Montana Gov. Steve Bullock on Monday declared a state of emergency in two counties along the Yellowstone River that were hit by a spill of up to 50,000 gallons of crude oil Saturday morning. State officials said there was no threat to public safety or health.

Representatives from the U.S. Environmental Protection Agency (EPA) and from the Montana Department of Environmental Quality (DEQ) were assessing the situation at the source of the spill, about nine miles upriver from Glendive, MT, in Dawson and Richland counties, in the far east-central portion of the state.

A spokesperson for Bullock told local news media that the leak was spotted relatively quickly and the 12-inch diameter pipeline crossing the river and operated by Dallas-based Bridger Pipeline Co. had been shut down.

The pipeline was shut down within an hour of the spill being detected by a pressure drop, according to Bridger Vice President Tad True. A spokesperson did not immediately respond to an inquiry from NGI‘s Shale Daily.

In a report in local news media, True said Bridger’s primary concern was to minimize the environmental impact of the release and keep responders safe as the incident is cleaned up. Bullock’s spokesperson told local media some oil did get into the water, but it was in a frozen-over area, which should help reduce harm.

Bullock said a sheen was detected on Sunday from the pipeline crossing as well as further downstream. Bridger reported that up to 300 bbl of crude may have been released. “Montana has taken an active role in the oversight of this hazardous materials response” in coordination with the EPA, Montana DEQ and at least three other state and federal agencies, the executive order said.

DEQ reported on Monday that municipal water systems downstream of Glendive were notified by the agency, including Sidney, MT, and across state lines in Williston, ND. “The municipal water systems are not experiencing any issues, but they are having their water tested,” DEQ said in a bulletin posted on its website.

Using the standard calculation of 42 gallons of crude in every barrel of oil, if the spill was as large as the estimated 50,000 gallons that would equate to nearly 1,200 bbl.

This is the first significant spill in Montana since an ExxonMobil Corp. pipeline broke in south-central Montana near Laurel in July 2011, releasing 63,000 gallons of crude along an 85-mile stretch of the Yellowstone River. ExxonMobil is facing several millions of dollars in state and federal fines related to that spill.