Smallest of the Great Lakes in surface area, Lake Ontario is still the 14th largest freshwater lake in the world.
Lake Ontario is the most easterly of the five Great Lakes. Lying 99 metres below Lake Erie, water thunders down at Niagara Falls and enters the lake from the Niagara River, emptying into the St. Lawrence River in the east.
Niagara Falls also forms an impassable barrier for fish. As a result, Lake Ontario is the only Great Lake to host unique fish species such as Atlantic Salmon and American Eel.
Lake Ontario ranks fourth among the Great Lakes in maximum depth, but its average depth is second only to Lake Superior. It takes six years to replenish the water in Lake Ontario. Because it is so deep, Lake Ontario rarely freezes over completely in winter. The only two recorded times this happened were the winter of 1874–75 and in February 1934.
Close to 9 million people live within the watershed of Lake Ontario. That means millions of Ontarians depend on the lake for their drinking water and for the many benefits the lake provides, such as power, transportation, agriculture and recreation.
Challenges: pollution, invasive species and a growing population
Because all the Great Lakes drain through Lake Ontario, it has been impacted the most by the accumulation of harmful pollutants — for example, in 1976, high levels of Mirex and PCBs were reported having leached from the toxic waste dumps on the Niagara River. Work is ongoing to clean up areas of historic pollution around the lake such as Hamilton Harbour.
Invasive zebra and quagga mussels have affected the health of the lake’s ecosystem. Lake Ontario is now able to grow fewer sport fish and more of the nuisance algae that foul beaches and clog water intakes.
The Lake Ontario Basin is home to 56 per cent of Ontario’s population and the growing cities that make up the Greater Toronto Area and Golden Horseshoe.
An additional 3.7 million people are expected to come here by 2013, a 43 per cent increase. With population growth comes an increased need for water, for power and for the infrastructure that supports communities.
Today, more people are recognizing the importance of Lake Ontario and are getting involved in actions to protect the lake and help restore it to a healthy state.
You can help Lake Ontario by: