Marine nearshore mussels

Stormwater Action Monitoring (SAM) conducts status and trend monitoring in Western Washington streams and nearshore marine waters.

This study of contaminants in urban nearshore caged mussels is led by the Washington Department of Fish & Wildlife (WDFW) and sample collection will take place over two winters. The first round of sampling was winter of 2015/16 and a second round in winter 2016/17.

Study goal and expectations

The goal of this study is a status assessment of contaminants found in biota in the Puget Sound urban nearshore.

WDFW presented preliminary findings and recommendations to shape the mussel trend monitoring at the June 1, 2017 SAM Symposium and are also given in the final report. The Stormwater Work Group (SWG) will make adjustments to the SAM mussel trend monitoring program based on recommendations from the report and further discussion by the SWG's technical committees.

nightime compiliation photo of person working on beach and  a cage of mussels for sampling study. Dock with lights in background.

SAM mussel study uses native blue mussels in cages anchored to Puget Sound beaches to filter water for three winter months. This study evaluates pollutant exposure in the urban nearshore environment.

This map shows all the nearshore mussel sampling sites for the first round of SAM mussel sampling.

Study objectives

Stakeholders — including municipal stormwater permittees — in Western Washington want to know if stormwater management actions are collectively protecting and recovering Puget Sound nearshore habitat and wildlife.

The SWG identified the following specific objectives for this study:
  • Evaluate the range of chemical contamination in urban nearshore biota, using blue mussels (Mytilus spp.) as the primary indicator organism, from 40 sites.
  • Measure the magnitude of contamination in the mussels and compare to known biotic effects.
  • Provide recommendations for future nearshore trends monitoring with mussels to answer questions about stormwater management.
  • Compare SAM mussel monitoring to ongoing WDFW Mussel Watch efforts in Puget Sound.

Agreements with WDFW describe the sampling and data analysis tasks

Site selection

Nearshore monitoring sites for SAM were drawn using EPA’s spatially-balanced probabilistic random stratified approach. The Puget Sound shoreline master list was restricted to the nearshore along 2011 urban growth areas (UGA) in Puget Sound. Puget Sound Mussel Monitoring sample design provides more information. Each site represents a length of 800 meters along urban nearshore areas.

Round 1 key deliverables

Round 2 tasks and key deliverables

Tasks 1-7: Preparation and deployment of mussels and sampling cages

Tasks 8-12: Laboratory analysis

  • Mortality report and biological metrics of deployed mussels
  • Chemistry quality assurance, upload 2017/18 data to EIM

Tasks 13-14: Data analysis, report, communications

  • Presentation
  • Final report on Round 2 mussel monitoring
  • Fact sheet