The St. Louis River is listed as a Great Lakes Area of Concern (AOC) under the Great Lakes Water Quality Agreement of 1987 and is the only AOC in Minnesota. The AOC has several “Beneficial Use Impairments” including loss of fish and wildlife habitat, restrictions on fish and wildlife consumption, excess loadings of sediment and nutrients, and degradation of aquatic invertebrate communities (benthos).
The Minnesota Pollution Control Agency conveyed a need to identify improvements and advance progress toward removing use impairments and eventual AOC delisting. In response, EPA ecologists worked closely with state agency staff to develop analytical tools to assess conditions in the river. These tools included indices of community health for benthos, predictive models for floating and submerged aquatic vegetation, a probabilistic sample design approach for assessing water quality, and assessment approaches that associate specific remediation sites with contaminant-related effects in fish (tumors and deformities, contaminant biomagnification). The tools have been used for determining which areas of the St. Louis River require sediment remediation and habitat restoration, designing habitat restoration, and assessing progress toward delisting targets. These and additional tools now being developed will also be useful for post-restoration monitoring and future ecological assessments.
“EPA ORD’s Mid-Continent Ecology Division has been instrumental in providing data, analytical expertise and guidance to support the Minnesota Pollution Control Agency’s efforts to remove Beneficial Use Impairments (BUI’s) in the St. Louis River Area of Concern (AOC) in Duluth, MN and Superior, WI. This AOC is the largest and most complex of the 43 legacy pollution sites surrounding the Great Lakes in the U.S. and Canada. EPA’s work on aquatic macrophyte models, bio-accumulative compounds in fish tissue, benthic invertebrate communities and spatial data sets has accelerated the implementation of our plan to complete all project work in the AOC by 2020 so that BUI’s can be removed by the target date of 2025,” said Minnesota Pollution Control Agency Commissioner John Linc Stine.