Lake Ontario Overview


Lake Ontario is the 14th largest lake in the world and the smallest of the North American Great Lakes by surface area (it is fourth in maximum depth second only to Lake Superior).  Lake Ontario has a draining basin area of 24,720 sq. miles (64,030 sq km) and is bounded by New York, Ontario and Pennsylvania.  The majority of the area in the basin is rural featuring many scenic resorts and parks with a few larger metropolitan areas including Toronto, Ontario and Rochester, New York.  The population of Lake Ontario is 8,150,895 (2,704,284 U.S. and 5,446,611 Canadian).

Lake Ontario is located 325 ft (99 m) below Lake Erie at the base of Niagara Falls. Before the construction of the Trent-Severn Waterway and Welland (1913) and Erie Canals, the falls posed a major obstacle to Great Lakes navigation. Lake Ontario supports many wetlands and an important freshwater fishery. Major tributaries into Lake Ontario include the Niagara, Trent, Oswego and Salmon Rivers.  The primary outflow is the St. Lawrence River. 


Surface Area 7,340 miles2 18,960 km2
Maximum Depth 802 ft 244 m
Watershed Area 24,722 miles2 64,030 km2
# of Fish Species 106*  
Water Retention/Replacement Time 6 years  

*95 native, 11 introduced


Lake Ontario

aCoordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data, Coordinated Great Lakes Physical Data. May, 1992


Links to other resources:

Great Lakes Atlas - U.S. EPA