Lower Minnesota River Watershed Lakes Stressor Identification Report

In recent years, the Minnesota Pollution Control Agency (MPCA) has incorporated the use of biological monitoring and assessment as a means to determine and report the condition of the state’s surface waters. The Minnesota Department of Natural Resources (MnDNR) has developed tools to assess the condition of a broad range of game fish lakes in coordination with the MPCA watershed assessment framework. The basic approach is to collect data from fish communities and related habitats at multiple lakes throughout a major watershed. From these data, an Index of Biological Integrity (IBI) score can be developed, which provides a measure of overall community health. If biological impairments are found, stressors to the aquatic community must be identified.
Stressor identification is the process of identifying the major factors causing the biological impairment of the aquatic ecosystem. It is a key component of the major watershed restoration and protection projects being carried out under Minnesota’s Clean Water Legacy Act.
The Lower Minnesota River Watershed (LMRW) covers an area of 1,760 square miles and includes Sibley and Scott counties, and portions of Le Sueur, Carver, Hennepin, Dakota, Rice, Nicollet, Renville and McLeod counties. There are several local government units, watershed districts, and other watershed management organizations that share the responsibility for maintaining healthy aquatic communities.
This report summarizes stressor identification work for biological impairments to lake fish communities in the LMRW. It provides a summary of possible stressors to lake fish communities. In addition, the report identifies the stressors most likely responsible for the impairments in the watershed and evaluates the available information for each lake. Information from this document can be used by local planning organizations to help establish goals for protection and prioritize restoration efforts.