HomeMy WebLinkAboutSEPA Att B2 Eelgrass Reverification 2018
146 N Canal St, Suite 111 Seattle, WA 98103 www.confenv.com
To: Anna Bausher, Jefferson County Department of Community Development
cc: Rick Mraz, Washington State Department of Ecology; Brad Nelson, BDN Inc.
From: Grant Novak, Confluence Environmental Company
Date: July 9, 2018
Re: BDN Inc. - Proposed Smersh Geoduck Farm: 2018 Zostera marina bed edge re-verification
This memo summarizes the findings of surveys conducted by Confluence Environmental Company
(Confluence) to re‐verify the location of the landward edge of the native eelgrass (Zostera marina)
bed on Jefferson County parcel 721031007 (Smersh parcel). The bed edge was previously surveyed in
2016 by Confluence. Representatives of the U.S. Corps of Engineers (Matthew Bennett, Pamela
Sanguinetti, and Deborah Schaeffer) visited the Smersh parcel on July 21, 2016 to confirm the
findings of the 2016 eelgrass delineation. The Corps was in agreement with the methods and agreed
that the boundaries of the dense and patchy eelgrass beds were appropriately mapped at that time.
Because more than one year has lapsed since the previous survey was completed, the Washington
State Department of Ecology and Jefferson County have requested that the bed edge be re‐verified to
ensure the proposed geoduck aquaculture project will be sighted at least 16 feet from native eelgrass
so as to reduce the potential for negative impacts to protected resources.
A biologist knowledgeable in Pacific Northwest seagrass identification and survey methods visited
the Smersh parcel during low tide on June 28th between 11:00 am and 1:00 pm. During the time of the
survey, water elevations ranged from ‐0.3 feet to ‐1.6 feet relative to mean lower low water (MLLW).
The surveyor crisscrossed the entirety of the parcel while scanning the substrate to the left and right
in an effort to locate and identify any submerged aquatic vegetation at the site, with a specific focus
on locating native eelgrass.
As with previous surveys, very small, sparse patches of non‐native Japanese eelgrass
(Zostera japonica) were found widely distributed between approximately +2 feet and ‐1 foot MLLW.
No native eelgrass was found above ‐1 foot MLLW. A dense bed of native eelgrass with a patchy
margin was observed below approximately ‐1 to ‐2 feet MLLW. The location of the landward edge of
the native eelgrass bed was accurately recorded using a differential GPS with sub‐meter accuracy.
The 2018 bed edge closely matches the 2016 bed edge in some areas but the patchy margin has
receded waterward in many areas (Figure 1). Nowhere has the bed expanded landward of the 2016
margin. Thus, the geoduck planting area proposed in 2016, and permitted by the Corps in 2017, will
not be altered in the application for a Jefferson County conditional use permit.
May 07 2021
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Figure 1. Comparison of 2016 and 2018 Native Eelgrass Bed Edge.