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.

Within the subbasin, there are five water quality limited streams, four of which were placed on the Idaho 1998 §303(d) list and one of which (Jenkins Creek) was removed from the list in 1998, but recent monitoring has identified water quality concerns below the original assessment site that necessitate re-listing.

There are clear indications that recreational beneficial uses are not fully supported for the Hog, Scott, Warm Springs, and Jenkins Creeks subwatersheds. However, the available information for cold water aquatic life uses is limited. Support of cold water aquatic life uses cannot be determined specific to nutrient and sediment concentrations due to a lack of aquatic life data. Interpretation of data available for nutrients and sediments is therefore tied to the attainment of full support of downstream waters (Snake River-Hells Canyon TMDL) shown to be impaired due to excessive nutrient and sediment loading. Secondary contact recreation is not supported in Hog, Scott, Warm Springs, or Jenkins Creeks due to exceedances of bacteria standards during the spring and summer months. All listed water bodies exhibit monitored concentrations of total phosphorus that are above the target identified to improve water quality in the Hells Canyon reach of the Snake River.

Bacteria is proposed to be listed for Hog, Scott, Warm Springs, and Jenkins Creeks as a §303(d) pollutant as part of the first §303(d) list submitted by the state of Idaho subsequent to the approval of this TMDL.