The Importance of Ground Water in the Great Lakes Region
Water Resources Investigations Report 00 - 4008

Figure 2. (A) Bedrock aquifers of the Great lakes Basin (modified from Great Lakes Commission, 1975); (B) Approximate extent of the freshwater bearing carbonate aquifer in Ohio, Indiana, Illinois, and parts of Michigan and Wisconsin (modified from Casey, 1996, figure 14);(C) Approximate extent of the sandstone aquifer west of Lake Michigan (modified from Young, 1992, figure 16).