WASHINGTON—It is the start of summer and President Trump has a pool problem.

A government contractor resurfaced the Lincoln Memorial Reflecting Pool on the National Mall with what the president has referred to as an “American Flag” blue coating .

Within days of the pool’s reopening, algae blooms coated the floor with a thick residue reminiscent of the neon green slime left behind by the Ghostbusters. Some of that algae has floated to the top and is streaking the surface.

That has attracted a parade of onlookers eager to see and, in some cases, diagnose the situation. The pool’s evolving shades of green have caused a stir on social media with many mocking the results of Trump’s pet project.

Ducks swam along the algae-coated waters on Tuesday. REUTERS/Eric Lee

Water containing algae is pumped into a drain from the Lincoln Memorial Reflecting Pool, after recent renovations following a directive from U.S. President Donald Trump to paint it blue ahead of the 250th anniversary of U.S. Independence, in Washington, D.C., U.S., June 16, 2026. REUTERS/Eric Lee

The Interior Department contracted to spend $14.7 million on the renovation and repair work it finished last week. On Tuesday, photos appeared online of workers dumping gallon jugs of hydrogen peroxide into the pool.

Pool maintenance buffs have taken to Reddit to offer tips , with one suggesting instead that the government “slam it with chlorine,” a more aggressive chemical.

Workers on Wednesday were spotted in fishing waders standing knee-deep in the water vacuuming the bottom surface. A humming from generators running along the water’s edge muted the usual buzz of tourists. Late that night, the Interior Department announced the pool was “crystal clear” and said workers were sucking up the dead algae.

While those efforts appeared to have yielded some improvement on Thursday, much of the pool was still green and algae appeared to already be growing back in the places that had been cleared. The cleaning efforts also appeared to have dislodged chunks of the lining, leaving new white patches visible on the bottom.

David Bidelspach, whose Colorado-based company does work restoring natural streams and rivers, stopped by the scene while on a trip with his family this week. The unwanted aquatic occupant grows at an exponential rate and blooms can double in size in a day, Bidelspach said.

A tear in the pool’s recently applied sealant could be seen through the algae-laden water on Thursday. REUTERS/Annabelle Gordon

He scraped the bottom of the pool with his fingernails and provided a few treatment tips of his own. Hydrogen peroxide will get rid of algae blooms if enough is used, he said, but it has to be mixed into the water appropriately. That is hard to do in a structure that is about 2,000-feet long.

The right dose of hydrogen peroxide would be “very, very high and they would have to stir it throughout the entire reflecting pool,” Bidelspach said.

Some visitors said they were grateful the pool was getting a face-lift, but others were skeptical of the improvement efforts. “I think it’s a waste of my taxpayer dollars,” said Wes Ledyard, of Shelby, Mich. “I’ve been here before and I didn’t see anything wrong with it the first time I came.”

She said Trump’s changes to the reflecting pool seem like “a vanity project.”

Interior Department spokeswoman Katie Martin said the hydrogen peroxide the National Park Service is using “is a milder treatment than chlorine and is used in spas and specialty pools like natural swimming pools.”

Martin said the department is also “deploying high-tech nanobubble ozone technology” to kill algae and other contaminants that “have long plagued the Reflecting Pool.”

Algae thrives in warm, shallow water. That has long made the reflecting pool, which is only 3-feet deep, a perfect breeding ground. Trump promised to clean the “filthy” pool and fix the leaks as part of his efforts to beautify the nation’s capital in his second term.

Construction workers paint the Lincoln Memorial Reflecting Pool blue at the directive of U.S. President Donald Trump, ahead of America 250, in the National Mall in Washington, D.C., U.S., June 3, 2026. REUTERS/Nathan Howard

Part of the renovation included changing the color of the basin from gray to navy blue , which may have had the unintended effect of making the water even warmer.

A White House spokeswoman said the pool was leaking 16 million gallons of water a year before Trump sealed it with a new lining. During a visit to the site last month, Trump said that the pool had previously been full of trash. “This place was a disgusting place,” he said.

The Interior Department completed the renovation at lightning speed by government standards.

A local nonprofit sued the administration, claiming it sidestepped required reviews before undertaking the project in mid-April. The government finished the job before a judge had decided whether to step in.

The government awarded the resurfacing contract to Virginia-based Atlantic Industrial Coatings, without going through a full bidding process.

The Lincoln Memorial Reflecting Pool on Thursday. REUTERS/Annabelle Gordon

Reached by phone, the company’s co-owner Eddie Wood said the government did entertain presentations from two companies that make the material used to line the bottom. He declined to comment on what has grown there since he left.

“I was hired to put a liner in the pool,” he said. “That’s all I did.”