Clearwater River Watershed Total Maximum Daily Load

A TMDL is a calculation of the maximum amount of pollutant that can enter a waterbody without causing the concentration of the pollutant within the waterbody to exceed water quality standards. A TMDL report also identifies the pollutant sources causing the impairment, and allocates necessary pollutant load reductions to sources. The Clearwater River Watershed TMDL addresses 44 impairments of aquatic life and recreation that have been found within 27 stream reaches and 3 lakes within the watershed. There are 14 aquatic consumption impairments for mercury in fish tissue found in 10 stream reaches and 4 lakes that are not addressed in this TMDL. Total suspended solids (TSS) impairments were found in five reaches of the Clearwater River and Nassett Creek. Aquatic life impairments due to low dissolved oxygen (DO) levels have been identified in 10 reaches of tributaries of the Clearwater River. Low index of biological integrity (IBI) scores have resulted in macroinvertebrate IBI (M-IBI) impairment designations for 3 reaches and fish IBI (F-IBI) impairments for 7 stream reaches within the Clearwater River Watershed. A river eutrophication impairment was identified in one reach of the Clearwater River. Impairments of recreational safety due to chronically high concentrations of Escherichia coli (E. coli) bacteria have been found along 15 reaches of the Clearwater River and its tributaries. Aquatic recreation is impaired by eutrophication (excess nutrients) in 3 lakes.