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). Every two years, states and tribes must publish a priority list of impaired waters. For waters identified on this list, states and tribes must develop water quality plans known as total maximum daily loads (TMDLs) that establish allowable pollutant loads set at levels to achieve water quality standards.

The Lower North Fork Clearwater River Subbasin is located in north central Idaho, primarily in Clearwater County. Situated around Dworshak Reservoir, all streams flow directly or indirectly into the reservoir. Dworshak Dam was completed in 1971, and the reservoir attained full pool two years later. At full pool the reservoir is 54 miles long, 2 miles across, and has a maximum depth of 480 feet. There is no passage for migrating fish at Dworshak Dam.

Over the past 100 years, human activities, primarily silvicultural, have changed the landscape of the subbasin, and these alterations are the primary reason TMDLs were developed for the Lower North Fork Clearwater River Subbasin.

Twelve TMDLs were written for seven water bodies for three separate pollutants. Seven water bodies were recommended for future §303(d) listing for temperature. The pollutants in the subbasin are mainly from nonpoint sources, as the only point source is the wastewater treatment plant in Elk River. For sediment, the main sources are background, roads, mass failures, and stream bank and riparian area erosion. For bacteria, the main sources are cattle and other livestock, wildlife, and humans. For temperature, the source is solar radiation.