Snohomish County Mussel Watch Program

Mussel Watch Report Available for download

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. 

Click here to view the report.

Sampling at Hat IslandOverview

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.  Click here to view the publication.  


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 

Mussels at the Edmonds Ferry Mussel Watch site in 2008.Click here to 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

News Articles

Penn Cove mussels to help track pollution flowing into Puget Sound

WDFW's 2015-2016 Caged Mussel Watch program deployed mussel cages along 73 sites within the Puget Sound. This study will help collect data on the contaminant levels within Washington's waterways.

Click here to read the article.

Mussels: Unlocking secrets to what's in the water

Results from the 2012-2013 Cage Mussel Study show that 100 percent of sampled sites contain trace levels of toxic PCBs. The study also reveals that remote areas along the Sound contain less contaminants, while mussels in more heavily polluted areas of downtown Seattle did not survive the experiement.

Click here to read the article. 

Mussel Memory: How a long term marine pollution program got new life

Dr. Alan Mearns, NOAA Senior Staff Scientist posted to the NOAA Office of Response and Restoration blog about the history of the Washington state Mussel Watch program and the key role of citizen science volunteers in giving the program new life.

Click here to read the blog. 

Volunteers gathering mussels not for meals but to gauge health of shoreline waters

The Everett Herald featured a front-page article on the MRC Mussel Watch Program and the 2012 winter sampling at the Edmonds Ferry site sampling on Saturday, February 4, 2012. 

Click here to view the article.