- An oil pipeline that crosses the Yellowstone River burst near Glendive, Montana
- The Yellowstone River is the longest undammed river in the United States
(CNN)A Montana pipeline burst sent as much as 50,400 gallons of oil gushing into the Yellowstone River, prompting the governor to declare a state of emergency.
Residents in nearby cities were told not to drink the tap water, which some said smelled like diesel.
The massive oil spill happened when the 12-inch pipeline, which crosses the Yellowstone River, ruptured Saturday about 5 miles upstream from Glendive, Montana's Department of Environmental Quality said. The Bridger Pipeline company shut down the pipeline.
Glendive City Council member Gerald Reichert was among the residents who noticed a disturbing odor in the drinking water.
"Suddenly at our house there was a definite smell. It was a diesel smell," Reichert told the Grand Forks Herald.
Montana Gov. Steve Bullock announced a state of emergency for Dawson and Richland counties.
And while officials wait for results from water sample testing, they're advising residents to use bottled water for drinking and cooking.
A host of agencies have responded to the oil spill, including the Environmental Protection Agency and the Department of Health and Human Services.
Adding to the problems, the weather: the Yellowstone River is partially frozen, making it difficult to clean up the mess.
This isn't the first major oil spill into the Yellowstone River -- the longest undammed river in the United States.
In 2011, up to 42,000 gallons poured out of a ruptured Exxon Mobil pipeline.