Water Quality in the Columbia River Basin

Regional Information

By Sub-basin:

Water Quality Standards

Water Quality Standards are the foundation of the water quality-based pollution control program mandated by the Clean Water Act. Water Quality Standards define the goals for a waterbody by designating its uses, setting criteria to protect those uses, and establishing provisions to protect a waterbody from pollutants.

Oregon Water Quality Standards

Idaho Water Quality Standards

Washington Water Quality Standards

Tribal Water Quality Standards

Water Quality Standards in the Pacific Northwest and Alaska

Total Maximum Daily Loads

A Total Maximum Daily Load (TMDL) is a cleanup plan that identifies the amount of a pollutant that a water body can receive and still meet Water Quality Standards (WQS). It also allocates responsibility to polluters for reductions in the pollutant load that are necessary to achieve WQS. A TMDL is required by the Clean Water Act under Section 303(d) for any surface waters included by States or Tribes on their list of impaired waters. TMDLs can be issued by states or EPA. TMDLs that have been started for the Columbia River or its tributaries include:

The links below provide additional information that may be useful or interesting, but is not located on the epa.gov site.

Columbia Mainstem/Snake River
TMDL for Temperature has been delayed
TMDL for Total Dissolved Gas in the Mid-Columbia River and Lake Roosevelt EPA approved 7/21/04
Columbia River Dioxin TMDL (Idaho, Oregon and Washington) Issued by EPA 2/25/91 (PDF) (41 pp., 4.7MB, About PDF)
Lower Columbia River Total Dissolved Gas TMDL (Washington Department of Ecology)
Lower Columbia River Total Dissolved Gas TMDL (Oregon Department of Environmental Quality)
Hells Canyon TMDLs
Lower Snake River Total Dissolved Gas TMDL (Washington Department of Ecology)
North Coast Subbasins: Lower Columbia-Youngs, Lower Columbia-Clatskanie, Necanicum, and Nehalem TMDL for Temperature and Bacteria

Spokane River Basin
Spokane River Dissolved Oxygen TMDL
Spokane River PCBs TMDL

Okanogan River Basin
Lower Okanogan River DDT PCB TMDL (Washington Department of Ecology)
Similkameen River Arsenic TMDL (Washington Department of Ecology

Yakima River Basin

Bonneville Dam Spillgate

Upper Yakima River Basin Suspended Sediment, Turbidity and Organochlorine Pesticide TMDL
Upper Yakima Basin Temperature TMDL
Lower Yakima River Suspended Sediment and DDT TMDL

Walla Walla Basin
Chlorinated Pesticide & PCB TMDL (Washington Department of Ecology)
Temperature TMDL (Washington Department of Ecology)
Conventional TMDL (dissolved oxygen, fecal coliform, nutrients, & pH) (Washington Department of Ecology)
Temperature TMDL (Oregon Department of Environmental Quality)

Umatilla Basin
Umatilla Subbasin TMDLs
Umatilla Tribal TMDL for Temperature and Turbidity issued by EPA 09/28/05

Grand Ronde River Basin
Upper Grande Ronde Subbasin TMDLs for Temperature and Periphyton (Oregon Department of Environmental Quality)

Sandy River Basin
Sandy River Basin Temperature and Bacteria TMDL (Oregon Department of Environmental Quality)

Willamette River Basin
Willamette River TMDLs Approved by EPA on 9/29/06
Columbia River Dioxin (including the Willamette River) TMDL (Idaho, Oregon and Washington) Issued by EPA 2/25/91 (PDF) (41 pp., 4.7MB, About PDF)
Willamette River Mainstem Mercury, Temperature and Bacteria TMDLs (Oregon Department of Environmental Quality)
Lower Willamette Subbasin TMDL for Temperature, Bacteria, Toxics and Mercury
Columbia Slough Chlorophyll a, Dissolved Oxygen, pH, Phosphorus, Bacteria, DDE/DDT, PCBs, Pb, Dieldrin and 2,3,7,8 TCDD TMDL Approved by EPA on 2/25/98
Tualatin River Temperature, Bacteria and Low pH TMDL

Water Quality in the Columbia River Basin

Regional Information

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