Water Levels & Diversions

  • Great Lakes ResourcesLake levels are determined by the combined influence of precipitation (the primary source of natural water supply to the Great Lakes), upstream inflows, groundwater, surface water runoff, evaporation, diversions into and out of the system, consumptive uses, dredging and water level regulation. The interplay between human activities, such as dredging, consumptive uses, in and out of basin diversions, wetland reduction, urbanization and agriculture, and the ecology of the lakes is highly complex.