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 and sediment chemistry, in-stream and riparian habitat information, benthic macroinvertebrate, and periphyton samples.
Puget lowland stream sites are selected following a random probabilistic survey design which allows spatial characterization of large areas across the study region that would not otherwise be possible. It also uses modest funding and resources.
Study design adjustment
Since the first SAM streams monitoring in 2015, a few study design adjustments were made to better answer regional status and trend questions and to improve monitoring efficiency. These adjustments are applied to studies starting in 2020.
- Stream conditions sampled every year at fewer random sites (n=33) to year variability and improve trend detection power.
- Sites are stratified by percent impervious surface of the contributing watershed into four categories to better represent the full range of urban and urbanizing conditions in the region.
- Sites are sampled in the summer only for watershed health (biota, stream, and riparian condition) with targeted water and sediment quality parameters.Monthly water quality was dropped.
- Continuous monitoring of stream water level starting the October before the summer sampling to calculate flows or flow metrics at each site.