Clearwater River Watershed Stressor Identification Report

The Minnesota Pollution Control Agency (MPCA) follows a watershed approach to systematically monitor and assess surface water quality in each of the state's 80 major watersheds. A key component of this approach is the Intensive Watershed Monitoring (IWM) program, which includes biological (fish and macroinvertebrate) monitoring to evaluate overall stream health. In 2014, 2015, and 2016 the MPCA conducted biological monitoring at several monitoring stations throughout the Clearwater River watershed. An Index of Biological Integrity (IBI) score was then calculated for the fish (F-IBI) and macroinvertebrate (M-IBI) communities sampled from each station. The biological monitoring results for the watershed were assessed to identify individual stream reaches, referred to using Assessment Unit Identification (AUID) numbers that were not supporting a healthy fish and/or macroinvertebrate population. A reach with low IBI scores (i.e., below an established threshold) is usually considered "impaired" for aquatic life. A total of eight reaches, or AUIDs, in the Clearwater River watershed were determined to have an aquatic life impairment, including segments of County Ditch 23, Beau Gerlot Creek, Poplar River, Tributary to the Poplar River Diversion Ditch, Hill River, Lost River, and Silver Creek.