Blue Earth River Watershed Monitoring and Assessment Report

The Blue Earth River Watershed (HUC 07020009) covers an area of more than 1,500 square miles (1,001,805 acres) in south central Minnesota and north central Iowa. Approximately 80% of the Blue Earth River Watershed lies within portions of Minnesota's Martin, Faribault, and Blue Earth counties, spanning an area from the Iowa border to its confluence with the Minnesota River in the city of Mankato. In 2017, the Minnesota Pollution Control Agency (MPCA) began a two-year, intensive watershed monitoring (IWM) project in Blue Earth River Watershed. This project was designed to assess the quality of the lakes and streams in the watershed through both biological and water chemistry monitoring. MPCA biomonitoring staff evaluated fish and macroinvertebrate communities at 71 unique monitoring stations across 66 assessment reaches of stream. Minnesota Department of Natural Resources (DNR) staff evaluated fish communities in 10 lakes in the watershed. MPCA surface water quality staff in partnership with Faribault County Soil and Water Conservation District (SWCD) and Martin County SWCD completed lake and stream chemistry sampling at 18 stream locations: 16 of which were at the outlets of each major subwatershed and additional locations were sampled on tributaries entering the state from Iowa. MPCA surface water quality staff, in partnership with Faribault and Martin County SWCDs, collected water chemistry samples from 24 lakes to assess the aquatic life and aquatic recreation potential of each lake and stream where sufficient data was available. Results presented in this report indicate significantly degraded water quality and biological communities throughout much of the watershed, as less than a third of streams are fully supporting aquatic life use. Despite significant alterations to hydrologic and ecological function, many reaches of stream were found to harbor diverse and balanced communities that met thresholds.