Drainage

Overview
Physiography | Geology | Tectonics | Soils | Drainage | Vegetation

British Columbia is drained by six major rivers - Fraser, Columbia, Peace, Skeena, Stikine and Liard. In addition, a large number of short rivers drain west to the Pacific Ocean from the Coast Mountains, and a few others drain Vancouver Island and the Queen Charlotte Islands.

The Fraser River Drainage Basin has an area of roughly 233,000 square kilometres. At the mouth, its estimated mean annual discharge is about 3800 cubic metres per second. To date only two of the Fraserís tributaries have been dammed - the Bridge River and the Nechako River. In the case of the Nechako River, its headwaters in Tweedsmuir Park have been diverted to the Pacific slope through the Kemano tunnel.

The most devastating floods on the Fraser River took place in 1894 and in 1948. In addition, on February 23, 1914, a rockslide cut the flow of the Fraser River to a trickle at Hellís Gate. The slide was largely the result of work to build the Canadian Northern Railway.

The Columbia River Basin, just under half the size of the Fraser Basin at 102,000 square kilometres, has a discharge of 2193 cubic metres per second. The Columbiaís main tributaries are the Kootenay, Similkameen and Okanagan Rivers, each of which has some portion of its route in the United States.

Perhaps the most significant event to affect this river has been the Columbia Valley Treaty signed in the 1960s. This treaty allowed the construction of major dams on the Columbia River and its tributaries on both sides of the border.

The Peace River Drainage Basin, with an area of 128,000 square kilometres and a discharge of 1560 cubic metres per second, is formed by the conjunction of the Finlay and Parsnip Rivers. The flow of the Peace River is considerably controlled now due to the construction of the W. A. C. Bennett Dam.

The Liard River Basin is located in the provinceís far north eastern corner, with an area of 144,000 square kilometres and a mean annual discharge of about 1380 cubic metres per second. Partly because of its distance from major urban centres, little is known or understood about this river.

The Stikine River flows west into the Pacific Ocean and drains an area of roughly 51,000 square kilometres and has an estimated discharge of 1350 cubic metres per second. Surveys in the late 1960s indicated this river held a number of potential hydro electric dam sites.

Just south of the Stikine is the Skeena River Drainage Basin. With a drainage area of roughly 54,000 square kilometres and an estimated discharge of 1730 cubic metres per second, it is the provinceís second most important salmon river after the Fraser. One of the riverís unique qualities is the softness of its water. This is due to the fact that creeks and rivers emptying into the Skeena are short; therefore, their water has had little opportunity to pick up soluble minerals.

Any study of British Columbiaís rivers quickly reveals several issues for consideration. Foremost on this list is the lack of data. There are few locations where river data have been gathered, and the few that do exist offer a very short record of reliable information. Equally important are the pressures on this renewable resource as population grows, industry expands, wilderness access increases, and traditional land uses are altered. Nevertheless, the resource remains a spectacular component of the provinceís landscape.

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