BISMARCK, N.D.  — The Dakota Access pipeline leaked 84 gallons of oil in South Dakota early last month, which an American Indian tribe says bolsters its argument that the pipeline jeopardizes its water supply and deserves further environmental review.

The April 4 spill was relatively small and was quickly cleaned up, and it didn’t threaten any waterways. The state’s Department of Environment and Natural Resources posted a report in its website’s searchable database, but it didn’t take any other steps to announce it to the public, despite an ongoing lawsuit by four Sioux tribes seeking to shut down the pipeline.

Brian Walsh, an environmental scientist with the agency, said Wednesday that the state doesn’t issue news releases on spills unless there is a threat to public health, a fishery or a drinking water system. He said there was no such threat with the Dakota Access leak, which happened nearly 100 miles east of the Missouri River’s Lake Oahe reservoir, which is the tribes’ water supply.

“We realize Dakota Access gets a lot of attention. We also try to treat all of our spills in a consistent manner,” Walsh said. “We treated this as we would treat any other 84-gallon oil spill.”

The leak occurred at a rural pump station in the northeast of the state as crews worked to get the four-state pipeline fully operational, Walsh said.

The oil was contained on site by a plastic liner and containment walls and quickly cleaned up. Some oil-contaminated gravel will be disposed of at an area landfill, he said.