How much ground water is pumped in the Great Lakes Region?
Total ground-water withdrawal in the Great Lakes Region is estimated to be about 1,510 Mgal/d or 2,336 ft3/s (Solley and others, 1998). An additional 200 Mgal/d or 309 ft3/s is withdrawn from outside the basin but near Lake Michigan in the Chicago area to supply commercial, industrial, domestic, and public-supply customers. For comparison, the average discharge of the St. Clair River at Port Huron is about 120,850 Mgal/d or 187,000 ft3/s. On a basinwide scale, ground-water withdrawal is a small part of the overall hydrologic budget and only about 5 percent of this water is consumed. The remainder is returned mostly as surface water effluent. Nevertheless, ground water is the source of drinking water for more than 8 million people on the U.S. side of the border in the basin (about one third of the total number of residents) and continues to be a concern in both the U.S. and Canada. The areas where large quantities of ground water are pumped on the U.S. side of the Great Lakes watershed
