Puget lowland streams

Stormwater Action Monitoring (SAM) conducts status and trend monitoring in Western Washington streams to answer how stormwater runoff from a broad range of urban conditions affects the health of small wadable streams.

Study goals

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.

The Puget lowland stream study collects water chemistry, sediment chemistry, benthic macroinvertebrate, and periphyton samples, and in-stream and riparian habitat information.

Monitoring study design

Puget lowland stream monitoring follows a random probabilistic survey design which allows spatial characterization of large areas across the region that would not otherwise be possible and uses modest funding and resources.

Since the first round of monitoring in 2015, a few adjustments to the study design were made, based on recommendations from the science team and approved by Stormwater Work Group (SWG), to better answer regional status and trend questions and to improve monitoring efficiency. These new adjustments will be applied to studies starting in 2020.
  • Sample stream conditions every year at fewer random sites, rather than 100 sites every five years to capture year to year variability and improve trend detection power.
  • Stratify the Puget Lowland Region by percent impervious surface of watershed and select sampling sites from each stratified subgroup to better represent the full range of urban and urbanizing conditions in the region.
  • Drop monthly water quality sampling and focus on summer watershed health sampling with targeted water quality parameters.
  • Add continuous monitoring of stream water level to calculate flows or flow metrics.

Completed studies list