The federal Clean Water Act requires that states and tribes restore and maintain the chemical, physical, and biological integrity of the nation's waters. States and tribes must adopt water quality standards necessary to protect fish, shellfish, and wildlife while providing for recreation in and on the waters whenever possible.

Section 303(d) of the Clean Water Act establishes requirements for states and tribes to identify and prioritize water bodies that are water quality limited (i.e., water bodies that do not meet water quality standards). States and tribes must periodically publish a priority list of impaired waters, currently every two years. For waters identified on this list, states and tribes must develop water quality improvement plans known as total maximum daily loads (TMDLs) that establish allowable pollutant loads set at levels to achieve water quality standards.

The Clark Fork-Pend Oreille subbasin lies in western Montana, northern Idaho, and northwestern Washington. The subbasin is the source of the water that enters and leaves Lake Pend Oreille, the largest and deepest natural lake in Idaho. Inflow and outflow of the lake are regulated by hydroelectric facilities.

The Pend Oreille portion of this subbasin assessment examined 11 streams, one major river, and two lakes. Of the 11 streams, five were water quality impaired and required load allocations, primarily for sediment. Both Lake Pend Oreille and the Pend Oreille River were found to fully support their beneficial uses and were recommended for delisting.

The Clark Fork portion of this subbasin assessment was tabled until its scheduled due date in 2004. Insufficient time to complete the assessment and the prospect of more data available at that time drove this decision.

Pack River Nutrients Total Maximum Daily Load

Pend Oreille Lake Tributaries Temperature Total Maximum Daily Loads