Residents in a Montana community affected by the Yellowstone River oil spill are urged to find alternative sources of drinking water, a county government said.

Bridger Pipeline confirmed a release from its Poplar pipeline system during the weekend. Responders said as much as 1,200 barrels of crude oil spilled because of undetermined causes.

Emergency managers in Dawson County, an area near the spill, said water samples showed high levels of benzene and other organic compounds present in the regional water supply. Drinking water is available to the community while workers install additional treatment capacity to the area water treatment plant.

County officials estimate about 960 barrels of oil made its way into the Yellowstone River.

"Residents will be able to resume using their water once the water quality is determined safe," emergency managers said in a late Tuesday statement.

Montana Gov. Steve Bullock, who declared a state of emergency for the affected counties, said Monday he ordered state agencies to deliver bottled water to area residents.

"Local, state, and federal officials are working together to quickly assess this situation, and ensure that those responsible are held accountable, the oil is cleaned up and all damages are addressed," he said in a statement.

Bridger declared force majeure over the Poplar pipeline, meaning it's freed from contractual obligations because of circumstances beyond its control. The pipeline will be shut down indefinitely due to "an apparent" release, the company said.

About 1,200 barrels of oil spilled from the Silvertip pipeline in Montana in 2011.