Great Bear Lake, Northwest Territories, Canada

A place of historical events, Great Bear Lake remains one of the most untouched and pristine bodies of water of its size in the world.

The Great Lakes of North America are widely known as some of the largest inland bodies of water in the world. Canada and the United States share them equally, with the international border running down the middle of Lakes Huron, Michigan, Superior, Ontario and Erie. But over two thousand miles away, tucked into the upper reaches of the Northwest Territories, lies the largest freshwater lake contained entirely within Canada’s borders: Great Bear Lake.

Created 12,000 years ago when the retreat of Pleistocene-era glacial ice sheets left depressions in the northern tundra that later filled with water, Great Bear Lake has a surface area of over 31,000 square kilometers (12,000 square miles), making it roughly the same size as Belgium or the Netherlands. It is the fourth largest lake in North America and the eighth largest in the world. Slightly to the southeast lies Great Slave Lake–also part of the larger Mackenzie Basin–and while fractionally smaller, being only the tenth largest lake in the world by surface area, Great Slave Lake holds the title of deepest lake in North America at 614 meters (2,014 feet).

Among the world’s major lakes Great Bear Lake is the most northerly, with its northernmost arm protruding into the arctic circle. Summertime air temperatures hover in a temperate range of 18-20°C (65-68°F), while winter sees average temperatures of less than -25°C (-13°F). In winter the lake freezes to a depth of around two meters (nearly seven feet) and often does not fully thaw until early summer. As a result, even in summer the water in the main body of the lake barely reaches 4°C (39°F).

Viewed from above, the outline of Great Bear Lake resembles a crude jigsaw puzzle piece with five rough-hewn arms radiating out from the center. The English name of the lake is thought to be a mis-translation of the proper local name: Grizzly Bear Lake. (Curiously, a mountain on the southwest shore of the lake is correctly named Grizzly Bear Mountain.) Spring runoff into and out of the lake creates attractive fishing spots, especially where the Johnny Hoe River flows into the McTavish Arm. Where the Great Bear River meets the lake, the speed of the rapids means that the surface never fully freezes, allowing for year-round fishing. Historically, the Tłı̨chǫ (Dogrib) and T’atsaot’ine (Yellowknives) indigenous groups fished here and, as often happens when two groups attempt to share the same territory, they occasionally came into conflict. This part of the lake, known as Délįne (meaning “where the water flows”), is the site where the first European outposts were constructed. Fur traders for the North-West Fur Company arrived in the region in the late 18th century. Alexander Mackenzie established an outpost at Délįne in 1799, and in 1825 construction began on the headquarters for Sir John Franklin’s second Arctic expedition, the eponymous Fort Franklin. It was around this time that Franklin, out of a sense of gratitude, named the lake’s five arms in honor of the men who supported him on his journey: Dease, Smith, McTavish, Keith, and McVicar.

The lake and its surrounding territory is also home to an indigenous group, the Dene, whose ancestors have occupied the region for more than 2,000 years. The earliest inhabitants were nomadic, following migrating caribou and muskoxen around the tundra, although archeological evidence suggests that temporary settlements cropped up along the shores of the lake at various locations. It was not until the early 20th century that a permanent indigenous community arose at Délįne, composed mainly of Sahtuto’ine (the “Bear Lake People”). The current population is around 600. Sahtuto’ine culture is intimately connected to the lake, its watershed and the animals that inhabit it. One legend tells of a fisherman who, after diving deep into the lake to retrieve fishing tackle, came across a giant beating heart surrounded by a protective circle of fish. The story reflects the Sahtuto’ine belief that the lake is a living entity, one that gives life to the lakes, oceans, and rivers across the entire world.

Outsiders had come and gone since the time of the first European explorers, but for them the lake provided a base camp or opportunity to fortify themselves before moving on. There was no commerce as such other than fur trading. But then, in the 1930s, circumstances changed drastically. While much of the world knows about the Manhattan Project and the United States’ development–and eventual deployment–of nuclear fission bombs during World War II, few people are aware of Great Bear Lake’s connection to these historic events.

In the early part of the 20th century, the radioactive element radium–made famous by the Nobel-prize-winning experiments of Marie Curie–was used to treat a variety of medical conditions, including cancer, and it was also painted on the hands of timekeeping devices to make them glow in the dark. By the early 1920s, due in part to the difficulty in extracting and refining it, radium was the most expensive substance in the world by weight, selling for over $100,000 per gram ($1.5 million in today’s dollars). The primary source for radium at the time was the Belgian Congo, which held a virtual monopoly on it.

Nineteenth-century explorers to the Northwest Territories left written accounts of witnessing exposed mineral deposits around the region, including on the shores of Great Bear Lake. Based on these accounts, Eldorado Gold Mining Ltd., headed by Gilbert LaBine, began exploratory drilling around the eastern shore of the lake in the hope of finding deposits of copper or cobalt. Neither of these was found in any significant quantity, but what LaBine did discover was a large deposit of pitchblende, a form of uraninite known to contain radioactive isotopes of uranium, polonium, and, of greatest financial value at the time, radium.

Within a few years LaBine had built a large mining operation at Echo Bay and a small community sprang up around it, dubbed Port Radium. By the mid-1930s the area hosted around 200 full-time residents, most providing support for the mining operations and transportation of raw pitchblende to LaBine’s refinery in Port Hope, Ontario. The Canadian government established a post office and radio station at nearby Cameron Bay, as well as a Royal Canadian Mounted Police post. By 1938 the Eldorado mine was producing 2.8 grams of radium per month, refined out of a total pitchblende mass of 18 tons.Then, less than two years later, the mine was quickly abandoned after scientific advances obviated the medical need for radium causing its price to plummet, rendering mining operations too costly to sustain.

This was not, however, the end of the story for mining at Great Bear Lake. During the radium days, uranium was considered a waste byproduct and some 1.7 million tons of “useless” uranium ore was dumped into the lake. But when scientists discovered in 1939 that enriched uranium could be used to make a nuclear weapon, suddenly a wartime race was on to locate sources of it. When the United States failed to secure an agreement with a mining company in Congo, that left Canada as America’s main supplier of uranium ore. At first, LaBine was able to supply uranium ore from his existing stockpiles, but eventually the Manhattan Project’s increased demand led the Eldorado mine to reopen–with the support of the Canadian government. In parallel with the renewed mining efforts, the uranium “waste” that had been cast into the lake was reclaimed through dredging. By the time the two bombs destined to be dropped on the Japanese cities of Hiroshima and Nagasaki were assembled, Great Bear Lake’s pitchblende mining operations had unearthed over 4,000 tons of raw uranium ore, a significant portion of which, once refined and enriched, ended up in the deadly radioactive cores at the heart of those weapons. Although the Canadian government has not publicly acknowledged the country’s role in providing material support for the development of U.S. atomic bombs, in 1998 the Dene people sent a delegation to Japan and offered a formal apology for the role their people played, mainly as mine workers, in the extraction and transportation of the deadly nuclear fuel.

Despite its troubled nuclear history, the lake remains one of the most untouched and pristine bodies of water of its size in the world. In the early 1900s a Sahtuto’ine elder named Eht’se Ayah prophesied that some day, when the rest of the world had depleted its supplies of clean water and food, people would be drawn en masse to Great Bear Lake for refuge and sustenance. He believed at that time the lake would be so crowded with foreign boats that people would be able to cross the lake by simply walking from boat to boat without ever touching the water. The prospect of this prophecy coming to pass, as well as a desire to make sure the lake remains an untouched cultural and environmental resource for generations to come, led to calls for the lake to become an officially protected site. In 2016 Great Bear Lake and its surrounding watershed were named a Unesco Biosphere Reserve. The Tsá Tué Biosphere Reserve, as it is known, is the largest reserve of its kind in North America and is also the first to be led entirely by an indigenous community.


Johnson, Lionel. “The Great Bear Lake: Its Place in History.” Arctic, Vol. 28, No. 4 (Dec., 1975),
pp. 231-244. Accessed April 4, 2023.

Kean, Sam (host). “Crowdfunding Radium.” Distillations, Episode 267, April 12, 2021. Accessed April 11, 2023.

Kujawinski, Peter. “Guardians of a Vast Lake, and a Refuge for Humanity.” The New York Times: Feb. 7, 2017. Accessed April 2, 2023.

Macdonald, Colin, PhD. “Great Bear Lake: State of Knowledge of the Terrestrial Environment.” The Sahtu Renewable Resources Board, March 2004. Accessed April 7, 2023.

Piper, Liza. “Great Bear Lake.” The Canadian Encyclopedia, 2021. Accessed April 5, 2023.

Salverson, Julie. “They Never Told Us These Things.” Maisonneuve, Aug. 12, 2011. Accessed
April 3, 2023.

“Tsá Tué Biosphere Reserve, Canada.” Accessed April 13, 2023.