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.

This document was prepared collaboratively under a Memorandum of Agreement by DEQ, the Nez Perce Tribe, and the EPA. It was submitted jointly by DEQ and the Nez Perce Tribe to the EPA for approval in March 2004.

Water temperatures are elevated above water quality standards at all monitoring locations throughout the subbasin. Logging, roading, mining, grazing, and agricultural activities have reduced shading of surface water. Point source contributions to water temperature increases are minor except for the effects of the effluent from the Grangeville wastewater treatment plant.

At the completion of the assessment of temperature, it was concluded that many unlisted stream segments throughout the subbasin need heat load reductions to meet water quality standards as well. Therefore, temperature TMDLs were established for an additional 58 unlisted stream segments throughout the subbasin.

Coarse sediment, which effects salmonid spawning, has degraded water quality in the upper basin. Nonpoint sediment sources in the South Fork Clearwater River are mainly agricultural and grazing areas (10 – 30 times natural background) and forested areas (2 times natural background). Point sources of sediment include five municipal wastewater treatment plants, suction dredge mining, and construction and industrial storm water runoff.

Bacteria and nutrients in Threemile Creek greatly exceed state standards and U.S. Environmental Protection Agency guidelines. The majority of the bacteria are thought to be from livestock grazing; the majority of the nutrients are from the Grangeville wastewater treatment plant.

It is recommended that Lucas Lake and seven streams listed as impaired by sediment and one stream segment each listed as impaired by bacteria, nutrients, ammonia, and a lack of dissolved oxygen be removed from the §303(d) list.