River & stream water quality monitoring

We monitor water quality at nearly 100 river and stream stations throughout the state to understand the health of waterways. Our science offers residents and policymakers credible data to make informed choices for rivers and streams in Washington. All of our data are available to download.

We created a Freshwater Quality Index to compare stream health at different locations.

Learn about our methods, how to use our data, and about our data quality assurance. You can read our reports and publications or contact us.

Our river & stream data

Reports and publications

Each water year, from Oct. 1 through Sept. 30 of the following year, our freshwater scientists create a water quality annual report, summarizing that year's data.