ONTARIO, LAKE, the smallest and most easterly of the Great Lakes of North America, is bounded on the north by the Province of Ontario and on the south by the State of New York. It is roughly elliptical, its major axis, 18o m. long, lies nearly east and west, and its greatest breadth is 53 miles. The area of its water surface is 7,540 sq.m. and the total area of its basin 34,63o sq. miles. Its greatest depth is 738 ft., its average depth much in excess of that of Lake Erie, and it is, as a general rule, free from outlying shoals or dangers.
On the north side of the lake the land rises gradually from the shore, and spreads out into broad plains, which are thickly settled by farmers. A marked feature of the topog raphy of the south shore is what is known as the Lake ridge, or, as it approaches the Niagara river, the Mountain ridge. This ridge extends, with breaks, from Sodus to the Niagara river, and is distant from the lake 3 to 8 miles. The low ground between it and the shore is a celebrated fruit-growing district, covered with vineyards, peach, apple and pear orchards and fruit farms. The Niagara river is the main feeder of the lake ; the other largest rivers emptying into the lake are the Genesee, Oswego and Black from the south side, and the Trent, which discharges into the upper end of the bay of Quinte, a picturesque inlet 7o m. long, on the north shore, between the peninsula of Prince Edward, near the eastern extremity of the lake, and the mainland. The east end of the lake, where it is 3o m. wide, is crossed by a chain of five islands, and the lake has its outlet near Kingston, where it dis charges into the head of the St. Lawrence river between a group of islands. Elsewhere the lake is practically free from islands. There is a general surface current down the lake towards the east ward of about 8 m. a day, strongest along the south shore, but no noticeable return current. As a result of its relatively great depth there are seldom any great fluctuations of level in this lake due to wind disturbance, but the lake follows the general rule of the Great Lakes of seasonal and annual variation. Its mean surface elevation above mean sea-level, for a period of 68 years, is 246.09 ft., which is some 326.33 ft. below the level of Lake Erie. The lake never freezes over except near land, but the harbours are closed by ice from about mid-December to mid-April.
Ports.—The principal Canadian ports are Kingston, at the head of the St. Lawrence river; Toronto, where the harbour is formed by an island with improved entrance channels constructed both east and west of it; and Hamilton, at the head of the lake, situ ated on a land-locked lagoon, connected with the main lake by Burlington channel, an artificial cut. The principal U.S. port is Oswego, where a breakwater has been built, making an outer harbour.
The commerce of Lake Ontario is limited in com parison with that of the lakes above Niagara Falls, and is in general confined to vessels which can pass the Welland canal and the St. Lawrence canals ; the harbours on the lake are planned to
accommodate vessels limited to the size determined by the dimensions of the smallest locks, which are : length 27o ft., width 45 ft. and depth 14 ft. on sills. The commerce on the lake is generally confined to coal shipped from Rochester, Sodus bay, Little Sodus bay and Oswego to Canadian ports on the lake and U.S. and Canadian ports on the St. Lawrence river; to coal from Oswego to upper lake ports; to grain and other products shipped from upper lake ports through the Welland canal to the St. Lawrence ; to lumber from Canadian ports; and to pleasure traffic.
The completion, about 193o, of the New Welland canal by the Canadian Government (see NIAGARA RIVER) will permit the large lake vessels now operating on the upper Great Lakes to enter Lake Ontario. Negotiations under way in 1928 between the United States and the Canadian Governments will undoubtedly result in the improvement of the St. Lawrence river for power and navigation, thereby providing a navigable channel to the sea, suitable for ocean-going vessels. For a century, the Erie and Oswego canals, built and operated by the State of New York, have been important water outlets from Lake Erie and Lake Ontario to the Hudson river and to New York city. The present canal is 12 ft. deep and is designed for use by boats drawing '01 feet. The canal distance from Oswego to New York city is 338 miles. The Murray canal extends from Presqu'ile bay, on the north of the lake, to the head of the bay of Quinte, and enables vessels to avoid 7o m. of open navigation. It is II ft. deep below the lowest lake level and has no locks.
Trent canal is the term applied to a series of rivers and lakes connected by short canals, designed to form a continuous system of light-draught navigation between Lake Ontario and Georgian bay, Lake Huron. Six-foot navigation is now available for 224 m. from Lake Ontario to Swift Rapids on the Severn river and, upon completion of the Severn division at the Georgian bay end, will be possible for the entire route. Even now facilities are provided whereby small motor boats proceed through from Lake Ontario to Lake Huron. At Kingston the Rideau canal, extending 128 m. to Ottawa, enters the St. Lawrence river at the foot of the lake. This canal has 47 locks, with minimum dimensions of 134 ft. by 33 ft., and a depth of 5 feet.
No. 37, Survey of Northern and North western Lakes (Detroit, April 1928) ; Annual Report of Chief of Engineers, U.S. army, U.S. Government Printing Office (1927) ; The St. Lawrence Waterway, report of Joint Board of Engineers appointed by the Governments of the United States and Canada, U.S. Govern ment Printing Office (1927). (E. JA.)