Thompson River
Thompson River | |
---|---|
Location | |
Country | Canada |
Province | British Columbia |
Land District | Kamloops Division Yale |
Physical characteristics | |
Source | Confluence of the North & South Thompson Rivers |
• location | Kamloops |
• coordinates | 50°40′49″N 120°20′36″W / 50.68028°N 120.34333°W |
• elevation | 345 m (1,132 ft) |
Mouth | Fraser River |
• location | Lytton |
• coordinates | 50°14′07″N 121°35′00″W / 50.23528°N 121.58333°W[1] |
• elevation | 195 m (640 ft) |
Length | 489 km (304 mi)[2] |
Basin size | 56,000 km2 (22,000 sq mi)[3] |
Discharge | |
• location | Spences Bridge |
• average | 773 m3/s (27,300 cu ft/s) |
• minimum | 171 m3/s (6,000 cu ft/s) |
• maximum | 4,200 m3/s (150,000 cu ft/s) |
The Thompson River is the largest
Geography
South Thompson River
The South Thompson originates at the outlet of
North Thompson River
The North Thompson originates at the toe of the Thompson Glacier
The North Thompson picks up the Clearwater River at the town of Clearwater. The Clearwater, the North Thompson's largest tributary, drains much of Wells Gray Provincial Park.
A notable feature along the North Thompson is Little Hells Gate, a mini-replica of the much larger rapid on the Fraser downstream from the mouth of the Thompson. About 17.4 kilometres (10.8 mi) upstream from the small town of Avola, the river is forced through a narrow chute only about 30 feet (9.1 m) wide creating a rapid that resembles the Fraser's famous rapid.
Mainstream
At Kamloops, the combined Thompson River flows 15 kilometres (9.3 mi) from the confluence of the North and South Thompson Rivers before reaching Kamloops Lake, which is roughly 30 kilometres (19 mi) in length, ending at the town of Savona. From there it flows in a meandering course westwards through a broad valley area. At Ashcroft, the Thompson Canyon begins and the river turns southwestward to its confluence with the Fraser. The river is paralleled by the Trans-Canada Highway, the Canadian Pacific Railway and the Canadian National Railway.
From Ashcroft to Lytton, the river is completely confined within Thompson Canyon, making for spectacular scenery. The Thompson River joins the Fraser River in Lytton. There is a striking stretch of dark black cliffside just downstream from Ashcroft and visible from the Logan Lake-Ashcroft highway is officially named the Black Canyon. Just below the town of Spences Bridge was the site of a major rail disaster in the early 20th century. Communities along this section are Bighorn, Shaw Springs, and Goldpan.
Geology
The Thompson River valley has existed in some form for at least 50 million years; however, for much of its history, it did not drain to the southwest into the Pacific Ocean as it does today.[5] Geologists believe water from the river flowed northward, through the Cariboo region, eventually entering what is the modern-day Peace River drainage basin and ending up in the Arctic Ocean.[6] This flow direction is estimated to have ended approximately 2 million years ago, as the Pleistocene era of heavy glaciation began.[6]
Glacial lakes
During the era of massive glaciers in the Thompson River valley, water from the area likely drained eastward, through the Shuswap Lake area into what is now the Columbia River drainage. This flow direction was influenced by large ice buildups in the Thompson valley, which created extensive glacial lakes. Two large glacial lakes, Glacial Lake Thompson and Glacial Lake Deadman, occupied much of the modern river's course from 13,000 BCE to 10,000 BCE. These deep, narrow, ribbon-shaped lakes held large volumes of water; Glacial Lake Thompson held nearly 84 cubic kilometres (20 cu mi) at its highest point. The lake stretched from Spences Bridge in the west to the eastern reaches of Shuswap Lake, as well as far up the northern reaches of the North Thompson river valley.[7] The last large glacial lake, Lake Deadman, was drained by a catastrophic ice dam failure, called a jökulhlaup, in about 10,000 BCE. This event released as much as 20 cubic kilometres (4.8 cu mi) of water southwest into the Fraser River system, possibly depositing sediments as far away as the Salish Sea, more than 250 kilometres (160 mi) away. From this point, the Thompson waters stopped flowing eastward into the Columbia River system, and the river became a tributary of the Fraser.[7]
Landslides
Because of large deposits of glacial silt, sand, and gravel in the lower Thompson River valley, large landslides are common.[8] The area downstream from the town of Ashcroft is prone to landslide events; eight major events between 1880 and 1982 have been recorded. Several of them have obstructed the river, and caused large, temporary lakes. An 1880 slide caused the formation of a short-lived lake over 14 kilometers long with a maximum depth of 18 meters. These slides have caused major damage to the rail lines and farming operations in the river valley. Heavy irrigation has been blamed for some of the events.[8]
History
Aboriginal peoples
The Interior region of British Columbia was first populated after the retreat of the continental ice sheets of the
The South Thompson has the watershed's oldest dated evidence of human habitation, at the Gore site near Pritchard. The human remains date to 8250 BCE, and bone analysis suggests the person was a hunter with small amounts of his protein coming from salmon.[12] Archaeological investigation in the North Thompson has been sparse, but artifacts near Bridge Lake to the west of the river have been dated to 3000 BCE, while pieces found near the tributary Clearwater River are possibly as old as 6000 to 7000 BCE.[12]
European exploration and settlement
Explorer of the Fraser River and
Ecology
The Thompson River supports 24 fish species, including two considered endangered. It also hosts carp, which are not native to the watershed. The river is home to large populations of Pacific salmon, including coho, sockeye, pink and chinook. Through its tributary, the Adams River, the Thompson has one of the largest sockeye salmon runs in the world.[15] Pink salmon spawn mostly below Kamloops Lake, while coho spawning beds are found in 40 of the Thompson watershed's streams and rivers. Coastal rainbow trout (Oncorhynchus mykiss irideus), including an anadromous variety called steelhead, are found in the river along with a local strain the Kamloops rainbow trout which occurs in Kamloops Lake at the Thompson River headwaters and other nearby lakes. Other fish species include round whitefish, largescale sucker, bridgelip sucker, northern pikeminnow, longnose dace, and slimy sculpin.[16]
Several bird species are found in Thompson River environments, including osprey, merganser, wood ducks, and American dippers. Golden eagles are found near the confluence with the Fraser,[17] and Bald eagles congregate on the river during the salmon run. Trumpeter swans use the South Thompson on their migratory route. Rattlesnakes are found in the dry sagebrush regions of the lower river. Aquatic insects found in the river system are dominated by three groups: mayflies, midges, and caddisflies. Many of these species emerge with the spring snowmelt, which greatly increases the volume of flow on the river.[15]
Conservation and recreation
The Thompson River and its two branches are mostly unprotected through parks or reserves. Small sections of the river are within provincial parks, including Steelhead, Juniper, Goldpan, and North Thompson Provincial Parks. Some of its tributaries, such as the Clearwater, are more protected through large parks like Wells Gray. However, unlike major river systems to the north and east like the Columbia and Nechako, the Thompson has no hydroelectric dams or major man-made water diversions.[13] Under the British Columbia Fish Protection Act of 1997, the Thompson cannot be considered for future dam construction.[18]
Conservation of the Thompson's fisheries, especially its salmon population, has been a focus of provincial, federal, and international bodies, such as the Department of Fisheries and Oceans (DFO) and the Pacific Salmon Commission.
Angling
From the 1950s through the early 1990s the Thompson River was considered one of the premier steelhead angling destinations in North America. The river hosted large runs of both summer and winter run anadromous coastal rainbow trout (Oncorhynchus mykiss irideus). In the late 1980s the runs were estimated at over 10,000 fish.[19] The river attracted anglers from around the world seeking powerful Thompson River steelhead. In 1982, the average male winter run Thompson River steelhead was 16 pounds (7.3 kg).[20] By the late 1990s, steelhead populations began to decline due to a wide variety of adverse environmental conditions and overfishing by commercial and First Nations gill netters. In 2016, annual steelhead numbers entering the Thompson were estimated to be less than 400 fish. Low numbers have prompted conservation organizations and sportsman's associations to petition Committee on the Status of Endangered Wildlife in Canada (COSEWIC), for Canada's Species At Risk Act (SARA) protections.[21] The river is subject to catch and release angling only for steelhead and has severely restricted seasons to protect the wild stocks of remaining steelhead.[22]
Whitewater rafting
The rapids of the lower Thompson are used for recreational
Major Tributaries
North Thompson River
- Albreda River
- Thunder River
- Mud Creek
- Blue River
- Mad River
- Raft River
- Clearwater River
- Barrière River
South Thompson River
- Little River (via Little Shuswap Lake from Shuswap Lake)
- Chase Creek
- Monte Creek
Mainstream
- Tranquille River (via Kamloops Lake)
- Deadman River
- Bonaparte River
- Oregon Jack Creek
- Nicola River
- Murray Creek
- Skoonka Creek
- Nicoamen River
- Botanie Creek
See also
- List of tributaries of the Fraser River
- List of rivers of British Columbia
- List of crossings of the Thompson River
Notes
- ^ "Thompson River". BC Geographical Names.
- ^ Thompson River Archived 2005-05-10 at the Wayback Machine, The Columbia Gazetteer of North America
- ^ a b Thompson River, BritishColumbia.com
- ^ "Thompson Glacier". BC Geographical Names.
- ^ a b Fandrich 2013, p. 270.
- ^ a b Fandrich 2013, p. 271.
- ^ doi:10.1139/E04-074.
- ^ doi:10.2113/9.3.201.
- ^ Rousseau 1993, p. 140.
- ^ Rousseau 1993, p. 153.
- ^ Rousseau 1993, p. 168.
- ^ a b Rousseau 1993, p. 156.
- ^ a b c d Benke & Cushing 2005, p. 708.
- ^ Fandrich 2013, p. 7.
- ^ a b Benke & Cushing 2005, p. 710.
- ^ Benke & Cushing 2005, p. 725.
- ^ Fandrich 2013, p. 284.
- ^ "BILL 25 -- 1997: FISH PROTECTION ACT". www.env.gov.bc.ca. Retrieved 2016-11-30.
- ISBN 9781895811728. Retrieved December 5, 2016.
- ^ Knap, Jerome J. (March 1982). "Fishing Across Canada". Field and Stream. LXXXVI (11): 138. Retrieved December 5, 2016.
- ^ Wedeking, Brett (March 18, 2016). "At Risk Status Sought for Thompson Steelhead". The Drake (drakemag.com). Retrieved December 5, 2016.
- ^ "Changes to Thompson River steelhead management". BC Gov News-Ministry of Forests, Lands and Natural Resource Operations. July 8, 2014. Retrieved December 5, 2016.
- ^ Fandrich 2013, p. 186.
References
- Rousseau, Mike (Autumn 1993). "Early Prehistoric Occupation of South-Central British Columbia". BC Studies. 99. University of British Columbia. ISSN 0005-2949.
- Benke, Arthur C.; Cushing, Colbert E. (2005). Rivers of North America. Boston: Elsevier. ISBN 9780120882533.
- Fandrich, Bernie (2013). British Columbia's Majestic Thompson River: Km-by-km Guide, Events, and Tales. Lytton, BC: Nicomen House. ISBN 9780991734504.
External links
- Media related to Thompson River at Wikimedia Commons