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 on 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 National Pollutant Discharge Elimination System (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 the NPDES permits to dischargers. DEQ is in the early stage of developing its Water Quality Management Plan to address implementation of 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.

DEQ plans to convene 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 content of the draft implementation plan. Prior to its finalization and release, DEQ will provide the opportunity for members of the public to provide comments on the draft Water Quality Management Plan. 

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

Additional documents and resources