This is the only source that brings together comparable information from all Great Lakes and St. Lawrence River jurisdictions. It is difficult to compare water usage between jurisdictions because there are inconsistencies in how different jurisdictions gather data. Michigan's reporting system is still incomplete. Despite these weaknesses, the Annual Report provides the only reasonably comprehensive information available. The surface waters of the Great Lakes Basin are the source of drinking water for approximately 80 percent of the residents of the Great Lakes Basin.
Surface waters are also critical for recreational and navigational purposes.
Groundwater is the primary source of water for self-supplied residential, industrial and commercial uses. Approximately 21 percent of the residents of the Basin depend on groundwater for drinking either from self-supplied systems or municipal water supply systems. 5 Groundwater is the primary source for irrigation and livestock watering. Because the economies, industries, and geographies of Basin jurisdictions differ, each Great Lakes state and province has its own pattern of water usage. However, some generalizations can be made.