Current Water Quality Assessment

Use the most recent 303(d) list to be approved by EPA for the purposes of writing discharge permits, watershed characterization, financial assistance funding, TMDL prioritization, and TMDL implementation.



The Environmental Protection Agency (EPA) approved Ecology’s September 2015 submittal of our latest Water Quality Assessment 305(b) report and 303(d) list on July 22, 2016. This is the current water quality assessment and 303(d) list of impaired waterbodies for the state of Washington, including updated assessments for freshwaters.

This Assessment fulfills Washington State’s obligation under the federal Clean Water Act (CWA) §303(d) and §305(b) to identify polluted waters (known as the 303(d) list) as well as report on the status of water quality statewide where data is available.

Ecology submitted the latest Water Quality Assessment and Candidate 303(d) list to EPA on September 28, 2015 for review and approval. Information on the submittal package to EPA and the process for development of the 2014 Water Quality Assessment.

Submittal Package to EPA

Ecology submitted the 2014 Water Quality Assessment and Candidate 303(d) list to EPA on September 28, 2015 for review and approval. The following were part of the submittal package to EPA:

About this latest Water Quality Assessment

This Assessment updates freshwater listings based on data collected during the call for data. Since Washington only updated the marine listings for the 2012 assessment, EPA considers the freshwater 303(d) listings in the current assessment to meet Washington state requirements to submit a 2012 freshwater 303(d) list.

New with this Assessment, we are updating how we map polluted rivers, lakes and streams. We moved from a land-based system (township/range/section) to a water-based (National Hydrography Database) system. The mapping change helps us be consistent with other agencies and states, and is strongly recommended by the Environmental Protection Agency.

Also new with this latest approved Assessment is an enhanced mapping platform called the Water Quality Atlas. The Water Quality Atlas is an interactive search and mapping tool that includes additional layers of information never before available to the public on an easy-to-use mapping application. The user can now see not only map the Water Quality Assessment category results, but can also view the associated water quality standards for a location, areas addressed by Total Maximum Daily Loads (TMDLs) and nearby permitted wastewater discharge outfalls.

Questions about the updates

Background Information on the Draft 2014 Assessment

If you have questions or need specific information on the 2014 assessment, please contact:

Patrick Lizon
Water Quality Program
WA Department of Ecology
P.O. Box 47600
Olympia, WA 98504-7600


Last updated February 2017