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Title: Characterization of Salinity and Temperature Patterns in a Large River Delta to Support Tidal Wetland Habitat Restoration

Abstract

Although the Snohomish River estuary remains the second largest tidal wetland complex in Puget Sound, approximately 90% of pre-settlement habitat has been disconnected from tidal exchange. This estuary is currently the focus of the largest restoration effort in Puget Sound, with opportunity to restore tidal exchange to over 50% of pre-settlement levels. The Snohomish River also currently supports populations of all anadromous Pacific salmon species, including Endangered Species Act listed Chinook (Oncorhynchus tshawytscha), steelhead (O. mykiss), and bull trout (Salvelinus confluentus). The combination of extant anadromous Pacific salmon populations, large existing tidal wetland complexes, and large restoration potential make the Snohomish River estuary a great opportunity to benefit salmon population recovery and conservation efforts. To support restoration planning and effectiveness monitoring, we developed baseline characteriza- tions of key physical attributes (salinity and temperature). Our results indicated that brackish (0.5–30 ppt) conditions extended farther upriver than previously described, with distributary channels downstream of the middle mainstem and lower Ebey Slough remaining brackish throughout most of the year. During extreme low flows (< 0.65 m3 s-1), salt water (> 0.5 ppt) can at times intrude throughout the distributaries and up to river kilometer 15.9 above the first bifurcation. We also observed temperaturesmore » exceeding stress thresholds for juvenile salmonids throughout the estuary from July through September, a period that overlaps with juvenile rearing. This research is timely with several large restoration projects scheduled for construction by 2020, and these baseline characterizations can be used to evaluate restoration responses, as well as to inform project prioritization and monitoring.« less

Authors:
 [1];  [2];  [3];  [1];  [4];  [5];  [6];  [7];  [1];  [1]
  1. NOAA
  2. BATTELLE (PACIFIC NW LAB)
  3. NOAA Fisheries, Seattle, WA
  4. Tulalip Tribes
  5. Snohomish County
  6. Snohomish County Public Works, Division of Surface Water Management
  7. NOAA Fisheries
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1509869
Report Number(s):
PNNL-SA-136188
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Northwest Science
Additional Journal Information:
Journal Volume: 92; Journal Issue: 1
Country of Publication:
United States
Language:
English
Subject:
Salt intrusion, temperature, Snohomish River estuary, Washington, Puget Sound

Citation Formats

Hall, Jason E., Khangaonkar, Tarang P., Rice, Casimir A., Chamberlin, Joshua, Zackery, Todd, Leonetti, Frank, Rustay, Mike, Fresh, Kurt, Kagley, Anna, and Rowse, Mindy. Characterization of Salinity and Temperature Patterns in a Large River Delta to Support Tidal Wetland Habitat Restoration. United States: N. p., 2018. Web. doi:10.3955/046.092.0105.
Hall, Jason E., Khangaonkar, Tarang P., Rice, Casimir A., Chamberlin, Joshua, Zackery, Todd, Leonetti, Frank, Rustay, Mike, Fresh, Kurt, Kagley, Anna, & Rowse, Mindy. Characterization of Salinity and Temperature Patterns in a Large River Delta to Support Tidal Wetland Habitat Restoration. United States. doi:10.3955/046.092.0105.
Hall, Jason E., Khangaonkar, Tarang P., Rice, Casimir A., Chamberlin, Joshua, Zackery, Todd, Leonetti, Frank, Rustay, Mike, Fresh, Kurt, Kagley, Anna, and Rowse, Mindy. Mon . "Characterization of Salinity and Temperature Patterns in a Large River Delta to Support Tidal Wetland Habitat Restoration". United States. doi:10.3955/046.092.0105.
@article{osti_1509869,
title = {Characterization of Salinity and Temperature Patterns in a Large River Delta to Support Tidal Wetland Habitat Restoration},
author = {Hall, Jason E. and Khangaonkar, Tarang P. and Rice, Casimir A. and Chamberlin, Joshua and Zackery, Todd and Leonetti, Frank and Rustay, Mike and Fresh, Kurt and Kagley, Anna and Rowse, Mindy},
abstractNote = {Although the Snohomish River estuary remains the second largest tidal wetland complex in Puget Sound, approximately 90% of pre-settlement habitat has been disconnected from tidal exchange. This estuary is currently the focus of the largest restoration effort in Puget Sound, with opportunity to restore tidal exchange to over 50% of pre-settlement levels. The Snohomish River also currently supports populations of all anadromous Pacific salmon species, including Endangered Species Act listed Chinook (Oncorhynchus tshawytscha), steelhead (O. mykiss), and bull trout (Salvelinus confluentus). The combination of extant anadromous Pacific salmon populations, large existing tidal wetland complexes, and large restoration potential make the Snohomish River estuary a great opportunity to benefit salmon population recovery and conservation efforts. To support restoration planning and effectiveness monitoring, we developed baseline characteriza- tions of key physical attributes (salinity and temperature). Our results indicated that brackish (0.5–30 ppt) conditions extended farther upriver than previously described, with distributary channels downstream of the middle mainstem and lower Ebey Slough remaining brackish throughout most of the year. During extreme low flows (< 0.65 m3 s-1), salt water (> 0.5 ppt) can at times intrude throughout the distributaries and up to river kilometer 15.9 above the first bifurcation. We also observed temperatures exceeding stress thresholds for juvenile salmonids throughout the estuary from July through September, a period that overlaps with juvenile rearing. This research is timely with several large restoration projects scheduled for construction by 2020, and these baseline characterizations can be used to evaluate restoration responses, as well as to inform project prioritization and monitoring.},
doi = {10.3955/046.092.0105},
journal = {Northwest Science},
number = 1,
volume = 92,
place = {United States},
year = {2018},
month = {1}
}