Cedar River Watershed Biotic Stressor Identification

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, an Index of Biological Integrity (IBI) scores are calculated, which provides 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 Cedar River Watershed. There were 19 reaches identified with biological impairment in the Cedar River Watershed (Table 3). In the Cedar River Watershed, there were 5 streams with fish and macroinvertebrate impairments, while the remaining 14 were impaired for only macroinvertebrates.