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Columbia River

DEQ works closely with local, state and federal agencies as well as the public to improve water quality in the Columbia River and its tributaries. The U.S. Environmental Protection Agency identifies the Columbia as one of the nation’s seven “great water bodies” in need of heightened protection from environmental harm.

DEQ oversees several Total Maximum Daily Load, known as TMDL, plans to help reduce pollution and toxics in the Columbia. TMDLs calculate the maximum amount of a pollutant that a water body can receive and still meet water quality standards.

Total dissolved gas water quality standard modification

Mainstem Columbia River

On Nov. 21, 2024, the Oregon Environmental Quality Commission approved a five-year order approving a modification to Oregon’s total dissolved gas water quality criteria on the mainstem Columbia River. The five-year modification order allows for daily average total dissolved gas levels up to 125 percent saturation, above the statewide standard of 110 percent saturation, to allow for increased spill over the lower four mainstem Columbia River Dams. Increased spill over the dams improves conditions for populations of Endangered Species Act listed salmon and steelhead. 

Additional documents and resources

On May 18, 2020, EPA established the Columbia and Lower Snake Rivers Temperature Total Maximum Daily Load.

Contact

David Gruen
Columbia River Coordinator 
503-719-2282