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.

The Little Wood River Subbasin lies in south-central Idaho. The river originates in the Pioneer Mountains of the Sawtooth National Forest and discharges in the desert plains at the Big Wood River.

Nutrients were measured in the form of total phosphorus and total inorganic nitrogen. High annual averages of total inorganic nitrogen, combined with elevated total phosphorus levels indicate that nutrients could be at levels that are capable of contributing to nuisance aquatic growth. Nutrient TMDLs have been completed for Fish Creek (both above and below Fish Creek Reservoir) and for the Little Wood River from Silver Creek to the Big Wood River.

Sediment was measured in the water column as total suspended solids and as percent fines. Where it was found that percent fines were elevated, stream bank erosion inventories were completed to determine if stream banks were the source of the sediment.

Stream bank erosion TMDLs for sediment were completed on Dry Creek, both segments of Fish Creek, and the Little Wood River from Silver Creek to the Big Wood River.

Bacteria and temperature are both numeric water quality standards and, as such, have numeric values that have to be met. Where numeric bacteria standards were exceeded, additional samples were collected; a bacteria TMDL was completed for Fish Creek above Fish Creek Reservoir.

Where water temperatures were elevated, the canopy cover of the water bodies was measured to develop TMDLs. Temperature TMDLs were completed on Loving Creek, Muldoon Creek, both segments of Fish Creek, and the Little Wood River.

Flow alteration has been identified as pollution for many of the water bodies. However, the U.S. Environmental Protection Agency does not believe that flow alteration is a pollutant as defined by the Clean Water Act. Since TMDLs are not required for water bodies impaired by pollution but not pollutants, TMDLs were not developed for flow alteration. The water bodies with flow alteration have been identified as such and put on a list of water bodies polluted by flow alteration.

Where biological and water chemistry data indicated that beneficial uses were being fully supported, those water bodies were proposed for removal from the §303(d) list. Both Fish Creek Reservoir and Little Wood River Reservoir were recommended for removal.