A cultural nonprofit sued the Trump administration on Monday in an effort to block its ongoing repainting of the reflecting pool on the National Mall to make it “American Flag Blue.”

In papers filed in federal court in Washington, attorneys for Cultural Landscape Foundation argue that the resurfacing of the historic pool is “unlawful,” and it should be restored to its original color until the administration follows Congressionally mandated procedures to do the work.

The lawsuit asks a judge to immediately stop the work, which is being directed and overseen by President Donald Trump, who chose the color himself. The president has said he expects the work to be finished within the next two weeks.

The suit says that color is the main issue with the work being done on the 104-year-old pool.

“The dark grey, achromatic basin was not incidental to the design. It was the design,” attorney Alexander Kristofcak wrote.

“The 1999 National Park Service Cultural Landscape Report for the Lincoln Memorial Grounds specifically identifies the dark-tiled basin as a character-defining feature of the historic landscape, noting that ‘the dark color of the tile created the illusion of greater depth and a more profound reflection,’” the suit says.

“The new coloration will cause the pool to resemble a large swimming pool rather than the reflective civic landscape it was designed to be, distorting the experience of the site for the millions of visitors who come to it each year.”

The White House referred a request for comment on the suit to the Interior Department. A spokesperson for the agency said in a statement that the new color “will enhance the visitor experience by making the pool reflect the grand Lincoln Memorial and Washington Monument.”

The spokesperson added the National Park Service “is also investing in a state-of-the-art ozone nanobubbler filtration system and will now have a dedicated crew who will maintain the grounds from wildlife.” The statement said the work will “ensure this magical spot can be enjoyed for not only our 250th” national birthday celebration “but for many generations to come.”

Trump touted the new color while visiting the site last week.

“It’s going to be a beautiful color,” he said. “The color was never good, because basically it had a gray stone underneath, whether it was the concrete or the granite, it was a gray stone. And now we actually picked the color, it was called American Flag Blue, and so you can’t do better than that.”

The suit alleges the administration has ignored proper procedures, including following Section 106 of the National Historic Preservation Act, which requires agencies to engage in a process of consultation before making changes to historic properties by consulting with experts and nonprofit organizations with relevant expertise that provide input on proposed changes.

“No consulting parties have been notified, engaged, or given an opportunity to participate,” it said.

The suit noted that the current administration has a history of plowing ahead with such changes without following lawful procedure. It’s currently facing similar lawsuits related to construction projects involving the White House ballroom and the Kennedy Center.

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“This latest desecration of the reflecting pool is part of a pattern—epitomized most notably by the rush to destroy the East Wing of the White (House) —in which this Administration willfully disregards legal limits established by Congress,” the suit said.

The group argued that time is of the essence.

“Every day that the resurfacing continues, the historic character of the Reflecting Pool is being further and fundamentally altered,” its suit said. “The Court should act now, halt further resurfacing, and require Defendants to comply with the law they have bypassed.”

Trump announced the project on April 23. “In another couple of weeks, we’re going to have the most beautiful reflective pool between the Washington Monument and the Lincoln Memorial that you’ve ever seen,” Trump said, calling the work necessary because the pool “was filthy, dirty, and it leaked like a sieve for many years.”

An Interior official said the pool leaks 16 million gallons a year, and the coating material being used is leak-proof.

The New York Times, citing federal records, reported Monday that the government is paying $13.1 million for the project through a no-bid contract awarded to Atlantic Industrial Coatings, which had previously performed work at Trump’s property in Sterling, VA.

NBC News has not independently verified the figure. Asked to comment, the spokesperson for the Interior said, “The contract price reflects the effort necessary to expedite the timeline of completing the leak prevention coating project—more people, more materials, more equipment and longer hours ahead of our 250th.”

The department also said the NPS “chose the best company to expedite the repair of the iconic Reflecting Pool ahead of our 250 celebrations.”

Trump told reporters last week the work is being done at a bargain rate, citing a figure much smaller than the one the Times reported.

“So we had estimates to fix it of about $355 million and it was going to take three and a half years, you can see by the size of it. And so we’re going to be able to do it for about $1.8 million, and it’s going to take one week, and we’ll be finished. I guess I’m going to give him a little more time. Let’s give it two weeks, but we’re pretty, a lot of the hard work is done,” he said. “The beautiful work is now,” he added, referring to the paint job.

The color is “like a swimming pool, but industrial strength much stronger. And I think you’re going to see something that’s amazing,” Trump said.

Trump has embarked on a number of major renovations since the beginning of his term, many of which are caught up in legal challenges.

A federal judge has ordered work on his much-discussed ballroom to be halted, but an appeals court has allowed the work to proceed at least temporarily while it considers the government’s appeal. Challenges to the closure and renovation work at the Kennedy Center, as well as the addition of Trump’s name to the center, are also pending.

Concerns over the speed with which the administration has been acting have also led to a preventive suit over Trump’s announced plans to build a 250-foot-high arch near the Potomac River. A federal judge has ordered the National Park Service to provide her with a 14-day notice before any construction occurs on Memorial Circle in furtherance of the planned arch.