Mussel Watch

Mussel Watch

The Mussel Watch subcommittee completed a two-year report detailing contaminant levels in Snohomish County marine waters including possible sources and program recommendations.  The report analyzes contaminant level data from 2006 – 2011 collected from mussels at eight sites in Snohomish County.  The report addresses how Mussel Watch can be used to monitor the effectiveness of Puget Sound cleanup efforts.  For example, decreasing levels of butyltins were found in mussels in Everett Harbor following the ban of butyltin-based vessel antifouling paints.  The report recommends the continuation of the Snohomish County Mussel Watch Program to monitor contaminant level trends in Snohomish County relative to the rest of Puget Sound and the West Coast. 

View the report


Since 2007, the Snohomish County Marine Resources Committee has coordinated the Snohomish County Mussel Watch Program.  The goal of this program is to obtain current information on the relative concentrations of the chemical contaminants in the nearshore waters of Snohomish County.  Through the Mussel Watch program, mussels are sampled by volunteers and sent to a laboratory for tissue analysis. 

The data from Snohomish County are included in NOAA's Mussel Watch database. Snohomish County’s Mussel Watch program is one subset of the NOAA's National Status and Trends Mussel Watch program, which has been discontinued.  This program turned into the WDFW Caged Mussel Study.

WDFW Caged Mussel Study

In 2010 and 2012, the MRC worked with regional project partners from Washington Department of Fish and Wildlife (WDFW) and Washington Sea Grant on the regional expansion of the Mussel Watch program. The expansion project modeled Snohomish County’s Mussel Watch program using citizen scientists for mussel collections.  Mussels were successfully sampled at over 25 sites across Western Washington by citizen scientists from local volunteer groups and WDFW.

In 2015 and 2016, the MRC assisted with three caged mussel sites within Snohomish County. Mussel cages were secured to various beaches in October, 2015 and retireved in February, 2016. They were then sent to WDFW for analysis. 

The report detailing the successful regional expansion of the Mussel Watch Program is available from WDFW. View the publication

Photo: Amy Johnson


Data trends from the NOAA and WDFW programs are used to monitor the impact of environmental contaminants and events such as oil spills and the effectiveness of management decisions. The data show spatial differences between the more rural Port Susan to the north and the more urban developed area to the south of the Snohomish River.  Generally contaminants are lower to the north and higher to the south, with mercury being the exception.  There are also differences between wet and dry seasons.  These trends are presented in the Mussel Watch Report for a compilation of selected parameters.  The report, completed in June 2011, summarizes data through Summer 2009. 

Edmonds Ferry National Mussel Watch Site Mid-Intertidal Summertime Photo Series 

View the 2007-2012 Edmonds Ferry photo series. These photos were taken by Alan Mearns of NOAA.

These photos capture changes in mussel recruitment.  Over time such photo series can be used to monitor cycles in conspicuous intertidal biota.  Photo series could be used to help better understand the interannual variations in mussel populations that Mussel Watch volunteers have observed at Snohomish County Mussel Watch sites.

NWSC Benchmarks Achieved:
Marine Water Quality, Science, Education & Outreach

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Mussel Watch