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Water Quality Program

Current EPA Approved Assessment

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 marine waters.

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.

View the current Assessment

You can view the listed water bodies for both water quality and contaminated sediment data by using the:


About this latest Water Quality Assessment

This Assessment updates fresh water listings based on data collected during the call for data. 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.

Starting the process for the next Water Quality Assessment

States are required, under the Clean Water Act, to regularly update the Water Quality Assessment (every 2 years). Ecology started the next water quality assessment process this last winter with:

  1. A call for data to seek new water quality data and information for fresh and marine waters in Washington. This new data and information will be used for updating Washington’s Water Quality Assessment. The call for data started in January 2016 and ended in June 2016.
  2. Ecology also conducted a 60-day scoping process to solicit ideas on areas of the Water Quality Policy 1-11, Assessment of Water Quality for the Clean Water Act Sections 303(d) and 305(b) Integrated Report that need to be updated. This Policy guides how Ecology uses data to determine the water quality status for individual waterbodies.

With the approval of the current Assessment, Ecology will now begin a public process to revise the agency policy that describes how listings are made for each water quality category based on the comments we received during the scoping. An invitation to participate in this public process will be sent out via our email listserv in the near future

Contact us for more information

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Last updated July 2016