Ground-Water Flow to the Great Lakes

Understanding the interaction of ground water and surface water in the Great Lakes basin is essential. In many ways, the two are so closely linked that they must be thought of as a single resource. Wise management of water resources in the Great Lakes requires an understanding that ground water is a large component of the Great Lakes water budget. The main ground-water resources issues in the Great Lakes Region are related to the amount of ground water, the interaction of ground water and surface water, changes in ground-water quality as development expands, and ecosystem health related to quantity and quality of water.

On average, 67 percent of the streamflow for 195 streams in the United States part of the Great Lakes Basin comes from ground water. Incorporation of these estimates into the basin water supply for the Great Lakes shows that indirect discharge of ground water to the Great Lakes ranges from 22 percent of the basin water supply of Lake Erie to 42 percent of the basin water supply for Lake Ontario.

In addition, ground water is the source of drinking water for millions of people in the region, is an important source of supply for agriculture and many industries, and provides a relatively uniform supply of water in some ecologically sensitive areas to sustain plant and animal species.

Indirect Ground-Water Discharge to the Great Lakes

The Importance of Ground Water in the Great Lakes Region