A federal agency won’t release a study about the potential effects of a Dakota Access Pipeline oil spill because it claims information in the report could put lives at risk.

The U.S. Army Corps of Engineers made the claim while rejecting a Freedom of Information Act request from MuckRock, a journalism website that collects and publishes government documents.

MuckRock’s co-founder Michael Morisy had requested in March a copy of an Army Corps environmental assessment that looked at the possible impact of a pipeline leak on Lake Oahe in North Dakota.

“The referenced document contains information related to sensitive infrastructure that if misused could endanger people’s lives and property,” said Army Corps lawyer Damon Roberts in a denial letter that MuckRock published Tuesday.

Rather than editing out sensitive details, Roberts withheld all materials related to the request.

“I understand exempting some details, but knowing the impact of a natural disaster should be public,” Morisy told HuffPost. “I was very disappointed.”

MuckRock plans to appeal the Army Corps’ decision, Morisy said.

The assessment’s existence was mentioned in an internal Army Corps memo about the controversial 1,172-mile pipeline, which will carry North Dakota crude oil through South Dakota and Iowa to Illinois.

The memo mentioned that several documents were withheld from the public and from representatives of a Native American tribe that has objected to the project “because of security concerns and sensitivities.”

Lake Oahe is near the Standing Rock Sioux Reservation in North Dakota, which saw large-scale demonstrations from last summer until February as the Standing Rock Sioux and other nearby tribes argued that the project could contaminate their drinking water. They’ve also argued that Army Corps officials didn’t conduct a proper environmental study of the project.

Officials of the pipeline’s lead developer, Energy Transfer Partners, have said the risk to the water supply is minimal because the pipe is buried deep beneath the lake and safety features would halt an oil spill after detecting a leak.

With approval from President Donald Trump, the developer has completed drilling under Lake Oahe and announced that the pipeline could be in service as soon as May 14.

Army Corps officials did not immediately respond to HuffPost’s request for comment.