What dam regulates Lake Ontario’s outflow into the St. Lawrence River?

The Moses-Saunders Power Dam regulates Lake Ontario’s outflow into the St. Lawrence River.

The dam sits near Massena, New York, and Cornwall, Ontario, where it forms the Moses-Saunders Reservoir. It began operating in 1958 and is jointly managed by the New York Power Authority and Ontario Power Generation. The project produces hydroelectricity while helping control downstream water levels and flows.

Lake Ontario is the lowest and most easterly Great Lake. Its natural outlet is the St. Lawrence River, which carries Great Lakes water toward Montreal and eventually the Atlantic Ocean. Because the lake is connected to a major navigation route and densely settled shoreline, regulating flow has important effects on shipping, flooding, shoreline erosion, and power generation.

The dam is often confused with the Welland Canal, which bypasses Niagara Falls between Lake Erie and Lake Ontario. The dam does not connect two Great Lakes; it controls the flow leaving Lake Ontario.