Newly renovated Reflecting Pool is already fighting an old problem

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Newly renovated Reflecting Pool is already fighting an old problem

Less than two weeks after reopening from a Trump-backed renovation, the Lincoln Memorial Reflecting Pool is being treated for a widespread algae bloom that has turned large portions of the water green.

National Park Service crews spent Tuesday vacuuming algae from the pool and adding hydrogen peroxide to the water, while Interior Department officials defended a renovation project that was supposed to deliver a cleaner, leak-free reflecting pool ahead of the nation’s 250th birthday celebrations next month.

Crews move quickly after algae spreads

The pool was refilled earlier this month after a renovation that included leak repairs, a new filtration system and a blue liner that President Donald Trump promoted as a major upgrade to one of Washington’s most recognizable landmarks.

Algae showed up almost immediately.

By Tuesday, crews were using a combination of ozone-based filtration and hydrogen peroxide treatments to get the bloom under control. Interior officials said the algae had already been killed and that workers were focused on removing it from the water.

U.S. National Park Service employees use a vacuum pump to clean algae off the bottom of the newly repainted Lincoln Memorial Reflecting Pool on the National Mall on June 16, 2026 in Washington, DC. (Photo by Chip Somodevilla/Getty Images)

“Due to deploying the advanced nanobubbler technology, the algae is dead and being vacuumed up as we speak,” an Interior Department spokesperson told CNN.

The administration has argued the algae originated in water that sat stagnant inside supply lines during construction and was carried into the pool when it was refilled.

The filtration system itself was a key part of the renovation. Interior officials say the ozone-injected nanobubbler technology was installed specifically to combat contaminants, pathogens and the algae problems that have repeatedly plagued the reflecting pool.

A problem that outlived multiple renovations

The algae bloom may be new, but the problem is not.

The reflecting pool underwent a major restoration during the Obama administration in 2012. That project cost roughly $34 million and was intended to address many of the same issues, including leaks, stagnant water and recurring algae growth. Within weeks of reopening, algae had returned.

The Washington Monument is seen in distance as workmen finish up the final stages of the Reflecting Pool restoration project August 13, 2012, in Washington, DC. (Photo credit should read PAUL J. RICHARDS/AFP/GettyImages)

Several experts told CNN and Politico that the basic conditions that allow algae to thrive remain difficult to overcome in a shallow body of water that sits in the summer heat.

Brooks Barrett, an algae specialist at the Smithsonian’s National Museum of Natural History, said removing the current bloom will not eliminate the need for constant management.

“It would be an ongoing filtration management thing going on,” Barrett told CNN.

Former National Park Service regional director Kym Hall was even more direct.

“If this problem could have been easily solved or cheaply solved, somebody would have freaking done it,” Hall told Politico.

A $14 million fix meets a familiar challenge

Trump made the reflecting pool renovation a personal priority this year, frequently criticizing its appearance and promising a cleaner, more attractive landmark before the July 4 celebrations.

The project’s cost ultimately climbed above $14 million, according to federal spending records cited by multiple news outlets. In addition to repairs and filtration upgrades, the administration coated the bottom of the pool with what Trump called an “American Flag Blue” liner.

A view of the application of blue sealant onto the bottom of the Lincoln Memorial Reflecting Pool on the National Mall is seen from the Washington Monument on May 29, 2026 in Washington, DC. (Photo by Heather Diehl/Getty Images)

“We made the surface as good as it can be,” Trump said in May. “No leaks. No problems.”

The renovation also drew criticism from preservation groups that objected to the color change and from watchdogs who questioned the project’s cost and contracting process.

Interior officials maintain the work addressed long-standing structural issues and insist the new filtration system will produce cleaner water over time.


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Ella Rae Greene, Editor In Chief

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