Spotted Lake: Canada's soda lake with colorful brine pools that are smelly and slimy 'like the white of an egg'

Spotted Lake — also known as Khiluk Lake in the local Indigenous Nsyilxcən language — is a soda lake named after strange circles that appear on its surface in the summer.

The lake is incredibly rich in minerals, including sodium sulfates, calcium, magnesium sulfate — which is also known as Epsom salt — and trace amounts of silver and titanium. As temperatures rise every spring and summer, most of the water in the lake evaporates and minerals that were dissolved precipitate, leaving a pitted, white crust that looks like a giant doily.

The mineral crust exists year-round and can be seen beneath the water outside of summer, but the best time to see it is in the hotter months. Spotted Lake has no outlet, meaning evaporation is the only process that removes water from the lake. Precipitation and runoff from the surrounding hills increase the water level periodically, which also brings more minerals that crystallize into the crust.

Spotted Lake is a soda lake, meaning it is extremely salty and alkaline. Soda lakes typically form in closed basins, where minerals leach from surrounding rocks and become highly concentrated.

The lake is 2,300 feet (700 meters) long and 820 feet (250 m) wide. The darker spots in the mineral crust are shallow brine pools, beneath which there are more solidified minerals. These pools can appear blue, green or yellow, depending on the light, the makeup of the crust underneath, and the presence of algae. They can also change size and shape as the crust crystallizes and dissolves.

Geologist Olaf Pitt Jenkins described the texture and smell of the brine at Spotted Lake in a 1918 paper, writing: "The brine itself in the pools was so strong that it was very heavy and very slimy like the white of an egg, and had an offensive odor."

Jenkins visited Spotted Lake because, starting in 1916, the lake's minerals were extracted to make ammunition during World War I. However, Spotted Lake's history and cultural significance goes back much further than that.

For centuries, the Syilx People of the Okanagan Nation have considered Spotted Lake a sacred place of healing. According to their belief, each circle in the lake has unique medicinal properties.

After World War I, the land where the lake sits was acquired and privately owned for about 40 years. But in 2001, the federal government bought back the land for the benefit of the Okanagan Nation. The Syilx People still protect Spotted Lake today, and access to the water is restricted for the general public. A viewing area guarantees good views of the lake, however.

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