The Eastern Dolomite Aquifer

The eastern dolomite (bedrock) aquifer exists along the easternmost part of Wisconsin from Door County south to near the Illinois border. This formation has the following characteristics:

• It was formed 400 million years ago
• It is a narrow strip of Niagara dolomite which exists above Maquoketa shale
• It is susceptible to contaminants in areas where the dolomite bedrock exists at or near the surface

The amount of water that can be obtained from a well drilled into this formation is largely dependent on the size of cracks and crevasses it intersects.