How is the water level of Lake Ontario and the upper St. Lawrence River controlled?
Historically, Lake Ontario water levels change in 30-year cycles, with fluctuations as much of nearly seven feet, according to Frank Bevacqua, a spokesman for the International Joint Commission, a panel with representatives from both counties that resolve conflicts over the use of shared waters.
That changed with the construction in the 1950s of the Moses-Saunders Power Dam on the St. Lawrence River, which straddles the border between the United States and Canada at Massena in New York and Cornwall in Ontario. Constructed lasted between 1954 and 1958. The dam is part of a larger project called the St. Lawrence Seaway.