Lake Ontario Facts


Lake Ontario is the easternmost Great Lake. It’s surrounded by New York and the Canadian province of Ontario. Water flows out out Lake Ontario through the St. Lawrence River on its way to the Atlantic Ocean.

Lake Ontario Basin Statistics
  • Length: 193 mi (311 km)
  • Breadth: 53 mi (85 km)
  • Elevation: 243.3 ft (74.2 m)
  • Depth: 283 ft (86 m average); 802 ft (244 m) maximum
  • Volume: 393 cubic mi (1,639 cubic km)
  • Water surface area: 7,340 square mi (19,009 square km)
  • Drainage basin area: 23,400 square mi (60,601 square km)
  • Shoreline length: 712 mi (1,146 km), including islands
  • Outlet: St. Lawrence River to the Atlantic Ocean
  • Retention or replacement time: 6 years
  • U.S. population: 2.8 million
  • Canada population: 2.8 million
Lake Ontario Basin

Lake Ontario Basin

Source:Michigan Sea Grant.