Great Lakes St. Lawence Regional Body/Compact Council Cumulative Impact Assessment Released

While higher-highs and lower-lows are expected to come more frequently, the overall amount of water in the Great Lakes-St. Lawrence system are unlikely to be significantly different than historical long-term averages, despite any water balance components that may have been impacted by climate change, according to a newly released study by the Great Lakes St. Lawrence Compact Council and Regional Body. 

“Our findings suggest that over the next several decades, we may see greater fluctuation levels in the Great Lakes-St. Lawrence, but the overall water level is projected to remain on par with historical averages,” Dr. Andrew Gronewold, associate professor at the University of Michigan and the study’s principal investigator said. “We do find that both precipitation and evaporation are likely to increase over the coming decades, leading to a wetter and hotter climate in the region.” 

Every five years a Cumulative Impact Assessment study is required by the Agreement and Compact between States and Provinces that are members of the Great Lakes-St Lawrence River Water Resources Regional Body and the Great Lakes-St. Lawrence River Basin Water Resources Council. For the most recent study, 2016-2020, projected climate models were included, in addition to projected trends.

“Being able to plan for the future is important to each of the Great Lakes-St. Lawrence States and Provinces,” said Wisconsin Department of Natural Resources Secretary Adam N. Payne.  “These are critical tools that allow us to work together to protect 20% of the world’s fresh surface water. Knowing what we are likely to face in the future will help us protect this unique heritage we all share.”

The assessment also presents the impact of human use on water budgets for the entire Basin and for each of the individual Watersheds. These include the watersheds for Lake Superior, Lakes Michigan-Huron, Lake Erie, Lake Ontario, and the St. Lawrence River.

To read the full Cumulative Impact Report, please download here.

The Regional Body includes the eight Great Lakes-St. Lawrence Governors of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin and the Premiers of Ontario and Québec. The Compact Council includes the eight Great Lakes Governors. They work closely with one another to sustainably manage the region’s shared waters. The Conference of Great Lakes and St. Lawrence Governors and Premiers serves as Secretariat to both the Regional Body and Compact Council.