Glendive's water supply was shut down briefly this weekend due to contamination from the January 17 oil spill into the Yellowstone River.
Equipment installed near Glendive's water intake system detected elevated levels of volatile organic compounds early Saturday morning.
That prompted city officials to issue an advisory to conserve water. That forced residents to rely on bottle water through the weekend.
That advisory has since been lifted.
Bridger pipeline spokesman Bill Salvin says the plant was shut down only as a precautionary measure.
"The equipment that we installed worked exactly as it was supposed to work. That's the most important thing; at no point this weekend was the city water contaminated. It was clean and safe to drink all weekend."
Ice is starting to melt on eastern Montana's Yellowstone River and that means more oil is releasing into the water.
A January pipeline failure spilled 30,000 gallons of crude in the river.
Thousands of residents had to rely on bottled water for days following the accident.
Workers have recovered only about 10 percent of the spilled oil.