Trump Promised Clear Water. The Reflecting Pool Went Green.

Fresh off a multimillion-dollar renovation ordered by President Donald Trump, the Lincoln Memorial Reflecting Pool is now a sea of green.

The president had wanted a pool filled with clear water and a bottom painted "American Flag Blue," the color of a commercial-grade swimming pool liner he had added to the granite pool to address leaks and spruce up the monument ahead of huge Independence Day celebrations this summer on the National Mall to commemorate the nation’s 250th birthday.

Instead, dark green clumps of algae sat Tuesday morning on a lighter green layer of algae that’s blanketed the water.

Algae started forming in the pool last week, within days of the renovation's completion. An Interior Department spokesperson Friday said the agency would remove the algae and use “nanobubblers” to keep it clean. But the algae has quickly spread.

Brooks Barrett, who studies marine plant life at the Smithsonian Institution, said there’s “no quick fix” to the algae bloom in the pool.

“The reflecting pool is perfect for algae. If you were trying to biofarm algae, this would be the way to go. It’s warm, it’s stagnant, it’s perfect,” he said.

On Tuesday morning, white foam billowed out from hoses connected to machinery carrying the label of Green Water Solutions. The Ohio-based contractor was paid $1.7 million by the National Park Service to install an ozone nanobubbling system, which Interior has said would keep the pool algae-free. A worker from contractor Pearl Purity Water Solutions, which has treated water in the pool since 2021, was also seen vacuuming algae off the bottom of the pool.

Green Water Solutions did not respond to a request for comment. Pearl Purity Water Solutions could not be reached.

Around the pool, visitors from outside Washington mentioned that they had seen reports of algae forming from the past week but didn’t expect it to be so widespread.

“Well, it’s really green,” said a tourist from California.

Interior on Tuesday said it is working to kill the algae using the nanobubbling system and hydrogen peroxide.

"The National Park Service is actually maintaining the beautifully completed Reflecting Pool," the department said in a statement. "To keep the water in the Reflecting Pool not only crystal clear but also clean, we are deploying high-tech nanobubble ozone technology. ... Additionally, hydrogen peroxide, which is a milder treatment than chlorine and is used in spas and specialty pools like natural swimming pools, is also treating the pool."

The hydrogen peroxide will have no harmful effect on marine animals or the environment, the department said.

Explosions of algae are a regular problem the agency has confronted at the shallow pool. But the growth has dealt a blow to the White House's efforts to clean up the famous memorial — and at a bargain rate — before July 4.

Trump announced the plan to renovate the pool with a commercial swimming pool liner in April, promising to cheaply fix what previous presidents had burned money on.

“The Biden administration and the Obama administration spent hundreds of millions of dollars trying to get it to work, and they failed,” Trump said at the time, referring to a $34 million renovation of the monument in 2012 completed during the Obama administration. That work sought to address algae issues, stagnant water and leaks, although once it was done both the leaks and algae resurfaced.

The National Park Service had received bids to try again with a total renovation of the granite and grouting. But that could have cost hundreds of millions, Trump said earlier this spring.

His solution was to use swimming pool contractors to coat the granite with a spray-on liner, saying the total cost would be between $1.5 million and $2 million. That cost later ballooned to $14.2 million, according to federal records.

Questioned on whether the NPS’ more extensive renovation plan would be a superior project to the pool liner, Trump said in April he had disagreed.

“No, this is much better … for much less money,” he recalled saying. “It will look far more beautiful, more beautiful than it did in 1922 when they built it.”

Kym Hall, the former regional director for NPS’ capitol region, said Trump’s fix ignored the larger, more expensive, problems that the pool faced. She noted that the filtration system and piping need renovations.

“I’m not sure how this administration thought they were going to somehow overcome a long-standing challenge of keeping [the pool] clear (not to mention wildlife contributing waste to the water) by painting it,” she said.

Last week Interior said the algae came from water in the pipes that had been left to stagnate while the pool was being renovated. When the pool was refilled after the pool liner was applied, it carried those contaminants into the pool.

Hall said that explanation was possible. The pipes and filtration system hold about 500,000 gallons of water of the roughly 4-million-gallon system, which is fed from the water in the Tidal Basin. NPS treats the water with ozone, which helps kill bacteria and depress algae growth.

“Trying to keep the algae at bay is a huge battle. So, they clean it each year and keep trying to keep it clean,” she said. “If this problem could have been easily solved or cheaply solved, somebody would have freaking done it."

NPS is juggling a backlog of more than $24 billion in maintenance needs across the country, with nearly $3 billion in projects just in the Washington region.

Hall said the parks prioritize their budgets the best they can. Projects needed for public safety or historic preservation often come before more aesthetic features, like fountains.

Commercial and residential swimming pools often use chlorine to kill off algae and bacteria, but the chemical would potentially harm surrounding organisms and emit an off-putting smell, Barrett said. Since the reflecting pool is so shallow, a large amount of chlorine would be required, he said.

Ozone is nontoxic and a more ecologically sensitive method, Barrett said. In theory, a constant bubbling of ozone into the pool would oxidize and kill microalgae, he said. The algae that remain would then have to be filtered out of the pool. In time, ozone is used up and turned into oxygen.

But only time will tell if the nanobubbling system will be able to keep up with the algae blooms, Barrett said.

In some unique conditions, algae can produce toxins. These are the cyanobacteria algae blooms, sometimes called "blue-green algae," that can harm people or animals.

Mike Selckmann, associate director of aquatic habitats at the Interstate Commission on the Potomac River Basin, said the reflecting pool algae does not appear to be dangerous.

“I hesitate to put any concern, any worry, into people that this is a potential health risk,” he said. “This is just your typical algae that is just showing up in an area that is able to take advantage of a shallow, warm water system.”

"It's just unattractive," he said.