Lake Ontario

Lake Ontario
Looking east across Lake Ontario to Toronto
Lake Ontario and the other Great Lakes
Location	North America
Group	Great Lakes
Coordinates	43°42′N 77°54′W / 43.7°N 77.9°W / 43.7; -77.9Coordinates: 43°42′N 77°54′W / 43.7°N 77.9°W / 43.7; -77.9
Lake type	Glacial
Primary inflows	Niagara River
Primary outflows	St. Lawrence River
Catchment area	24,720 sq mi (64,000 km2)
Basin countries	United States Canada
Max. length	193 mi (311 km)
Max. width	53 mi (85 km)
Surface area	7,340 sq mi (19,000 km2)
Average depth	283 ft (86 m)
Max. depth	802 ft (244 m)
Water volume	393 cu mi (1,640 km3)
Residence time	6 years
Shore length1	634 mi (1,020 km) plus 78 mi (126 km) for islands
Surface elevation	243 ft (74 m)
Settlements	Toronto, Ontario Hamilton, Ontario Rochester, New York
References
1 Shore length is not a well-defined measure.

Lake Ontario (French: Lac Ontario) is one of the five Great Lakes of North America. It is surrounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the American state of New York, whose water boundaries meet in the middle of the lake. Ontario, Canada's most populous province, was named for the lake. In the Wyandot (Huron) language, ontarío means “Lake of Shining Waters”. Its primary inlet is the Niagara River from Lake Erie. The last in the Great Lakes chain, Lake Ontario serves as the outlet to the Atlantic Ocean via the St. Lawrence River.

Lake Ontario is the easternmost of the Great Lakes and the smallest in surface area (7,340 sq mi, 18,960 km²), although it exceeds Lake Erie in volume (393 cu mi, 1,639 km³). It is the 14th largest lake in the world. When its islands are included, the lake has a shoreline that is 712 miles (1,146 km) long. As the last lake in the Great Lakes' hydrologic chain, Lake Ontario has the lowest mean surface elevation of the lakes at 243 feet (74 m) above sea level; 326 feet (99 m) lower than its neighbor upstream. Its maximum length is 193 statute miles (311 kilometres; 168 nautical miles) and its maximum width is 53 statute miles (85 km; 46 nmi). The lake's average depth is 47 fathoms 1 foot (283 ft; 86 m), with a maximum depth of 133 fathoms 4 feet (802 ft; 244 m). The lake's primary source is the Niagara River, draining Lake Erie, with the St. Lawrence River serving as the outlet. The drainage basin covers 24,720 square miles (64,030 km²). As with all the Great Lakes, water levels change both within the year (owing to seasonal changes in water input) and among years (owing to longer term trends in precipitation). These water level fluctuations are an integral part of lake ecology, and produce and maintain extensive wetlands. The lake also has an important freshwater fishery, although it has been negatively affected by factors including over-fishing, water pollution and invasive species.