Hundreds of people in British Columbia can’t use their water after more than a billion gallons of mining waste spilled into rivers and creeks in the province’s Cariboo region.

A breach in a tailings pond from the open-pit Mount Polley copper and gold mine sent five million cubic meters (1.3 billion gallons) of slurry gushing into Hazeltine Creek in B.C. That’s the equivalent of 2,000 Olympic swimming pools of waste, the CBC reports. Tailings ponds from mineral mines store a mix of water, chemicals and ground-up minerals left over from mining operations.

The flow of the mining waste, which can contain things like arsenic, mercury, and sulfur, uprooted trees on its way to the creek and forced a water ban for about 300 people who live in the region. That number could grow, as authorities determine just how far the waste has traveled. The cause of the breach is still unknown.

So far, water-use bans have been issued for the town of Likely and for people living near Polley Lake, Quesnel Lake, Hazeltine Creek (which flows into Quesnel Lake), and Cariboo Creek, as well as the Quesnel and Cariboo River systems. Authorities so far haven’t issued water bans for the Fraser River – […]