The path of brine spilled from an underground North Dakota oil pipeline extends nearly 2 miles down a steep ravine, but dead vegetation is limited to about 200 yards from the source of the spill, an executive from the company responsible for the leak said Thursday.
Miranda Jones, vice president of environmental safety at Crestwood Midstream Partners, said the cause of the spill appears to involve a separation of the pipe that carries saltwater, a byproduct of oil and natural gas production. Crestwood subsidiary Arrow Pipeline owns the pipeline.
Jones said the path of the brine is 8,240 feet long, and the company has estimated that around 1 million gallons were spilled. Officials have said it damaged trees, brush and grasses in the area.
Claryca Mandan, natural resources administrator for the Mandan, Hidatsa and Arikara Native American tribes' natural resources department, said the area is "one of the worst places it could have happened" because the pipeline sits atop a bluff, and the saltwater ran down the rugged terrain.
Saltwater is a naturally occurring, unwanted byproduct of oil and natural gas production that is between 10 and 30 times saltier than seawater. The state considers it an environmental hazard.
The byproduct, also called brine, may contain petroleum and residue from hydraulic fracturing operations.
The Environmental Protection Agency was assessing the site Thursday to ensure that none of the brine affected the lake a Native reservation uses for drinking water.
In the first public statement in the two days since the spill was detected, the agency said it had no confirmed reports that the saltwater had reached Bear Den Bay. It leads to Lake Sakakawea, which provides water for the Fort Berthold reservation in the heart of western North Dakota's booming oil patch.
The EPA said most of the spill was pooled on the ground, soaked into the soil or held behind beaver dams.
Cleanup at the reservation site is expected to last for weeks, Jones said.
The leak likely started over the Fourth of July weekend. The pipeline was not equipped with a system that sends an alert when there is a leak, she said, and the spill was discovered only when the company was going through production loss reports.
Although the EPA said additional assessment activity was being conducted, company and tribal officials said the spill had been contained and did not affect the lake.
"We have a berm and a dike around it, around that bay area, to keep it from going into the lake," said Three Affiliated Tribes Chairman Tex Hall.
Karolin Rockvoy, a McKenzie County emergency manager, said it was apparent from looking at vegetation that the spill went undetected for some time.
From oil to radioactive waste to saltwater, spills and even rail accidents involving trains carrying oil from North Dakota's Bakken field have become increasingly common since the state's energy industry began expanding rapidly.
North Dakota produced 25.5 million barrels of brine in 2012, the latest figures available.
The Fort Berthold Indian Reservation plays a key role in the state's oil production, the second highest in the nation. The reservation currently produces more than 300,000 of North Dakota's 1 million barrels of oil produced daily, according to the state's Department of Mineral Resources.
The Associated Press