Lake Ontario drainage basin map

Lake Ontario is the last of the chain of Great Lakes that straddle the Canada/United States border. Its shoreline is bordered by the Province of Ontario on the Canadian side and New York State on the US side. Lake Ontario is the smallest of the Great Lakes, with a surface area of 18 960 square kilometres, but it has the highest ratio of watershed area to lake surface area.

Map: The Lake Ontario Drainage Basin

This map of the Lake Ontario drainage basin, which includes the St. Lawrence River drainage basin, shows a small inset showing the position of Lake Ontario relative to the other Great Lakes - it is the most eastern lake. The map, whose scale is in hundreds of kilometres and is oriented in the north direction, shows the Lake Ontario drainage basin on the left (west of the St. Lawrence River drainage basin), and the St. Lawrence drainage basin on the right (east of the Lake Ontario drainage basin), and all provinces, states, cities, Areas of Concern (AOC), and tributaries within them.

The Canadian provinces shown are Ontario and Qu├ębec. United States (US) state shown is New York. The international border between Canada and the US runs between the borders of Ontario and New York, through the middle of Lake Ontario, and along the St. Lawrence River. Canadian cities shown (all in Ontario): Cornwall, Kingston, Belleville, Peterborough, Oshawa, Toronto, Hamilton, St. Catharines, and Niagara Falls. US cities shown (all in New York): Niagara Falls, Rochester, Auburn, Syracuse, Watertown, and Massena.

Canadian AOCs shown in the Lake Ontario drainage basin: Hamilton Harbour, Toronto and Region, Port Hope, and Bay of Quinte. US AOCs shown in the Lake Ontario drainage basin: Eighteen Mile Creek, and Rochester Embayment. Delisted US AOC shown in the Lake Ontario drainage basin, which is an AOC remediated and removed from the list: Oswego River/Harbour. Binational AOCs shown, which are those AOCs that are shared by Canada and the US: Niagara River (in the Lake Ontario drainage basin), and St. Lawrence River (in the St. Lawrence River drainage basin).

Also shown on the map are tributaries. A tributary is a river or stream flowing into a larger river or lake. 5 unnamed tributaries to Lake Ontario are shown, with 2 along the northern coast of the lake in Ontario, 1 to the south-west coast in Ontario, and 2 along the south coast in the state of New York.

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