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Degradation of Benthos
IJC Criteria: An impairment will be listed when benthic macroinvertebrate community structure significantly diverges from unimpacted control sites of comparable physical and chemical characteristics. In addition, this use will be considered impaired when toxicity (as defined by relevant, field-validated, bioassays with appropriate quality assurance/quality controls) of sediment-associated contaminants at a site is significantly higher than controls.
SLR RAP Rationale for Listing: Reduced benthic invertebrate density, diversity, and species richness have been reported in areas of the estuary that are subject to physical disturbance or in close proximity to known discharges or hazardous waste sites. The benthic community is dominated by oligochaetes and chironomids, which are relatively tolerant of organic pollution (Stage I Report, pps. IV-29 to IV-35). In evaluating sediment quality throughout the AOC, the Wisconsin DNR and Minnesota PCA have used the triad approach which combines sediment chemistry, toxicity tests and in situ benthic diversity to give a composite picture of overall sediment "health." The triad approach has demonstrated that the benthic community has been degraded as evidenced by the lack of species diversity and preponderance of pollutant tolerant species.
Draft Proposed Restoration Goals for the Beneficial Use Impairments in the St. Louis River Area of Concern
4.
Degradation of Benthos Goals
Meetings to Develop Restoration Goals for the Beneficial Use Impairements
The Degraded Fish and Wildlife Populations (BUI #2), Degradation of Benthos (BUI #4), and Loss of Fish and Wildlife Habitat (BUI #9) are dealth with by the SLR Habitat workgroup.
The SLRCAC Board of Directors discussed BUI restoration goals at quarterly meetings: May 26, 2004 Minutes.