Puget Sound nearshore

Washington Department of Fish and Wildlife continues to lead the SAM study to assess chemical contamination using caged mussels in Puget Sound nearshore (IAA-Scope of Work). 

Study questions

Nearshore mussel monitoring assesses status and trends of chemical contamination in nearshore areas. This study will also improve the understanding of stormwater impacts to biota in Puget Sound.   

Study design 

These mussel monitoring from 2021-2025 will follow this Quality Assurance Project Plan. The major changes from the previous study include:

• Expanding nearshore study frame from the Urban Growth Area (UGA) to the whole Puget Sound nearshore. 
• Selecting sites that better represent the full range of urban and urbanizing conditions in the region. Sampling sites are selected from watersheds grouped by their level of impervious surface cover.
• Adding three least-disturbed (reference) sites to monitor.

Key deliverables and documents

2021-2022 Sampling

• Sampling site (2021)
• 2021/22 mussel cage deployment, and retrieval completeness
• 2021/22 Final Report and presentation to SWG

2023-2024 Sampling

• Sampling sites (2023)
• 2023/24 mussel cage deployment, and retrieval completeness
• 2023/24 Final Report and presentation to SWG

Washington Department of Fish and Wildlife (WDFW), with the help of citizen science volunteers, other agencies, tribes, and non-governmental organizations conducted three rounds of mussel monitoring between 2015 and 2020 at over 40 sites along Puget Sound shoreline. Contaminant levels in mussels are a good indicator of water contamination and whether the health of biota in the urban nearshore is improving, deteriorating, or remaining the same. 

Study questions

This project was designed to tell us mussel bioaccumulation levels related to urbanization in the region and how those levels are changing over time.

• Quality Assurance Project Plan (QAPP) provides details on the sites and methods.
• Study site map

Study findings

• The spatial extent of the impacted urban nearshore remains unchanged in Puget Sound. Polycyclinc aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) are correlated with common urbanization metrics.
• The concentration of PAHs, PBDEs, and DDTs in mussel tissue was lower in winter 2019-2020 than previous monitored winters. 
• PCB accumulation appears to be spatially gradual throughout shoreline adjacent to urbanized areas. In contrast, PAHs contamination is relatively low in the region with a few high contamination sites. 
• Declining PBDEs concentrations and stable PCBs concentrations were consisten with the pattern documented by WDFW's TBiOS team in other marine animals.

For more information on these findings, read the full report, view the presentation slides, or download SAM Factsheet #27.

Additional resources

• Interim findings report after monitoring round 1
• Interim findings report after monitoring round 2
• Additional analyses of the SAM mussel monitoring data

The Washington Departments of Health and Ecology's Beach Environmental Assessment Communication and Health (BEACH) program compiled fecal indicator data from 2010 to 2015 in Puget Sound nearshore areas.

Study objectives

This study aimed to assess current bacteria levels in Puget Sound nearshore areas along the urban shoreline, and to assess spatial or temporal data gaps in coverage between existing marine bacteria monitoring programs.

Study findings

Data sets from groups with different sampling goals and methodology showed diverse results. For example, ambient monitoring programs had lower bacteria levels whereas targeted programs that focus on monitoring storm events or source identification had higher bacteria levels. The existing bacteria monitoring programs might provide sufficient information to track bacteria levels in Puget Sound.

• Ecology's Environmental Assessment Program published the final report
• Fact sheet #002 Bacteria data compilation describes key findings

Marine nearshore sediments were sampled at approximately one fathom depth along the urban nearshore in Puget Sound during the summer of 2016, at many of the same sites as the SAM mussels study.

Study objectives

The goals of this study are to assess chemical concentrations in the Puget Sound urban nearshore sediments and, in the long term, to monitor how nearshore health changes over time.    

• Quality Assurance Project Plan (QAPP) provides information on the sites and study design.
• Study site map

Study findings

The concentrations of metals and organics in nearshore sediment were relatively low in the Puget Sound Urban Growth Area nearshore. Natural variables, such as ocean currents movement appear to govern spatial variation of sediment quality in the area. Lead, copper, and zinc concentrations were only weakly related to urban land use metrics.

For more information on these findings, read the final report or SAM fact sheet #10. Additional analyses are included in this SAM technical memo.