Cottonwood River Watershed Monitoring and Assessment Report

The Minnesota Pollution Control Agency (MPCA) conducted a two-year intensive watershed monitoring (IWM) project in the Cottonwood River watershed. During this two-year sampling period, 81 stations across 59 stream reaches were monitored for fish, macroinvertebrates, and water chemistry. The biological data that was collected was used to determine the health of the streams and lakes by assessing the health of the aquatic community (fish and macroinvertebrates in streams, fish and plants in lakes). Of the reaches assessed, 20% were found to fully support aquatic life and 22% of the reaches did not support aquatic life. This watershed has had a significant amount of hydrological alterations in the form of drain tile, straightening of streams and the addition of ditches. These alterations have negative effects on the stream communities due to the lack of habitat, increased sedimentation, and increased large flow events. The presence of hybridization between fish species and the large number tolerant species are signs of unhealthy stream communities, directly linked to habitat degradation. Even though a majority of the watershed has had a significant amount of hydrological alterations there are still streams that have not been straightened and still provide good habitat for the fish and macroinvertebrate communities. In these streams, sensitive fish were present and the habitat was considered good. There were only nine stations that had habitat classified as good and no stations exhibited excellent habitat.