The Moses-Saunders Power Dam, short for Robert Moses-Robert H. Saunders Power Dam, is a dam on the Saint Lawrence River straddling the border between the United States and Canada. It is located between Massena in New York and Cornwall in Ontario. The dam supplies water to two adjacent hydroelectric power generating stations, the United States' 912 MW St. Lawrence-Franklin D. Roosevelt Power Project, and Canada's 1,045 MW R.H. Saunders Generating Station. Constructed between 1954 and 1958 as part of the larger Saint Lawrence Seaway project, the dam created Lake St. Lawrence. Aside from providing significant amounts of renewable power, the dam regulates the St. Lawrence River and affords passage for the navigation of large vessels. Despite the enormous economic advantages of the dam, it required the relocation of 6,500 people and caused harm to the surrounding environment. Efforts have been made over the years to improve shoreline and fish habitats.
The dam regulates the level of Lake Ontario.