Puget Sound nearshore

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

Study goals

Stakeholders — including municipal stormwater permittees — in Western Washington want to know the current status of Puget Sound nearshore health. They also want to know if stormwater management actions are collectively protecting and recovering nearshore habitat and wildlife.

Study design

Puget nearshore monitoring studies follow probabilistic survey design. Since the first three monitorings in 2014 - 2019, the study design has been modified to better answer regional status and trend questions and to improve monitoring efficiency. 

Puget nearshore monitoring focuses bioaccumulation of pollutants in caged mussels to evaluate the current status and trend of nearshore conditions. A total of 33 randomly selected sites with three least-disturbed sites across the whole Puget Sound nearshore and three baseline samples are monitored biannually.  

Study findings 

Previous Puget Sound nearshore studies (2014 - 2019) focused on evaluating the current status of nearshore conditions by studying nearshore sediment quality, bioaccumulation of pollutants in mussels, and bacteria levels. 

Previous mussel monitoring found that the contamination levels of many organics — including polycyclinc aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) — were highly correlated with the urban metrics, such as the percentage of impervious surface cover in the region (Mussel study factsheet).

However, a sediment chemistry study done in 2016, showed a relatively low correlation between sediment contamination levels and urban metrics. Instead, ocean currents driving movement of sediment tend to govern the spatial variation of sediment quality in the area (Nearshore sediment factsheet). 

See the completed studies list below for more details. 


SAM mussels study uses native blue mussels in cages anchored to Puget Sound beaches to filter water for three winter months.
SAM nearshore marine sediment study samples fine sediment at 6 feet below the mean low low water line in the Puget Sound nearshore.  

On-going study contract details

Completed studies list