Puget lowland streams

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

In 2015, the condition of Puget Lowland streams was evaluated by collecting data for stream benthic invertebrates, periphyton, water quality, sediment quality, instream and riparian habitat, and land cover data across the region.

This large effort was coordinated by the SAM Coordinator and included staff from King and Skagit counties, San Juan Island Conservation District, U.S. Geological Survey (USGS), Ecology's Environmental Assessment Program, Puget Sound Partnership, and a myriad of laboratories. 

The science team's recommendations for the streams trend monitoring program are  included in the report. The Stormwater Work Group (SWG) will make adjustments to the SAM Puget lowland stream monitoring program based on recommendations from the report and further discussion by the SWG's committees.

Washington State Department of Agriculture collaborated with SAM receiving waters study to assess the presence and magnitude of pesticides in stream sediments. Final data report, "Pilot Study of Pesticides in Washington State Stream Sediment" published in December 2018 is available in the WSDA Natural Resources Assessment Section Publications.  

Study goals and design

Stakeholders, including municipal stormwater permittees in Western Washington want to know how stream health changes over time in Puget Lowland streams as the area urbanizes and stormwater controls are implemented more broadly.

Puget Lowland ecoregion streams were monitored at 105 sites that were randomly selected to represent the total 1,668 miles (2,685 km) of wadeable stream in the region. The random probabilistic design allows spatial characterization of large areas across the region that would not otherwise be possible and uses modest funding and resources.

Other key deliverables and information

Compilation of three photos showing three urban stream sites sampled in this study. The main image shows two scientists taking a water sample. The other two images are scenic.

SAM's stream study collects water, sediment, and benthic macroinvertebrate samples from Puget Sound lowland streams. This study tracks pollution and indicators of stream health trends over time.

This web map represents regional stream sampling from 2015. 

Site selection

Stream sites for SAM monitoring were selected from EPA's Generalized Random Tessellation Stratified (GRTS) randomized Master Sample list, restricted to the Puget Sound lowland ecoregion with a target on small- to mid-size streams. Two distinct strata are being sampled: outside the urban growth area (OUGA) and within the urban growth areas (WUGA).