A pipeline carrying crude oil through North Dakota broke open and spilled into a creek about 150 miles from the Dakota Access Pipeline protests that have been warning about such a spill for nearly a year.

The Belle Fourche Pipeline, which is owned by a different company than the one building the Dakota Access Pipeline, spilled more than 176,000 gallons of crude oil into Ash Coulee Creek around Dec. 5, according to CNBC.

Electronic monitoring equipment designed to detect leaks failed to catch the incident, the pipeline owner said. Wendy Owen, a spokeswoman for True Cos., which owns the pipe, told the Associated Press it was not yet clear why the equipment failed.

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A landowner discovered the spill near Belfield, N.D., according to the report, and the leak was contained within a few hours, but not before it had traveled about six miles along the creek.

The Standing Rock Sioux tribe has argued in its ongoing protests that one reason the Dakota Access Pipeline should not be built near its lands it that a leak could contaminate the tribe’s water supply at Lake Oahe, along with the Missouri River.

The pipeline’s owners have said there would be safeguards against a leak. The DAPL will be nearly 1,200 miles long and will transport nearly half a million barrels of crude oil per day if it is opened.

Last week, the U.S. Army Corps of Engineers said it would explore rerouting the DAPL.

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About 37,000 gallons of oil have been recovered from the Belle Fourche spill, state environmental scientist Bill Suess told the Associated Press.

"It's going to take some time," Suess said. "Obviously there will be some component of the cleanup that will go toward spring."

True Cos. also had a pipeline spill into the Yellowstone River in January, 2015, according to the report.