What Are The Primary Inflows And Outflows Of Lake Ontario?

The city of Toronto on the shores of Lake Ontario.

Lake Ontario in North America is one of the five Great Lakes which constitute the largest group of lakes on earth. Lake Ontario sits on the border of two countries forming the boundary between the Candian province of Ontario and the US state of New York. Lake Ontario was formed as a result of glacial action. The depths of the lake which go up to 802 feet in some parts ensures that, unlike some of the other Great Lakes, it never completely freezes over in the winter. The primary inlet of Lake Ontario is the Niagara River which originates from Lake Erie while the lake’s primary outflow is the Saint Lawrence River.

The Niagara River

The Niagara River is the source of Lake Ontario’s waters. The Niagara’s tributaries are the Tonawanda Creek and the Welland River. It flows from the northern part of Lake Erie and empties into Lake Ontario and forms a natural border between the Canadian province of Ontario and New York in the US. The Niagara River is about 36 miles in length and the famous Niagara Falls is along its course. Many parts along the river’s course are utilized for production of hydroelectricity they include Sir Adam Beck and the Robert Moses stations. Of historical significance is the fact that the Niagara River was the site of the earliest railway in American history, a wooden tramway line built between 1736 and 1799.

Saint Lawrence River

Saint Lawrence River is a big river in North America and serves as the primary outflow of Lake Ontario as well as being the main drainage body for the larger Great Lakes basin. It generally flows towards the northeast and is the main water body that connects the Great Lakes basin to the Atlantic Ocean. The river begins its course at the outflow of Lake Ontario as it cuts through Quebec and Ontario both in Canada as well as forming a boundary between Ontario and New York like the Niagara River. The Saint Lawrence River runs about 310 miles in length with a basin size of approximately 519,000 square miles. 


The Great Lakes region as a whole is home to a large number of plant and animal life, Lake Ontario is an important region in this diversity. It is home to a large number of birds, reptiles, and fish. A large percentage of these species live on the shoreline in lagoons and wetlands which has led to government recognition of these wetlands and the important natural habitat they protect. These wetlands, however, continue to face the threat of annihilation since natural water levels continue to drop and measures should be put in place to support these areas.


More in Environment