For over 100 years, the U.S. Army Corps of Engineers has been tracking water levels across the Great Lakes basin. This data reveals that water levels in the Great Lakes cycle through high and low periods with each phase typically lasting several years. Water levels are primarily affected by precipitation, evaporation, and runoff. While Great Lakes water levels have always been dynamic and variable, climate change is resulting in faster shifts between low- and high-water years and more extreme highs and lows.

In 2020, Lake Michigan water levels rivaled the record highs set in 1986 and in 2013 Lake Michigan experienced the lowest water level on record. The changing climate has caused more intense storms and rain events resulting in severe shoreline flooding, inundated septic fields, flooded basements, and highly erosive wave and ice action during high water periods. These weather-related events are affecting property owners on the Great Lakes, inland lakes, and rivers across the state and pose a threat to water quality and public health. During periods of low water, navigation, commercial fishing, and shipping may be affected. Further, low water periods pose challenges for hydropower facilities and drowning water filtration plants that may need to invest in new infrastructure.