The Trump administration violated federal law when it diverted national parks fees to support basic park operations during the federal government shutdown that began last year and dragged on for 35 days into this year, according to a new report issued by the Government Accountability Office.

Despite pleas from park advocates to close the parks during the shutdown, the Interior Department kept these national treasures open without adequate staffing, even as trash piled up, vandals damaged park resources, and restrooms basked in malodorous filth.

The neutral government watchdog affirmed park advocates’ assessment: Interior Secretary David Bernhardt blatantly disregarded laws guiding how federal dollars are to be spent when he diverted up to $253 million to tidy up the parks as the shutdown dragged on.

"While the Department of the Interior should correct its Antideficiency Act violation, it must report the violation to Congress and enumerate actions it has taken to prevent recurring violations in the event of future funding lapses," stated the report. "With this decision, we will consider such violations in the future to be knowing and willful violations of the Act."

At issue is the Federal Lands Recreation Enhancement Act, which limits the National Park Service’s use of entry fee dollars to visitor-related maintenance and improvements to either buildings or natural and cultural resources, with an eye toward education.

Interior promptly rejected what it called an “erroneous opinion" from the Government Accountability Office, known as the GAO.

“It’s obvious that the GAO reached their conclusion prematurely and without regard for all of the facts,” the agency said in a statement provided by spokeswoman Melissa Brown. "The department acted well within its legal authority to clean up restrooms and pick up trash, so the American people could enjoy their national parks.”

Yet under Interior’s own contingency plan for government shutdowns, the Park Service was to “cease providing visitor services, including restrooms, trash collection, facilities and road maintenance (including plowing), campground reservation and check-in/check-out services, backcountry and other permits, and public information." While parks would remain open, staffing would be maintained only at a level needed to protect property and public safety.

But on Jan. 5, two weeks into the shutdown, Bernhardt sent a memo to Deputy Director Daniel Smith directing him to tap park fees to address the sanitation crises building at the parks, as well as for road maintenance, campground operations and providing the public critical safety information.

"These operations shall be maintained until such funds have reached a zero balance," the memo said.

GAO investigators had asked Interior officials to provide their legal rationale and documentation supporting the controversial move, but they never responded.

“We ... will not allow an agency’s lack of cooperation to interfere with Congress’s oversight of executive spending,” the report said. “In this case, we reviewed publicly available documents.”

House Republicans used the report as an opportunity to attack President Barack Obama’s approach to the 2013 shutdown, where his administration shuttered the parks for 13 days. Obama’s NPS Director Jonathan Jarvis, however, felt a degree of vindication by the GAO report.

“They [House Republicans] said it was a political stunt to close the parks. It was not. It was in compliance with the law,” said Jarvis, who now directs the University of California’s Institute for Parks, People, and Biodiversity.