Columbia River

Project: Water Quality Management Plan for the Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load

Water Quality Limited Parameters: Temperature

Pollutants: Heat

Status: In development

Project Area: Oregon's portion of the Columbia River, which stretches from the river's mouth near Astoria to river mile 309.

Project summary

Oregon has identified the Columbia River as impaired for high water temperatures in the state's Integrated Report, which details the conditions of the state's waters. The Columbia River has high water temperatures during the summer and early fall (June through October). During these months, water temperatures exceed the biologically based numeric criteria established to protect aquatic life, such as salmon, that have adapted to cold water.

In 2020, the EPA developed a pollution budget, known as a Total Maximum Daily Load or TMDL, to identify the sources contributing to hot water temperatures and to determine the maximum amount of heat the Columbia River can receive and still meet applicable state and tribal water quality standards. The TMDL provides an allocation, or allowable amount of excess heat, to three major sources: mainstem dams, major tributaries, and permitted NPDES discharges.

Oregon and Washington are responsible for implementing measures to improve water conditions for aquatic life by cooling the river through changes to dam operations, increasing shade along major tributaries, and implementing NPDES permits to dischargers. DEQ is developing its Water Quality Management Plan to implement the 2020 EPA TMDL as described in Oregon Administrative Rules 340-042-0040(4)(I). This plan will identify the entities responsible for reducing their contributions of heat in the water and will outline the strategy and schedule for achieving the required reductions specified in the TMDL.

For more information on the development of Oregon's WQMP for the Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load, email TemperatureWQMP.Columbia@deq.oregon.gov. 

Public Comment Opportunity:

On Oct. 5 DEQ released the draft Columbia River Temperature WQMP for a 45-day public comment period. Written comments are due by 5:00 p.m. Pacific Time on Nov. 19, 2026.

Submit written comments:

By mail:
Oregon DEQ
Attn: David Gruen, Columbia River Coordinator
700 NE Multnomah St., Ste. 600
Portland, OR 97232

By email: TemperatureWQMP.Columbia@deq.oregon.gov

For more information, view the fact sheet available on DEQ's Public Notices web page. 

DEQ plans to present the final WQMP for issuance as a DEQ Director Order in Fall 2026. For more information on the development of Oregon's WQMP for the Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load, email TemperatureWQMP.Columbia@deq.oregon.gov. 

• Draft Columbia River Temperature Water Quality Management Plan (Redline)
• Draft Columbia River Temperature Water Quality Management Plan (Clean)

Local advisory group

In February and March 2026, DEQ convened a local advisory group composed of designated management agencies, Tribal governments, industry groups, environmental organizations, and other interested parties to provide feedback and recommendations on the draft implementation plan. Click on the Meeting Schedule link below to view meeting agendas, presentations, and summaries.

• Advisory Group Charter
• Advisory Group Roster
  

Additional documents and resources