition from willing landowners is the most beneficial, long-term action to restore the river’s resiliency corridor and aquatic habitats in
the Morgan’s Crossing Reach.
The Upper Hoh Road encroaches into the resiliency corridor from RM 21 to 22.3, significantly limiting natural processes and salmon habitat quantity, quality, and availability north of
the road. Relocation of this section of the road from the floodplain would provide additional off-channel habitat for rearing salmon. Despite the consideration of various scenarios
over many years, no viable large-scale alternate route for the Upper Hoh Road has been identified to date due to land ownership, geologic, topographic, listed species constraints and
the costs for implementation. Potential setbacks of shorter segments are also met with many of these same challenges. An alternative visitor, economic and transportation paradigm may
eventually be needed to address the continuing risk of road closures and extensive, cumulative habitat impacts despite past and current mitigation efforts.
As the Middle Hoh exits Spruce Canyon the valley widens and the channel again begins to freely migrate across the floodplain, similar to the Huelsdonk-South Fork Reach. Opportunities
exist to install clusters of apex ELJs to split flows, coupled with deflector ELJs to slow the channel migration rate along the channel margins to allow the forest to mature (Figure
7). Planting conifers, strategic thinning, and invasive plant prevention and control in the lee of constructed ELJs and the adjacent floodplains will accelerate natural succession of
the riparian forest to create larger trees
sooner, ultimately providing a local long-term source of large wood to the reach. Implementation of such projects downstream of RM 23 will require working closely with local landowners,
the Hoh Tribe, river users and various agencies involved in permitting as most proposed actions will either be located on private lands or will impact private property somewhere in
the reach. Ideally, fee simple acquisitions or conservation easements occur where restoration actions are proposed and where they will impact hydraulic conditions prior to their design
and construction. Upstream of RM 23 most of the resiliency corridor is within conservation or government ownership, easing implementation and design costs and complexity. Opportunities
to improve resiliency by protecting the Upper Hoh Road within the Morgan’s Crossing Reach using ELJs was not included here, as relocation outside of the resiliency corridor is the preferred
option.
Willoughby Creek Reach
There remain a few private parcels within the resiliency corridor in the Willoughby Creek Reach, in the Elk Creek Floodplain south of the river between RM 18 and 19. The rest of the
resiliency corridor is in conservation or government owned. Opportunities exist to engage the private landowners for acquisition or conservation within the resiliency corridor.
The Middle Hoh retains its broad valley and floodplain as it enters the Willoughby Creek Reach, maintaining opportunities for clusters of apex ELJs to split flows coupled with deflector
ELJs on the adjacent floodplains slowing further channel migration. Side channels traversing floodplains with young forests include smaller ELJs to improve off-channel cover and habitat
complexity. Hydraulic conditions are less intense in this reach due to backwatering effects from Oxbow Canyon during large floods and may require less engineered approaches relative
to other reaches in the Middle Hoh. However, the same backwater effect promotes aggradation and Scotch broom establishment as velocities diminish approaching the canyon, creating a
dynamic channel that is prone to frequent avulsions. Planting conifers, strategic thinning, and invasive plant prevention and control in the lee of constructed ELJs and the adjacent
floodplains will accelerate natural succession of the riparian forest to create larger trees sooner, ultimately providing a local long-term source of large wood to the reach (Figure
8). Patches of remaining old-growth should be prioritized for protection from channel migration to maintain this largely lost floodplain habitat in the Middle Hoh. Most restoration
work in the reach would be on land under conservation or government ownership, making design and implementation relatively cheaper and simpler. If proposed restoration actions will
impact private land in the reach additional outreach and coordination is needed to move design and implementation forward. Ideally acquisitions occur or conservation easements are established
if needed prior to design and construction of restoration actions. Opportunities to improve resiliency by protecting the Upper Hoh Road within the Morgan’s Crossing Reach using ELJs
was not included here, as relocation outside of the resiliency corridor is the preferred option.
/
A project identified during the development of the Resiliency Plan for the lower end of the Willoughby Reach would restore flow to a disconnected side channel across a mature forested
floodplain on the south side (river left), across from the eroded reach of the Upper Hoh Road at MP 4.75, that directs river high flows at the eroded riverbank. Owned by a conservation
group and homestead landowners, the flow through the floodplain known locally as Peterson’s Bottom would relieve pressure on the Upper Hoh Road and provide 4,000 feet of high quality
and complex habitat passively restored to a spawning and rearing channel. The channel has been blocked and disconnected from the river by a large log jam formed when the river eroded
a stand of 125-175 years old red alder that remained as the original log jam along the scoured bank. The log jam continued building over the past 15 years and is now further anchored
by red alder and young Sitka spruce.
The restored channel would provide several benefits. It would, 1) split the channel and reduce flow along the damaged river and road bank opposite along the Upper Hoh Road, 2) restore
flowthrough mature forest for over 4,000 ft of historic spawning and rearing habitat, and 3) allow construction to progress on the Upper Hoh Road downstream of MP 4.25 with reduced
flow, and 4) reduce flow along the road and bank protection project, facilitate restoration of a functioning riparian zone, and hide the dolosse from view.
Oxbow Canyon Reach
Similar to the Spruce Canyon Reach, the Oxbow Canyon Reach is largely within conservation or government owned. However, the property essentially surrounded by the river and canyon is
privately owned and located within the resiliency corridor. These parcels are an opportunity to engage the private landowner for acquisition or other approach to conservation, and to
help establish a mature forest.
The Middle Hoh River is confined through the Oxbow Canyon Reach and there are limited opportunities for instream and floodplain restoration actions as hydraulic forces limit appropriate
locations for instream ELJs and the floodplain is relatively narrow (Figure 9). Local improvements to the riparian corridor could be achieved by planting conifers, strategic thinning,
and continued invasive plant prevention and control on the adjacent floodplains where they are present would accelerate natural succession of the riparian forest to create larger trees
sooner, ultimately providing a local long-term source of large wood to the reach. Most of the property is under conservation or owned by the government, therefore restoration actions
can more readily be implemented as long as proposed actions fit within existing agreements. In 2022, significant landslide activity contributing sediment to the channel, and drainage
from upslope logging activity is a concern.
/
Figure 9. Confined Oxbow Canyon reach with bedrock walls at RM 16.5, Oct. 2, 2020.
PRIORITIZATION & SEQUENCING
Prioritization Framework
A prioritization framework for habitat restoration was developed by applying a hierarchical implementation of restoration strategies (watershed scale process prioritization) adapted
from Roni et al. (2002) and Beechie et al. (2008), which results in the logical sequencing of restoration actions based on their probability of “success, response time, and longevity.”
Using this approach, we applied the following priority order to restoration opportunities in the five reaches of the study area:
Protect Hoh River floodplain and CMZ
Protect intact key habitats for Chinook, Coho, and steelhead, i.e., forested side channels
Restore mature forest riparian zones
Restore impaired processes
Enhance instream habitat
Using this framework, opportunities were scored by reach/location based on their ability to meet project goals and its related objectives for maximum improvement in aquatic habitat,
extent, and durability of anticipated biological benefits. Long-term and short-term actions were not considered separately as they can and should be evaluated and conducted in parallel
to make progress on longer-term goals like community engagement, conservation easements, and acquisition from willing sellers, while shorter-term actions are being planned, designed,
and implemented.
Higher scores and thus higher ranking were given to actions that provided protection of intact, naturally functioning habitat in a more expedient manner (e.g., through conservation easement
rather than through acquisition) and to actions which could provide improvement of a targeted impaired process and immediate improvements in aquatic habitat. A greater range of scores
was ascribed to the riparian restoration, ELJ and large wood placement criteria to account for the priority placed on actions which would address impaired processes identified in each
reach and the limiting factors for Hoh River salmon (i.e., lack of velocity refuges, spawning gravel sorting and storage, and floodplain connection/rearing habitat).
Table 1 presents the opportunity identified, and its score for the prioritization criteria considered based on improvements to community and ecologic resiliency. Overall community resiliency
is most improved upon relocation measures but have the least benefit from habitat restoration actions. Conversely ecologic resiliency is most improved through habitat restoration, preservation,
and conservation actions while community resiliency is less improved. Some actions, if continued unchanged, will diminish overall resiliency over time and should be avoided.
Scores for preservation and conservation measures assume that additional actions would be taken if needed to restore or maintain desired habitats. Opportunities for implementing riparian
and aquatic habitat restoration actions are constrained in the Huelsdonk-South Fork and Morgan’s Crossing Reaches due to large private inholdings within the resiliency corridor and
will require further landowner outreach and engagement. Working in these reaches in areas under conservation would still require agreements with private landowners effected by the project(s).
The Willoughby Creek Reach is similarly broad with abundant habitat potential, but more completely under conservation and has the added benefit of reduced flow velocities during large
floods due to the backwater effect of Oxbow Canyon. Acres of established Scotch broom in this reach developed on new and abandoned alluvial surfaces will add an additional level of
complexity to any on-ground restoration actions as ground disturbing activities will expose and potentially spread propagules within the site and/or beyond. Any restoration designs
developed will require coordination with project partners to ensure all invasive species concerns are addressed.
For these reasons, and the lack of restoration opportunities in Spruce and Oxbow Canyon reaches, we recommend prioritizing short-term habitat restoration actions in the Willoughby Creek
Reach and where there are willing landowners in the Huelsdonk-South Fork and Morgan’s Crossing Reaches, pursued concurrent with landowner outreach over the long-term to acquire properties
or property rights (conservation easements) or to facilitate relocation to safer ground in support of neighborhoods as well as habitat protection and restoration.
Priorities for relocation of infrastructure and landowners from hazard areas include the Upper Hoh Road, communities south of the river in the Huelsdonk-South Fork Reach, and the Jefferson
County Public Works facilities and east adjacent landowners. Pursuing relocation scores at the top overall for cumulative resiliency benefiting both the community and aquatic environment.
Table 2. Actions Identified and scored with respect to improving resiliency in the Middle Hoh (0=no resiliency benefit, 10=most resiliency benefit). Scoring is based on current conditions
and can change in the future depending on changing conditions and stakeholder priorities.
Proposed Actions
Community Resiliency
Ecologic Resiliency
Cumulative Resiliency
Preservation and Conservation
Conservation easements with willing landowners
6
5
11
Fee simple property acquisitions from willing sellers for conservation
5
8
13
Average
5.5
6.5
12
Relocation and Infrastructure Protection
Road relocation out of resiliency corridor
8
6
14
Relocate at risk landowners to safer areas
10
8
18
Habitat “friendly” erosion protection for existing development
5
5
8
Develop and implement county plan for new development in geologically safe areas outside of resiliency corridor
10
10
20
Improve visitor access through Middle Hoh to ONP*
8
0
8
Continue past practices to protect road
-5
-9
-14
Average
6
3
9
Habitat Restoration
Reach restoration proposals focused on floodplain side channels
3
10
13
Floodplain forestry to advance conifer growth
4
7
11
Restore and sustain forested islands
4
10
14
Invasive plant prevention and control
8
10
18
Restore and sustain mainstem pools and cover
0
10
10
Average
3.8
9.4
13.2
Cumulative Resiliency Score
Total possible
260
Total
144
Average
11.1
*visitor access could include improved local river access but this could impact ecological resiliency, it could also include reducing vehicular traffic which would improve ecologic
resiliency
Action Sequencing
The Plan advances a holistic approach to protecting and improving conditions for salmon, people and the unique ecosystem of one of the great, iconic rivers of the United States. Implementing
specific actions described in the Plan will involve various levels of planning. The resiliency corridor delineated in the Resiliency Plan provides a geographic template for conservation
and restoration and is central to this plan’s approach. Land within the resiliency corridor (Appendix D, Map 9) has an elevated risk of flooding and erosion which contributes to its
high ecological value and vulnerabilities. Simply put, it is an area for natural processes to dominate and aquatic species to thrive, but is unadvisable for human development due to
high and increasing costs and difficulty of defending against the river’s encroachments, or to mitigate its impacts. Thus, open space protections – in the form of conservation easements,
life estates, or fee simple acquisition from willing landowners within the resiliency corridor - will advance the overall resiliency plan’s objectives. Restoration actions require a
more intensive process of analysis and planning to ensure they will achieve the desired goals and not have adverse impacts. Restoration actions would also go through a thorough vetting
with stakeholders before being implemented.
CONCEPTUAL RESTORATION STRATEGY
Restoration actions will improve salmon recovery throughout most of the Middle Hoh valley. Three priority restoration reaches within the valley were prioritized based on current risks
to habitat and local communities. Restoration strategies begin with an understanding of current conditions that are limiting aquatic and riparian
habitat, how these conditions differ from an undisturbed condition, the reasons habitat has been degraded and what is needed for recovery. Conceptual designs are intended to convey the
general strategy and not the specific types and locations of restoration actions. The goal of concept designs is to restore the processes and habitats that will strengthen wild salmon
populations. The primary factor prolonging the natural recovery of the Middle Hoh River is a lack of large trees within the CMZ and bank armoring along the Upper Hoh Road. Large trees
are needed to form logjams which create islands, side channels and provide protected areas for patches of trees to mature. The proposed design approach taken has been to mimic the
role old-growth trees once provided in forcing channel planform and the formation and maintenance of salmon habitat using ELJs. The ELJs restore the large wood cycle that has been lost.
Arrays of ELJs protect large portions of forested floodplain from being reoccupied by the mainstem channel while forming and sustaining side channel networks. By protecting floodplain
areas on the margins of the CMZ, the ELJ arrays also protect developed areas. Floodplain side channels provide some of the most valuable salmonid habitat. Side channels are much more
stable than the main channel, they have more stable spawning gravels, excellent shade and rearing habitat. They also extend the length of cold-water tributaries entering the Hoh River
valley. This conceptual strategy has been successfully implemented across rivers of Washington State including the Upper Quinault and the Elwha valleys on the Olympic Peninsula.
Most of the floodplain forests within the Middle Hoh valley are in early successional stages so there are significant opportunities to implement forest restoration actions to accelerate
evolution into a mature riparian forest with abundant large conifers. Proposed actions including releasing individual conifers or clearing larger patches and seeding with conifer throughout
the floodplain forests. This would establish a more mixed conifer deciduous forest in lieu of the more common monotypic red alder stands. Historic and ongoing introduction and spread
of invasive species into and within the Middle Hoh has resulted in the widespread distribution of multiple invasive species across all reaches. Identifying, treating and monitoring
of invasive species present in project reaches, development of invasive species control plans for restoration actions that will disturb the ground or potentially introduce invasive
species, and long-term monitoring for invasive species all show success of plantings.
Working with the Steering Committee three valley reaches (five sites) were selected for developing conceptual restoration plans, including:
Lindner Complex Reach (RM 20.8-23.2)
Upper Lindner Complex Reach (RM 22.4-23.2)
Middle Lindner Complex Reach (RM 21.5-22.4)
Lower Lindner Complex Reach (RM 20.8-21.5)
Fletcher Ranch/TNC Reach (RM 27.3-28.3)
Brandeberry/Lewis Reach (RM 28.7-30.0)
For each site a description of the proposed actions is provided, including project constraints, implementation feasibility, and potential access and material staging areas.
These types of projects would engage the Hoh Tribe and state, federal and local agency stakeholders and local landowners throughout the analysis, alternatives design layouts, permitting,
preliminary and final designs and only be implemented with the support of all groups and funding. Targeted risk assessments may be needed to evaluate hazards and how risks change with
the proposed designs, such as but not limited to boater safety, slope stability adjacent to the river, channel migration threatening structures or private property, and temporary construction
impacts.
Lindner Complex Reach
The Lindner Complex Reach is located between RM 20.8 and 23.2, at the downstream end of the Morgan’s Crossing Reach, where the channel is currently flowing along the southern side of
the valley, leaving an extensive network of side channels flowing through the right bank (northern) floodplain (Figure 10). This floodplain spans approximately 160-acres (ac) and conveys
regular overbank floodwaters, with some side channels maintaining perennial flow. Historically, main stem channel threads have migrated and avulsed into the area over time, eroding
the floodplain and developing riparian forest. The main stem channel (or a significant channel thread) has not occupied the Lindner Creek Floodplain since the mid-1990’s, keeping primarily
to the south side of the valley. In recent years the main stem channel has been directed toward the Lindner Creek Floodplain, primarily due to an avulsion upstream around Morgan’s Island,
that moved the main stem channel away from the Upper Hoh Road (to the south) in the late 2000’s. Following this avulsion the main stem channel began to migrate into the upstream end
of Lindner Floodplain (near RM 23), increasing flow in the floodplain side channels as the main stem continued to migrate further into the side channel inlets. The increased flow in
these side channels is contributing to high quality and diverse habitat for rearing juvenile salmon, and is something to be protected along with a maturing forest of mixed age spruce
and red alder. While the higher side channel flow is beneficial to habitat formation, if left to increase unchecked it may ultimately lead to an avulsion of the main stem channel. Capture
of the main stem through the floodplain would rapidly erode the decades-old riparian forest, again resetting the clock and further prolonging the formation of a truly mature (greater
than 100-yrs) floodplain forest. The lack of forested side channel habitats, such as those found within the Lindner Creek Floodplain, is a limiting factor to salmon production in the
Middle Hoh River.
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Figure 10. The Lindner Complex Reach and boundaries of sub-reaches (RM 20.8-23.2).
The primary goal at the Lindner Complex Reach is to decrease channel migration rates sufficient to allow the floodplain to continue to develop into mature riparian forest with large
trees of sufficient size and number to provide self-sustaining salmon habitat. Protecting the floodplain from frequent erosion will provide the time
needed for the large trees to grow on the floodplains, and for rearing and spawning habitat to form, evolve and persist.
The aim is not to eliminate flow into the floodplain and side channel network, but rather meter the flow such that the high-quality habitat maintained by the current flow remains, but
the main stem channel is prevented from re-occupying the floodplain. The proposed approach is to construct an array of engineered logjams (ELJs) where the channel is actively migrating
northward to limit further erosion of the floodplain, spaced such that flow can enter the floodplain between ELJs but is too narrow for the main stem channel to migrate into the affected
area (Figure 11). Additional ELJs are proposed along the remaining banks of the forested floodplains, both with the channel and the less active elevated floodplain surfaces along the
floodplain margins. Where existing natural logjams exist in locations where ELJs would be proposed, an attempt will be made to stabilize the logjam to prolong its persistence on the
landscape. Smaller ELJs and wood placements are proposed along existing side channels throughout the Upper Lindner Floodplain to increase habitat complexity as well as provide resistance
to main stem channel avulsion (Figure 11). Creating openings in the riparian forest to accelerate conifer growth, planting conifer, and managing invasive species throughout the floodplains
will accelerate growth of the large trees needed for long-term stability. Apex ELJs in the active channel are proposed to split flow into multiple channels, further dissipating stream
energy while increasing hydraulic and habitat complexity (Figure 11).
Prior to implementing any project, a thorough analysis of existing conditions and proposed actions is necessary. Incorporating new findings, the project layout will evolve during the
next stage of design in order to best achieve the project goals and limit adverse impacts. These types of projects would engage stakeholders throughout the analysis, alternative layouts,
final design and only be implemented with the support of local landowners and regulatory agencies.
Upper Lindner Complex Sub-Reach Concept Design (RM 22.4-23.2)
The primary short-term goal of restoration at the Upper Lindner Complex Sub-Reach is to protect the main perennial side channel flowing along the northern margin of the Lindner Floodplain,
which is prime habitat for Chinook and Coho spawning and rearing habitat (Figure 11). There is a significant risk of the Hoh River migrating and or avulsing into the main side channel,
leading to the loss of important off-channel habitat and risks to the adjacent local community and Upper Hoh Road. The proposed project would sustain the main side channel, form new
side channels, while also lowering the chance of the mainstem Hoh River migrating northward toward the Lindner community and Upper Hoh Road.
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Figure 11. Conceptual restoration plan for the Upper Lindner Creek Floodplain (RM 22.4-23.2).
The restoration layout proposes to protect the Upper Lindner Floodplain from lateral erosion and/or avulsion from the main stem channel, to allow sufficient time for the riparian forest
to mature. Maintaining this floodplain habitat and allowing it to mature over time will provide valuable rearing and spawning habitat, off-channel refugia during floods, and connection
to hyporheic cool water to all life stages and species of salmon in the Middle Hoh. Once mature, the floodplain forest will provide and maintain these needed habitats and remain protected
from erosion once large conifers have been re-established of sufficient size to remain stable in the main stem channel.
Construction would likely occur with ground-based equipment utilizing temporary access routes to enter and navigate between proposed ELJs and wood placements within the site. Temporary
bridges will likely be required to span existing side channels within the floodplains. Proposed ELJs in the current active channel may require temporary diversion or bridging of main
stem channel threads to access sites, depending where flow is at the time of construction. All temporary access routes and bridges, clearing for ELJs and wood placement construction,
diversion of the channel or other disturbances will be minimized to the extent feasible and will be coordinated with all pertinent permit agencies, the Hoh Tribe, and landowners. Any
native vegetation cleared during construction will be incorporated into the project. Access into the site from the north would likely be from private property and ideally include 2
– 3 entrance points. Wash stations for equipment and other techniques will be used to limit invasive species introduction and spread along temporary access routes and staging areas.
Other alternatives such as helicopter delivery of wood to the site will be considered to minimize the disturbance and traffic associated with material haul trucks.
Temporary staging areas for sorting and stockpiling construction materials, equipment servicing and more would ideally be located on the south side of the Upper Hoh Road, to minimize
trips crossing this busy road. Large, flat cleared fields are ideal for temporary staging areas, there are several candidates on either side of the Upper Hoh Road adjacent to the project
reach. The need for a local temporary staging area and access to the site will require outreach and authorization from one or more landowners between the river and the Upper Hoh Road.
An existing logging road winds down from the Hoh Mainline, adjacent to a quarry next to Clear Creek, down to the side channel flowing to the south of Clear Creek Island (Figure 11).
This route could be extended a bit further downstream to access the left bank and floodplain downstream to Red Creek. Below Red Creek access is very limited as unstable high bluffs
line the left bank, preventing an access route from the south. Options to access the left bank include crossing the main stem channel or waiting for a bar to form that extends upstream
of Red Creek, providing ground access from this lower floodplain down to the active channel to the east.
The proposed restoration plan would have to be phased and implemented over several years. Sequencing of implementation should largely be dictated by the alignment of the main stem channel
immediately prior to construction, as working away from the main stem as much as possible reduces costs and potential temporary impacts to resources. In general, phasing work should
prioritize implementation on the side of the river opposite the main stem channel, and/or if appropriate locations where there is a more immediate need. Beginning treatment at the upstream
end of the reach will reduce the risk of the main channel moving up against the Upper Hoh Road and threatening the local community along the road.
Middle Lindner Complex Sub-Reach Concept Design (RM 21.5-22.4)
Proposed restoration actions in the Middle Lindner Complex Sub-Reach are very similar to those described upstream, however without the focus of limiting avulsion potential through the
Lindner Floodplain (Figure 12). The main Lindner Floodplain side channel does flow just south of the Jefferson Co Public Works Facilities, continuing downstream parallel to the Upper
Hoh Road, where bank armoring has occurred. Part of the proposed restoration at the Middle Lindner Complex Reach is the relocation of the Public Works facilities to a safer location
and restoration of the property back to a forested floodplain. Replacement with and/or covering of riprap with large wood structures is also included in the proposed concept design
to minimize the loss of habitat (Figure 12).
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Figure 12. Conceptual restoration plan for the Middle Lindner Creek Floodplain (RM 21.5-22.4).
The current position of the main stem channel, up against the geologically unstable southern valley margin, is not ideal as it is can be a major sediment contributor to the river if
the channel is actively eroding the hillside and initiating slope failure (Figure 12). The proposed design includes ELJs along the southern valley margin to establish a floodplain buffer
between the river and valley toe, likely requiring temporary channel diversions and crossings to implement as ground access from the south is not possible at this location.
Ground-based construction equipment would be used utilizing temporary access roads and bridges to access proposed construction sites. All clearing, water, and invasive plant management
needed to construct the project will be coordinated will all permit agencies, the Hoh Tribe, and landowners. Any native vegetation cleared during construction will be incorporated into
the project. Access into the site from the north would likely be from private property and ideally include 2 – 3 entrance points. Wash stations for equipment and other techniques will
be used to limit invasive species introduction and spread along temporary access routes and staging areas. Other alternatives such as helicopter delivery of wood to the site will be
considered to minimize the disturbance and traffic associated with material haul trucks.
Similar to the Upper Lindner Creek design, temporary staging would ideally occur south of the Upper Hoh Road to minimize crossing the busy road, ideally in a large, flat cleared field
adjacent to an access road entrance to the site. The need for a local temporary staging area and access to the site will require outreach and authorization from one or more landowners
between the river and the Upper Hoh Road.
The proposed restoration design would be phased over several construction seasons to fully complete likely. Sequencing of implementation should continue from Upper Linder floodplain
and progress downstream through the Middle Lindner Floodplain, to the extent possible.
Lower Lindner Complex Sub-Reach Concept Design (RM 20.8-21.5)
Proposed restoration actions in the Lower Lindner Complex Sub-Reach are very similar to those described upstream, without the limitation of the main stem channel up against the geologically
unstable southern valley wall (Figure 13). The lower end of the Lindner Floodplain includes the confluence with Lindner Creek to the north, and all side channels returning to the main
stem Hoh River and the downstream end. The northern margin of the Lindner Floodplain is lined with riprap for approximately 1000-ft at the downstream end of the floodplain (Figure 13).
Part of restoration designs at this site would include alternatives for improving habitat along this degraded margin. Opportunities exist to integrate with recently constructed dolo
ELJs by Federal Highways Administration in 2021.
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Figure 13. Conceptual restoration plan for the Lower Lindner Creek Floodplain (RM 20.8-21.5).
Construction would be completed with ground-based equipment accessing construction sites via temporary access roads and bridges. The southern side of the valley includes an established
floodplain at the lower end of the Lindner Floodplain, providing the opportunity for ground access from the south utilizing abandoned logging roads. While it may be possible to implement
this concept without a temporary crossing of the main stem channel, it is anticipated that multiple smaller crossings of side channels will be required as temporary roads traverse the
floodplains on either side of the river. Access into the site from the north would likely be from private property and ideally include 2 – 3 entrance points. Wash stations for equipment
and other techniques will be used to limit invasive species introduction and spread along temporary access routes and staging areas. Other alternatives such as helicopter delivery of
wood to the site will be considered to minimize the disturbance and traffic associated with material haul trucks. All clearing, water, and invasive plant management needed to construct
the project will be coordinated will all permit agencies, the Hoh Tribe, and landowners.
Fletcher Ranch/TNC Sub-Reach (RM 27.3-28.3)
The Middle Hoh River at RM 28 is very dynamic and prone to rapid channel migration and avulsions and is characterized by broad unvegetated gravel bars with abundant mobile wood. As the
channel migration rate has increased over time, the channel has grown wider and the floodplain forests are eroded faster than large trees can be replenished. The small trees comprising
much of the riparian forests are largely ineffective in limiting erosion, avulsions or providing persistent, diverse habitat. An example of the instability experienced in the project
reach due to a lack of mature riparian forests is the avulsion that started in 2016 between RM 27.8 – 28.3 on the south side of the channel. Leading up to 2016, the main stem channel
flowed in a large meander bend, in what is now an overflow flow channel, just upstream of Canyon Creek. On the inside of this meander bend was a network of side channels through the
left bank floodplain that supported rearing and spawning salmon. Flow in these side channels increased over time until 2016 when the main stem channel was captured and avulsed into
the side channels, cutting off the large meander and began rapidly expanding the side channels to accommodate the main stem channel. Expansion of the channel continues as there is a
lack of large trees of
sufficient number and size to impede further erosion, resulting in a loss of valuable side channel habitat and private property.
The proposed restoration layout works to both protect existing forested floodplain from lateral erosion and avulsions, as well as create new forested floodplain within the current active
channel. Where a forested floodplain currently exists ELJs are strategically placed along the vegetated margin with the active channel to deflect flow away from eroding banks and provide
sufficient time for the riparian forest to mature. The wide floodplain at the Canyon Creek confluence of the right bank is a good example where this strategy is proposed (Figure 14.)
to restore the eroded floodplain, utilizing an array of ELJs to dissipate the river’s energy before it impinges on the current channel banks. This approach is proposed on the left bank
where the channel avulsed in 2016 and has been widening ever since. Where existing natural logjams exist in proposed ELJ locations, an attempt will be made to stabilize the logjam to
prolong its persistence on the landscape. Smaller ELJs and wood placements are proposed along existing side channels throughout the forested floodplains to increase habitat complexity
as well as provide resistance to main stem channel avulsion (Figure 14). Creating openings in the riparian forest to accelerate conifer growth, planting conifer, and managing invasive
species throughout the floodplains will accelerate the production of the large trees needed for long-term channel stability. Apex ELJs in the active channel are proposed to split flow
into multiple channels, further dissipating stream energy while increasing hydraulic and habitat complexity and creating forested islands (Figure 14).
Ground-based construction techniques would be used to implement the proposed restoration designs, utilizing temporary access routes to enter and navigate between proposed ELJs and wood
placements within the site. Temporary bridges will likely be required to span existing side channels within the floodplains. Proposed ELJs in the current active channel may require
temporary diversion or bridging of main stem channel threads for access, depending on where flow is at the time of construction. All temporary access routes and bridges, clearing for
ELJs and wood placement construction, diversion of the channel or other disturbances will be minimized to the extent feasible. Any native vegetation cleared during construction will
be incorporated into the project. Access into the site from the north would likely be from TNC property and ideally include 2 – 3 entrance points. Depending on the location of the
main stem channel during construction, access may be possible from the Upper Hoh Road at the downstream end of the project reach where the road is adjacent to the river and begins to
climb up the hill. Another alternative site is at the upstream end of the project reach, coming down from the Upper Hoh Road onto the right bank floodplain just above the project reach
(Figure 14). Access from the south would need to be from private property, requiring outreach and authorization from one or more landowners. Wash stations for equipment and other techniques
will be used to limit invasive species introduction and spread along temporary access routes
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Figure 14. Conceptual restoration plan for the Fletcher Ranch/TNC Sub-Reach (RM 27.3-28.3).
Areas for temporary staging of construction materials and base for construction management would ideally be located on either side (north and south) of the river to eliminate the need
to cross the channel or make a long haul to deliver materials to the other side. Large, flat cleared fields are ideal for temporary staging areas, there are a few candidates on the
south side of the river adjacent to the project reach on private property. Using these fields would require outreach and authorization from one or more landowners. However, the main
stem channel is currently up against the left bank and would require crossing multiple channel threads to access proposed ELJ sites from the south, complicating access. There is not
an obvious location on the north side of the river that is close to the project reach suitable for a temporary staging area. All of the flat ground north of the project reach is TNC
land, is forested and would require clearing to be used for temporary staging. Additional work would need to be done to identify appropriate staging on the north side of the river,
working with TNC and adjacent landowners to find an appropriate site.
The proposed restoration plan would have to be phased and implemented over several years. Sequencing of implementation should largely be dictated by the alignment of the main stem channel
immediately prior to construction, as working away from the main stem as much as possible reduces costs and potential temporary impacts to resources. In general, phasing work should
prioritize implementation on the side of the river opposite the main stem channel, and/or if appropriate locations where there is a more immediate need.
Brandeberry/Lewis Sub-Reach (RM 28.7-30.0)
Similar to the Fletcher/TNC Sub-Reach, the Brandeberry/Lewis Sub-reach is very dynamic and characterized by broad unvegetated gravel bars with abundant mobile wood on the surface and
high channel migration rates. The active channel has continued to widen as the adjacent floodplain forests provide little resistance to lateral erosion. Active channel migration over
the last several decades has eroded large, forested floodplains on either side of the channel that once supported spawning and rearing salmon, and replaced them with broad barren gravel
bars. This process has occurred on the floodplain between the Brandeberry and Rain Forest Lots
communities on the south side of the river since the mid-2000’s, with more and more floodplain forest lost over time, homes lost to erosion and a number of others remaining at risk now
that the floodplain buffer between the communities and the river is gone.
The restoration design layout follows the same principles as the other concept design sites, protecting existing forested floodplain from erosion and avulsions, creating new floodplain
where the active channel is over-widened, and splitting main stem flows into multiple threads to partition shear stresses and reduce stream power. Where a forested floodplain currently
exists ELJs are strategically placed along the vegetated margin with the active channel to deflect flow away from eroding banks and provide sufficient time for the riparian forest to
mature. The wide floodplain on the right bank adjacent to the Lewis Homestead is a good example of this strategy being used (Figure 15). Where the active channel is active widening
the HMZ and is over-widened, ELJs are proposed to limit further widening and restore the previously eroded floodplain. This approach is proposed on the left bank, the focus of recent
main stem erosion and loss of extensive forested floodplains. Where existing natural logjams exist in locations where ELJs are proposed, an attempt will be made to stabilize the logjam
to prolong its persistence on the landscape. Smaller ELJs and wood placements are proposed along existing side channels throughout the forested floodplains to increase habitat complexity
as well as provide resistance to main stem channel avulsion (Figure 15). Creating openings in the riparian forest to accelerate conifer growth, planting conifer, and managing invasive
species throughout the floodplains and adjacent slopes where feasible, will accelerate growth of the large trees needed for long-term stability. Apex ELJs in the active channel are
proposed to split flow into multiple channels, further dissipating stream energy while increasing hydraulic and habitat complexity and creating initiation points for forested islands
to develop (Figure 15).
The construction approach would use ground-based construction methods to construct the proposed restoration designs, utilizing temporary access roads to enter and navigate through the
site building elements of the design. Temporary bridges will likely be required to span existing side channels within the floodplains. Proposed ELJs in the current active channel may
require temporary diversion or bridging of main stem channel threads to access, depending on where flow is at the time of construction. All temporary access routes and bridges, clearing
for ELJs and wood placement construction, diversion of the channel or other disturbances will be minimized to the extent feasible. Any native vegetation cleared during construction
will be incorporated into the project. Access from the south would be from private property within the Brandeberry and/or Rain Forest Lots communities, ideally including 2-3 entrance
points and requiring outreach and authorization from one or more landowners. Access from the south would be from DNR property on the downstream end of the project reach, or private
property on the upstream side, requiring outreach and authorization from the landowner.
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Figure 15. Conceptual restoration plan for the Brandeberry/Lewis Sub-Reach (RM 28.7-30.0).
Areas for temporary staging of construction materials and base for construction management would ideally be located on either side (north and south) of the river to eliminate the need
to cross the channel or make a long haul to deliver materials to the other side. Large, flat cleared fields are ideal for temporary staging areas, there are few possible sites on either
side of the channel that are close to the project reach. Using these fields would requiring outreach and authorization from one or more landowners. On the north side there are multiple
cleared fields on private property adjacent to the project reach and potential access points, however agreements with the landowner would be needed. On the south side of the river there
is a recent clear-cut off Brandeberry Road at the H-1000 intersection that could potentially be used for staging material that is on DNR land.
The proposed restoration plan would have to be phased and implemented over several years. Sequencing of implementation should largely be dictated by the alignment of the main stem channel
immediately prior to construction, as working away from the main stem as much as possible reduces costs and potential temporary impacts to resources. In general, phasing work should
prioritize implementation on the side of the river opposite the main stem channel, and/or if appropriate locations where there is a more immediate need.
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