Lower Columbia urban streams

Study goals

Stakeholders, including municipal stormwater permittees in Clark and Cowlitz counties, want to know how urban stream health changes over time as the area urbanizes and stormwater controls are implemented more broadly.

Study design

This monitoring is designed to assess the current stream conditions and eventually answer the question:  Are the quality and biota conditions of receiving waters in the region improving with broad implementation of required stormwater management practices?

The Lower Columbia urban streams study collects water and sediment chemistry, in-stream and riparian habitat information, and benthic macroinvertebrate samples. Streamflow and temperature are continuously monitored at each site.

Detailed information about the study design, sampling schedules, and more is in the Quality Assurance Project Plan (2020), Addendum 1 (2021), Addendum 2 (2023), and Addendum 3 (2024).

All data are available for download from our EIM database.

Sampling locations

Urban stream sites in the municipal stormwater permitted area in Clark and Cowlitz counties were hand-picked for monitoring. Each year we visit eight or nine sites. The same five trend sites are monitored every year and the other status sites are monitored once every five years. Open the map below to explore the current sampling locations.