BOWMAN COUNTY, N.D. - A pipeline leaked about 2,000 barrels, or 84,000 gallons, of source water to flow into Skull Creek in Bowman County on Thursday afternoon, according to an incident report from the North Dakota Department of Health said on Friday, Dec. 2.
Source water is used for enhanced oil recovery and is higher in chloride than fresh water, but does not carry the same environmental implications as produced water.
Bill Suess, spill investigation program manager with the Health Department's water quality division, said approximately 1,900 barrels, or 79,800 gallons, of the source water released into the creek.
The leak occurred about 20 feet away from the creek, causing the source water to flow northwest for approximately half a mile, according to the report. In a press release the NDDoH said the spill was a result of "equipment failure," but did not expand further on that.
Source water, Suess said, is groundwater that is "a little higher in chloride in total dissolved solids than drinking water standards, but it is not produced water."
According to Suess, the drinking water standard for chloride is 250 ppm (parts per million). The chloride readings registered at the source of the release were between 400-600 ppm, with readings dropping below 300 ppm approximately a quarter mile and a half mile downstream.
He added that produced water, which is water that is brought to the surface along with oil or gas, has a much higher chloride reading, sometimes up to 180,000 ppm.
Suess said the spill should not have an effect on drinking water for the residents of Bowman County, but said ranchers should take a bit of caution if their cattle drink from Skull Creek as the chloride readings are slightly higher than normal.
"It doesn't look like the creek has been impacted to where it would be detrimental to cattle, but it never hurts to take precautions," he said. "I think within a day or two everything that went through would be so diluted that it wouldn't be an issue. But, it wouldn't hurt to keep cattle away from the creek for a day or two."
An official with Denbury Onshore, the company responsible for the leak, said the pipeline will be repaired after it is excavated to determine the cause of the leak.
"We investigate really thorough," Mark VanGrinsven said. "We want to know too. Why did this happen? Was there anything we could have done?"
VanGrinsven said that while they do not know what caused this leak, typically these types of spills occur because from corrosion due to the age of the pipeline.
This particular one has been in the ground for decades. The company does nearly daily checks of the pipeline to ensure that everything is safe, and that, if there is an incident, it can be remedied as soon as possible, VanGrinsven said.
The line will remain closed until repairs are made.