Mississippi River (Winona) Watershed Biotic Stressor Identification Report

Over the past few years, the Minnesota Pollution Control Agency (MPCA) has substantially increased the use of biological monitoring and assessment as a means to determine and report the condition of the state's rivers and streams. This basic approach is to examine fish and aquatic macroinvertebrate communities and related habitat conditions at multiple sites throughout a major watershed. From these data, Index of Biological Integrity (IBI) scores are calculated, which provide a measure of overall community health. If biological impairments are found, stressors to the aquatic community must be identified. Stressor identification is a formal and rigorous process that identifies stressors causing biological impairment of aquatic ecosystems and provides a structure for organizing the scientific evidence supporting the conclusions (Cormier et al. 2000). In simpler terms, it is the process of identifying the major factors causing harm to aquatic life. Stressor identification is a key component of the major watershed restoration and protection projects being carried out under Minnesota's Clean Water Legacy Act. This report summarizes stressor identification work in the Mississippi River-Winona Watershed. There were 10 reaches identified with biological impairment in the MR-Winona Watershed. However, this report addresses 12 reaches – the 10 identified and two with imminent impairments.