There are many factors that influence the water levels of Lake Michigan and the other Great Lakes. The primary influence is the water balance which is water entering the lakes and the water leaving the lakes. Water entering the lakes comes from precipitation - rain, snow and runoff from rivers, land and connecting channels between the lakes and groundwater inflow. Water leaves the lake through the connecting channels, groundwater outflow and evaporation. With the reduced ice cover on the Lakes during the winter, there is increasing amounts of evaporative loss. This compounded with the reduced inputs from rain and snow due to continual drought conditions in the Great Lakes basin over the last 10+ years has significantly reduced the amount of water to the lakes. The economic impact of water levels on commercial shipping, harbors, marinas, tourism, recreational boating, and other uses of the Great Lakes are discussed.