The Dakota Access Pipeline leaked roughly 84 gallons of oil from a surge pump in April.
On April 4, the pipeline reportedly spilled 84 gallons of oil in rural South Dakota after a surge pump suffered mechanical failure, NBC News reports. The spill was promptly cleaned up, but not publicized by the state.
"We do not generally public notice a spill unless there is an imminent threat to public health, a drinking-water system, or surface-water body," Brian Walsh of the South Dakota Department of Environment and Natural Resources told Vice. "We treated this 84-gallon spill just as we would treat any other 84-gallon spill that occurs in our state."
Energy companies are not legally obligated to disclose pipelines leaks to the federal government unless they amount to 210 gallons or more.
The spill was contained and reportedly had no lasting environmental impact, but rekindled concern among the Native American tribes that protested the pipeline, citing that it would endanger their reservation's source of drinking water.
"I would characterize it as a small operational spill that was cleaned up right away," Walsh told The Associated Press.
The Dakota Access Pipeline is scheduled to become operational on June 1. The controversial project, headed by Energy Transfer Partners, would stretch from North Dakota to Illinois and has been heavily protested by environmental activists and Native American tribes.
The Standing Rock Sioux Tribe, which has an ongoing lawsuit against the project, had repeatedly requested that the pipeline be rerouted to avoid the Lake Oahe reservoir along the Missouri River, the tribe's primary source of drinking water.
In December 2016, the U.S. Army Corps of Engineers delayed construction of the pipeline to explore potential alternative routes. They abandoned the delay upon the arrival of the Trump administration.
On Jan. 24, President Donald Trump signed an executive order expediting construction of both the Dakota Access and the Keystone XL pipelines. The directive was among his first actions as president, CNBC reports.
Standing Rock Indian Reservation Chairman Dave Archambault released a statement blasting the April spill, asserting that the incident vindicates his tribe's concern.
"The Dakota Access pipeline has not yet started shipping the proposed half million barrels of oil per day and we are already seeing confirmed reports of oil spills from the pipeline," Archambault said, according to NBC News. "This is what we have said all along: oil pipelines leak and spill."
Program director with Pipeline Safety Trust Rebecca Craven described the incident as relatively common, but troubling.
"These kinds of spills do occur..." Craven said. "...It's very hard to extrapolate from this to guess how many problems there will be with Dakota Access in the future. But it's an indication that it's not perfect and it's really hard to build a pipeline that's perfect."