An investigation is under way into what caused a Marathon Oil-operated pipeline to leak produced water into a small creek and stock pond that lie on pastureland in North Dakota earlier this week.
Initial figures from the state's Department of Environmental Quality indicate about 500 barrels of produced water, a byproduct from the hydraulic fracturing process, leaked from the pipeline, which is part of a gathering system operated by Marathon.
The spill occurred in Dunn County about 1.5 miles north-east of the town of Manning on Tuesday and was reported the same day, according to the regulator.
The creek that was affected discharges into the Knife River, which is about one mile downstream of the stock pond. According to the department, no impacts have been detected in the river.
A cause has not yet been identified, but staff from the department were inspecting the site and monitoring the investigation.
Marathon Oil did not immediately respond to a request for comment.
