Evaluating Potential Effects of Mining on Aquatic Biota in Northern Minnesota

As part of National Pollutant Discharge Elimination System (NPDES) permitting, the effects from discharges on receiving waters need to be evaluated on a periodic basis.  In an effort to evaluate the potential effects of mining activity and related discharge on aquatic biota in northern Minnesota, we conducted a field study in 2010-2011 to characterize the fish and benthic invertebrate communities in five streams (three located near mining sites and two reference streams not influenced by mining) and also measured a suite of water chemistry parameters and metal concentrations in the study streams. Biological community indices were evaluated against known toxic constituents to determine potential effects to overall taxa richness and composition. In addition, we conducted whole effluent toxicity (WET) tests using Ceriodaphnia dubia to serve as a surrogate measure of potential adverse effects of mining to downstream biota. Results of biological community analysis and WET tests will be discussed in the context of continued mining activity in this area and the related ecological implications.