The IJC has the authority to regulate two points of control at the upper and lower ends of the Great Lakes system, the outflow of Lake Superior and Lake Ontario, according to Orders of Approval from the American and Canadian governments. While it was not the original reason for the construction of control structures on the Great Lakes, regulation using dams can mitigate the severity of extreme levels. The major deciding impacts on water levels in the Great Lakes are natural factors such as precipitation over the entire Great Lakes basin, supply from upper Great Lakes, and runoff from the drainage basin. The regulation of the two points of control is carefully balanced due to the different interests and constraining factors in the Great Lakes basin and areas around the dams. The other factors that influence water levels include diversions of water into and out of the system which are controlled by various authorities, urbanization and changes to the landscape, and consumptive uses by private citizens, municipalities, and industries.
Relevant Links
For Frequently Asked Questions and Answers regarding regulation Plan 2014 and the recent high water levels on Lake Ontario and the St. Lawrence River, please go to Plan 2014 Frequently Asked Questions
For more information on regulation in the upper Great Lakes, please go to Upper Great Lakes (still draft)
For more information on regulation in the Lake Ontario-St. Lawrence River basin, please go to Lake Ontario-St. Lawrence River (still draft)