St. Louis River BUI Monitoring Assessments - Degraded Benthos and Restrictions on Dredging BUIs


Additional sediment quality information is needed in some sediment assessment areas of the St. Louis River AOC to help determine if remediation will be required. Wisconsin DNR will collect sediment samples from locations where recent sediment characterization results showed toxicity and/or exceedances of the probable effect concentrations for select metals and/or organic contaminants (namely PAHs). Sampling is needed to assess the contribution of contaminated sediments in select areas to beneficial use impairments (BUI) including, but not necessarily limited to, degraded benthos, dredging restrictions, and fish & wildlife habitat.


Sediment samples wil be collected and analyzed for invertebrate toxicity, site-specific chemicals, and macroinvertebrate assemblages. Results will be evaluated using the triad approach for sediment quality as well as the macroinvertebrate index developed for this AOC.


There are multiple nested outcomes from this monitoring including: an assessment of sediment quality, an evaluation of site-specific contributions to BUIs, and the identification of any reasonable actions to address BUIs. In addition, recommendations will be made for next steps including "no action" if that is supported by the data and a specific regulatory program is identified that will address impairments in a practical timeframe.

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