Development of a Copper Criteria Adjustment Procedure for Michigan's Upper Peninsula Waters

Results of laboratory tests and water quality monitoring revealed that elevated copper concentrations in several Upper Peninsula (U.P.), Michigan streams were not associated with toxic effects or adverse impacts on resident aquatic macroinvertebrate or fish communities. These results suggest that Michigan's current copper standard may be overprotective for streams and rivers in the U.P., and perhaps in other State waters as well. This research program was designed to develop a copper criteria adjustment procedure for U.P. waters using a scientifically defensible approach that accounts for site-specific conditions. The program goal was to identify water quality parameters that mitigate copper toxicity and employ them in the derivation of site-specific copper criteria for U.P. waters. Recent research indicates that dissolved organic carbon may influence copper toxicity more than water hardness. Therefore, we selected U.P. rivers and streams with a wide range of water hardness (range: 15 - 213 mg/L CaCO3) and dissolved organic carbon (DOC) (range: