Between 1991 and 2000 Flambeau Mining Company (FMC) was required to test sediments in the Flambeau River for heavy metals, both upstream and downstream of the Flambeau Mine site. Additional sediment testing was conducted in the river between 2006 and 2008, and a one-time sampling of sediments in Stream C (a tributary of the Flambeau River that runs across a portion of the mine site) and two on-site biofilter ponds was conducted by FMC in 2008. In addition, the Wisconsin Department of Natural Resources (WDNR) sampled sediments in Stream C, an on-site biofilter pond and a reference stream in 2010.

Dr. Ken Parejko, Professor Emeritus, Department of Biology, University of Wisconsin-Stout, did  an independent analysis of FMC’s sediment data for the Wisconsin Resources Protection Council (WRPC) in April 2009. At that time he concluded:

“Inadequate baseline data and [too few samples], combined with changing sampling procedures make it very difficult to draw any conclusions regarding the presence or absence of a mining-related effect on the sediment of the Flambeau River. The combined observation of statistically significant increased copper concentrations in crayfish (whole-body specimens), walleye (liver tissue) and sediment (when 2008 downstream copper measurements are included) downstream from the mine site raises the possibility of a causal relationship. Unusually high copper and zinc concentrations in a sampling site within the bed of … Stream C indicate a possible entrance-point for some potential toxins into the Flambeau River. In hindsight, having additional historic data from Stream C and the Flambeau River would prove very useful.”

What the future holds regarding heavy metal accumulation in the sediment of the Flambeau River is unknown. Polluted groundwater from the Flambeau Mine site continues to enter the river through fractured bedrock, but, with the end of mandatory sediment testing in 2008, FMC is now “off the hook.”

To see the sediment data submitted by Flambeau Mining Company to the Wisconsin Department of Natural Resources and various reports compiled by the company and others, click on the below links: