Stressor Identification Update Buffalo River and Upper Red River of the North Watersheds

The Minnesota Pollution Control Agency (MPCA) utilizes a watershed approach to systematically monitor and assess surface water quality in each of the state’s 80 major watersheds on a rotating 10-year basis. A key component of this approach is Intensive Watershed Monitoring (IWM), which includes biological (i.e., fish and macroinvertebrate) monitoring to evaluate overall stream health. Based on the results of biological monitoring, an Index of Biological Integrity (IBI) score is calculated for each fish (F-IBI) and macroinvertebrate (M-IBI) monitoring visit to a stream reach. A reach with an IBI score below an established class threshold may be assessed as “impaired”, or unable to support its designated
beneficial use, for aquatic life. Stressor identification (SID) is subsequently performed on reaches with a bioassessments impairment to determine the probable causes, or “stressors”, that are likely contributing to the impairment. The findings from SID are then used to support the development of Watershed Restoration and Protection Strategy (WRAPS) and Total Maximum Daily Load (TMDL) reports, which help inform local water planning efforts to address the impaired condition.