High contamination levels were found along a North Dakota creek more than a month after a massive wastewater spill was found in the state’s oil patch, but levels have dropped considerably in larger rivers downstream, according to documents released by the state Tuesday.
Results of a preliminary investigation into the pipeline leak, which spilled 3 million gallons of saltwater brine, were obtained by The Associated Press. They show that heavily contaminated surface water was found in recent days on residential property more than a mile away from the spill site north of Williston.
The wastewater is a byproduct of intensive oil drilling in the Bakken region of North Dakota and Montana. It primarily contaminated Blacktail Creek, but also flowed into the Little Muddy River and the Missouri River.
The levels of chloride, or salt, in water samples taken from an oxbow along Blacktail Creek were detected at more than 25 times the state’s water quality standard in the past few days. But the area of highest groundwater contamination – where saltwater has seeped into the surrounding water table – is more limited. It runs along a corridor downstream of the spill site, which is at least several hundred feet wide and about 2,000 feet long.
The findings from a consultant for the pipeline’s owner, Texas-based Summit Midstream Partners LLC, were released to the AP by state health officials under a public records request.