Clearwater River Watershed Fish based Lake IBI Stressor Identification Report

Over the past couple of years, the Minnesota Pollution Control Agency (MPCA) in coordination with the Minnesota Department of Natural Resources (MNDNR) has substantially increased the use of biological monitoring and assessment to determine and report the condition of Minnesota's lakes. The identification of biological impairments includes the assessment of fish communities of lakes throughout a major watershed. The fish-based lake index of biological integrity (FIBI) utilizes data from trap net and gill net gamefish surveys, as well as nearshore surveys that utilize beach seines and backpack electrofishing to sample nongame fish-communities. From this data, an FIBI score can be calculated for each lake which provides a measure of overall fish community health. MNDNR developed four FIBI tools to assess different types of lakes throughout the state (Table 1-1). More information on the FIBI tools and assessments based on the FIBI can be found at the MNDNR website Although an FIBI score may indicate that a lake fish community is impaired, that alone is not sufficient to assess a lake as impaired for Aquatic Life Use. A weight of evidence approach is used during the assessment process which factors in considerations such as sampling effort, sampling efficiency, tool applicability, location in the watershed, and any other unique circumstances to validate the FIBI score. This report summarizes FIBI stressor identification work in the Clearwater River Watershed (Figure 2-1). The FIBI was used to assess eleven lakes in the Clearwater River Watershed (Figure 2-1; Table 2-1; Table 2-2). Three lakes had repeated nearshore surveys:Whitefish (DOW 04-0300-00), Whitefish (DOW 60-0015-00), and Maple (DOW 60-0305-00).