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HomeMy WebLinkAboutEELGRASS REPORTGE0ENGINEER5 1 d 1101 South Fawcett Avenue, Suite 200 Tacoma, Washington 98403 253.383.4940 June 22, 2021 Washington Department of Fish and Wildlife 600 Capital Way North Olympia, Washington 98501 Attention: Mike Nicholas Subject: Eelgrass Delineation Point Whitney Access Redevelopment Jefferson County, Washington Project No. 3730-167-02 INTRODUCTION GeoEngineers, Inc. (GeoEngineers) was retained by Washington Department of Fish and Wildlife (WDFW) to perform an updated eelgrass delineation at the Point Whitney Access Site. WDFW is planning to widen the existing boat ramp by 2 feet and install 4 feet of ArmorFlex on either side. WDFW requested GeoEngineers conduct a new delineation because the previous delineation conducted by GeoEngineers in 2018 is over 3 years old and is no longer accepted under U.S. Army Corps of Engineers (Corps) eelgrass delineation guidance: Components of a Complete Eelgrass Delineation and Characterization Report (date January 9, 2018). This letter report documents the survey methods, and resulting extent and location of existing eelgrass beds found in the vicinity of the boat launch. Assessing and mitigating potential impacts to delineated eelgrass was not included as part of this scope. SCOPE AND METHODS The scope of work included conducting a Tier 1 eelgrass boundary survey surrounding the boat launch as the project is being designed to avoid impacts to eelgrass beds. GeoEngineers coordinated the site visit during low tides which allowed eelgrass within the project vicinity to be mapped through a combination of wading and snorkel survey techniques. The site visit was conducted on Monday, June 14, 2021 and completed in 1 day. Low tide occurred at 2:11 PM, at an elevation of -1.65 feet mean lower low water (MLLW) (Station 9445293 - Pleasant Harbor). Underwater visibility was estimated at approximately 7 feet prior to disturbing substrate. The survey team consisted of three GeoEngineers' scientists: Adam Wright and Emily Hurn completed the snorkel survey and Shawn Mahugh provided shore support. All three have extensive experience in shore - based eelgrass and macroalgae identification and delineation. Mapping was conducted with a Trimble GeoXH global positioning system (GPS) unit. Following differential correction post -processing, over 97 percent of points collected were reported to have between 5 and 15 centimeter (cm) accuracy. Washington Department of Fish and Wildlife June 22, 2021 Page 2 Eelgrass was primarily mapped by wading a single transect parallel to the waterline (Method 1), directly marking the eelgrass boundaries with the GPS ensemble. Points were collected every 5 to 15 feet as needed to capture the boundary geometry. A continuous bed of eelgrass was readily visible in less than 2 feet of water along much of the shoreline. Around the existing ramp the landward eelgrass boundary transitioned into deeper water. To complete the landward distribution of eelgrass mapping in this area one biologist snorkeled the eelgrass edge while a second swimmer remained at the surface with the GPS unit to mark the boundary (Method 2). The project was conducted following Corps guidelines described in Components of a Complete Eelgrass Delineation and Characterization Report (date January 9, 2018). A photographic record of the site has been included as Appendix A, Site Photographs. RESULTS SUMMARY A continuous native eelgrass (Zostera marina) bed was identified and mapped near the existing ramp (Figure 1, 2021 Eelgrass Map). Non-native eelgrass (Zostera japonica) was not encountered at the site. Based on WDFW provided bathymetry, the landward eelgrass bed boundary was mapped to occur at approximately -2 feet MLLW through the majority of the study area. At the ramp location, the bed transitioned to deeper water (approximately -6 feet MLLW) for roughly 25 feet along the beach. Eelgrass meeting the definition for a bed by either Method A or Method B (as defined in Corps guidance) was not observed landward of the mapped boundary shown on Figure 1. Eelgrass observed around the site was generally a continuous bed on either side of the ramp that transitioned to patches of eelgrass spaced less than 1 meter apart near the ramp location. Eelgrass point features collected by GPS were mapped using Geographic Information System (GIS) software (Figure 1). These features were interpreted into a line delineating the landward eelgrass bed boundary surrounding the ramp. The eelgrass bed extends beyond the mapped boundary laterally along the beach to the east and west. The waterward boundary was not mapped and appeared to extend beyond visibility limitations from the surface. Digital Shapefiles were provided with this report. Sargassum muticum was observed within and adjacent to the eelgrass bed and Desmarestia aculeata was observed shoreward of the eelgrass bed between approximately-2 and 0 feet MLLW. Substrate surrounding the eelgrass was predominantly gravel and sand with fine sediments. Beach substrate above the eelgrass bed quickly transitioned to gravels and cobbles at roughly 0 feet MLLW. LIMITATIONS We have prepared this revised letter report for WDFW. They may distribute copies of this status report to the their authorized agents and/or regulatory agencies as may be required. Within the limitations of scope, schedule and budget, our services have been executed in accordance with methods detailed within this report as prepared. The conclusions, recommendations, and opinions presented in this report are based on our professional knowledge, judgment and experience. No warranty, express or implied, applies to the services or this report. GEOENGINEERS I/�' File No, 3730-167-02 Washington Department of Fish and Wildlife June 22, 2021 We thank you for the opportunity to work with you on this project. If you have any questions regarding this letter report please contact Joe Callaghan at 253.383.4940. Sincerely, GeoEngineers, Inc. uW Emily R. Hum Biologist Shawn M. Mahugh, PWS Senior Biologist ERH:ALW:SMM:JOC:tlm Attachment: Figure 1.2021 Eelgrass Map Appendix A. Site Photographs fib Adam L. Wright, PWS Biologist Joseph 0. Callaghan, MS, PWS Principal Fisheries Biologist Disclaimer: Any electronic form, facsimile orhard copyofthe original document (email, text, table, and/orfigure), if provided, and any attachments are onlya copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record. Copyright© 2021 by GeoEngineers, Inc. All rights reserved. GEOENGINEER5 I�JI t 4 • err-: '� i 'bL .. ' _$� f '-1A Legend - Delineated Eelgrass Boundary o Boundary Points Eelgrass Existing Ramp ® Proposed Ramp Expansion Notes: 1. The locations of all features shown are approximate. 2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication. Data Source: Aerial from GoogleEarthPro 2017; 2005 WDFW topographic survey. Projection: NAD 1983 StatePlane Washington North FPS 4601 Feet 16 18 Eelgrass extends offsite Point ID I N Latitude W Longitude 1 47.762253-122.851467 2 47.762245-122.851422 3 47.762238-122.851357 4 47.762236-122.85131 5 47.762228-122.851273 6 47.762242-122.851232 7 47.76227-122.851233 8 47.762297-122.851216 9 47.762299-122.851187 10 47.762279-122.851142 11 47.762269-122.851161 12 47.762224-122.951162 13 47.762213-122.851154 14 47.7622-122.85113 15 47.762185-122.85111 16 47.762166-122,85108 17 47,762166-122,851046 18 47.762153 -122,851007 ~ 19 47.762142-122.850969 2021 Eelgrass Map Point Whitney Eelgrass Delineation Jefferson County, Washington GEOENGINEERS� Figure 1 APPENDIX A Site Photographs Photograph 1. Existing boat ramp lookingsnuth. Site Photographs Point Whitney Eelgrass Delineation Jefferson County, Washington GEOENGINEERS �2 Figure AA Approx. shoreward limit of eelgrass (Zostera marina) ' .---------------. ---••-•---•----------------- --- --•------- _... .sarc+assl �i,�, murrn Photograph I Site c4:mdi lojisNYest of ramp during approximately-1.65 fwt MLBV law title. Photograph 4. Eelgrass (Zosteramarw)and substrate. An Site Photographs Point Whitney Eelgrass Delineation Jefferson County, Washington GEOENGINEERS r FigureA-2 Photograph 5. Shoreline looking west from end existing boat ramp. Photograph 6. Shoreline looking east from end existing boat ramp. Site Photographs Point Whitney Eelgrass Delineation Jefferson County, Washington GEOENGINEERS� FigureA-3