Thompson River is the largest tributary of the Fraser River,
flowing through the south-central portion of British Columbia, Canada.
Thompson River has two main branches, the
South Thompson River
South Thompson River and
the North Thompson River. The river is home to several varieties of
Pacific salmon and trout. The area's geological history was heavily
influenced by glaciation, and the several large glacial lakes have
filled the river valley over the last 12,000 years. Archaeological
evidence shows human habitation in the watershed dating back to at
least 8300 years. The Thompson was named by
Fraser River explorer,
Simon Fraser, in honour of his friend, Columbia Basin explorer David
Thompson. Recreational use of the river includes whitewater rafting
1.1 South Thompson River
1.2 North Thompson River
2.1 Glacial lakes
3.1 Aboriginal peoples
3.2 European exploration and settlement
5 Conservation and recreation
5.2 Whitewater rafting
6 Major Tributaries
6.1 North Thompson River
6.2 South Thompson River
7 See also
10 External links
South Thompson River
The South Thompson originates at the outlet of
Little Shuswap Lake at
the town of Chase and flows approximately 55 kilometres (34 mi)
southwest through a wide valley to
Kamloops where it joins the North
Thompson. Highway 1, the Trans-
Canada Highway and the mainline of the
Canadian Pacific Railway
Canadian Pacific Railway parallel the river.
Little Shuswap Lake is
fed by the Little River, which drains Shuswap Lake, which is fed by
several rivers & creeks.
North Thompson River
The North Thompson originates at the toe of the Thompson Glacier in
Cariboo Mountains west of the community of Valemount and flows
generally south towards
Kamloops and the confluence with the South
Thompson. For most of its length, the river is paralleled by Highway
5, and the
Canadian National Railway
Canadian National Railway (both of which cross the river a
couple times). The North Thompson passes by several small communities,
the most notable being Blue River, Clearwater & Barriere.
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.
The darker waters of the Thompson meet the Fraser at Lytton.
At Kamloops, the combined
Thompson River 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
Canada Highway, the
Canadian Pacific Railway
Canadian Pacific Railway and the Canadian
From Ashcroft to Lytton, the river is completely confined within
Thompson Canyon, making for spectacular scenery. The Thompson River
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.
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. 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. This flow
direction is estimated to have ended approximately 2 million years
ago, as the
Pleistocene era of heavy glaciation began.
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. 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
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.
Because of large deposits of glacial silt, sand, and gravel in the
Thompson River valley, large landslides are common. 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
Remnants of a landslide near the railway in the lower Thompson River
The Interior region of
British Columbia was first populated after the
retreat of the continental ice sheets of the last ice age. The ice
moved out of the
Thompson River region approximately 11,000 BCE, and
migration by the ancestors of the
Secwepemc people is
thought to have occurred soon after. Some of the older
archaeological sites on the lower Thompson include the Drynoch Slide
site, near Spences Bridge, with artifacts dating to about 7350 BCE,
and the Landels site, near Ashcroft, which dates to older than 8000
BCE. Archaeologists theorize early settlers lived in small groups,
beginning with nomadic bands hunting ungulates on the plateaus around
the river, who then established more permanent dwellings along the
river benches as their fishing techniques developed.
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. 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.
European exploration and settlement
Explorer of the
Fraser River and
North West Company
North West Company employee Simon
Fraser named the river, after passing its mouth on the Fraser in
1808. He named the river after his colleague, David Thompson, who
had mapped much of western
Canada and was at the time exploring the
Columbia River basin to the east. Thompson never visited the river
that bears his name. The first documented traverse of the Thompson
Kamloops to Lytton was by
Hudson's Bay Company
Hudson's Bay Company governor George
Simpson in 1828. More Europeans entered the
Thompson River valley
in the early to mid 1800s, drawn by the fur trade and small gold
rushes. Others started farming on the fertile benches of the river,
North West Company
North West Company trading fort at the confluence of the North
and South rivers became the city of Kamloops, now the largest human
population center in the watershed.
Sockeye salmon during the salmon run, Roderick Haig-Brown Provincial
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
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
Several bird species are found in
Thompson River environments,
including osprey, merganser, wood ducks, and dippers. Golden eagles
are found near the confluence with the Fraser, 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.
Conservation and recreation
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. Under the
British Columbia Fish Protection Act
of 1997, the Thompson cannot be considered for future dam
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.
Hwy 5 bridge, first crossing of N.
Thompson River after emerging from
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. 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). 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.
The river is subject to catch and release angling only for steelhead
and has severely restricted seasons to protect the wild stocks of
The rapids of the lower Thompson are used for recreational whitewater
rafting. The first commercial rafting operation on the river began in
the 1970s, based out of Spences Bridge. Notable whitewater
features on the lower river include the Frog, named for a frog-shaped
rock formation, and the Jaws of Death, named by CPR engineers.
Rapids on the river reach up to Class 5 on the International Scale of
North Thompson River
South Thompson River
Little River (via
Little Shuswap Lake from Shuswap Lake)
Tranquille River (via
Oregon Jack Creek
List of tributaries of the Fraser River
British Columbia rivers
List of crossings of the Thompson River
^ "Thompson River". BC Geographical Names.
^ Thompson River, The Columbia Gazetteer of North America
^ a b Thompson River, BritishColumbia.com
^ "Thompson Glacier". BC Geographical Names.
^ a b Fandritch 2013, p. 270.
^ a b Fandritch 2013, p. 271.
^ a b Johnsen, Timothy F.; Brennand, Tracy A. (2004). "Late-glacial
lakes in the Thompson Basin, British Columbia: paleogeography and
evolution" (PDF). Canadian Journal of Earth Sciences. National
Research Council (Canada). doi:10.1139/E04-074.
^ a b Clague, John J. (August 1, 2003). "Geologic Framework of Large
Historic Landslides in
Thompson River Valley, British Columbia".
Environmental & Engineering Geoscience. 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.
^ Fandritch 2013, p. 7.
^ a b Benke & Cushing 2005, p. 710.
^ Benke & Cushing 2005, p. 725.
^ Fandritch 2013, p. 284.
^ "BILL 25 -- 1997: FISH PROTECTION ACT". www.env.gov.bc.ca. Retrieved
^ Combs, Trey (1999). "Thompson River". Steelhead Fly Fishing.
Heritage House Publishing Co. pp. 218–228.
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,
^ "Changes to
Thompson River steelhead management". BC Gov
News-Ministry of Forests, Lands and Natural Resource Operations. July
8, 2014. Retrieved December 5, 2016.
^ Fandritch 2013, p. 186.
Rousseau, Mike (Autumn 1993). "Early Prehistoric Occupation of
South-Central British Columbia". BC Studies. University of British
Columbia. 99. ISSN 0005-2949.
Benke, Arthur C.; Cushing, Colbert E. (2005). Rivers of North America.
Boston: Elsevier. ISBN 9780120882533.
Fandritch, Bernard (2013). British Columbia's Majestic Thompson River:
Km-by-km Guide, Events, and Tales. Lytton, BC: Nicoamen House.
Media related to
Thompson River at Wikimedia Commons
Hydrography of British Columbia
Gulf of Georgia
Queen Charlotte Sound