Residents of the eastern Montana city of Glendive have been advised to use bottled water for drinking and cooking after an oil pipeline burst at the weekend, sending crude oil into the Yellowstone River, CBS News reported.

Latest estimates suggest that about 960 barrels (or 40,000 gallons) of Bakken crude oil were discharged into the river as a result of the leak in the Poplar pipeline, which is operated by Bridger Pipeline LLC and runs from the Canadian border to Baker, Mont. Earlier estimates had calculated a worst-case discharge of up to 1200 barrels (50,000 gallons) of oil.

Traces from the oil spill were detected in public water supplies, with tests on Monday picking up elevated levels of volatile organic compounds (VOCs), predominantly benzene. Glendive City Council member Gerald Reichert was among the residents who noticed a smell like diesel fuel in the tap water.

Local people were advised to not drink or cook with the water, and instead use drinking water that had been shipped to the city and was available to pick up from the Eastern Plains Event Center.

Meanwhile, at the Glendive Water Treatment Plant workers have been working to remove the contamination and bring the municipal water system back online.

The facility has increased the dose of activated carbon, which removes contaminants. If that proves inadequate, air stripping equipment will be added to pretreat the water as it comes into the plant.

Residents will be able to resume using their tap water once Montana's Department of Environmental Quality certifies the water safe at the plant and the system is flushed.