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 Camas Creek Subbasin lies in south-central Idaho; Camas Creek is the main water body that drains the subbasin. The creek originates in the Camas Prairie and discharges into Magic Reservoir.

Biological and water chemistry data were used to determine if the beneficial uses of the water bodies in the Camas Creek Subbasin were fully supported. When data indicated that beneficial uses were being fully supported, it was recommended that the water bodies be removed from the §303(d) list. When biological data indicated that beneficial uses were not fully supported, water chemistry data were used to identify the source of pollutants impacting beneficial uses. Once a pollutant was identified, load allocations for the appropriate point and nonpoint sources were completed.

TMDLs were completed for 12 water bodies in the subbasin: 11 of the 12 listed water bodies (all but Mormon Reservoir), plus Dairy Creek. TMDLs for Dairy Creek and McKinney Creek should help address sediment and nutrient issues in Mormon Reservoir.

Data indicate that beneficial uses were supported in three of the listed water bodies (Willow Creek, Beaver Creek, and Little Beaver Creek). However, temperature TMDLs were completed on them anyway, as their temperature data indicate that water quality should not be capable of fully supporting beneficial uses.

There were a number of cases in which flow alteration was found to be a source of pollution impacting the water body. However, flow is not considered a "pollutant" under the Clean Water Act, and TMDLs are not required for pollution that isn't caused by a "pollutant." Therefore, TMDLs were not completed for flow alteration.