Given the diverse interests and needs along Lake Ontario and the St. Lawrence River, regulating water levels is a complex task.
In 1909, as part of the Boundary Waters Treaty, the International Joint Commission was established to help manage the shared waters along the Canadian-U.S. border. During the 1950's, the IJC approved the construction and operation of a hydropower project in the international section of the St. Lawrence River for the purpose of producing hydroelectricity, enabling seaway navigation and providing some flood protection to Lake Ontario and the St. Lawrence River. Flows through the Moses-Saunders Dam would also be regulated so that the lower St. Lawrence River received no less protection than with unregulated flows. Under the treaty, the IJC is tasked with ensuring that all affected interests are considered in decisions that change the levels and flows of boundary waters.