Determine Baseline and Sources of Contaminant Loadings to the Great Lakes

To better understand the quality of water flowing into the Great Lakes, the USGS is conducting water-quality analyses for nutrients, sediment, and toxic substances and estimating the amount (load) of these substances for tributaries to the Great Lakes. Information on the occurrence and distribution of contaminants is needed to provide baseline information, measure progress towards restoration goals, and assess new threats. This information will provide an understanding of how contaminants reach the Great Lakes, and where they come from, so that the effects of future actions can be assessed and predicted.