Reflecting Pool renovation faces algae and peeling sealant

President Donald Trump’s renovation of the Lincoln Memorial Reflecting Pool is facing new problems weeks after the landmark was refilled: algae turned the water green, crews poured hydrogen peroxide into the pool, and sections of the new blue surface have begun to peel.

The project, launched ahead of America’s 250th anniversary celebrations, was meant to address leaks, algae and plumbing problems at the century-old pool. Trump said in April he would make the pool “beautiful” and “the way it’s supposed to be,” after criticizing it as “filthy” and “dirty.” He personally selected an “American Flag Blue” sealant for the pool floor, describing it as the “latest and greatest filament” and an “industrial-grade” version of a swimming pool liner.

Federal contract records show the project has grown well beyond Trump’s initial estimate of under $2 million. NBC News reported that the cost has topped $14.6 million, while CBS News said federal contracts were valued at more than $14 million. NPR reported the government is paying $1.7 million to an Ohio-based company for nanobubble technology alone.

After the pool was refilled earlier this month, algae appeared in the water. The Interior Department told CBS News the outbreak was “part of the normal startup process” and came from “residual algae from the supply lines which have been sitting dormant for eight weeks while construction has been taking place.” The department said workers were cleaning it out.

Scientists told NPR the bloom was not surprising. Rosalina Stancheva Christova, a George Mason University aquatic ecology professor who sampled the water Tuesday, identified the algae as Desmodesmus and said it was “growing in excessive amounts” but was not toxic or harmful. She said the shallow, stagnant, sunlit pool provides “excellent conditions” for algae growth and that the renovation may have accelerated the bloom.

Steve Goodale, a swimming pool specialist known online as “Swimming Pool Steve,” called the episode “New Pond Syndrome.” He said the darker surface could absorb more sunlight, warming the water and encouraging algae. “It’s a known thing that happens when you take a natural, clear body of water like this that sits in an open air environment and you try to start it up,” he said.

Crews have used hydrogen peroxide to kill the algae and deployed what the Interior Department called “high-tech nanobubble ozone technology.” The department said hydrogen peroxide is milder than chlorine and has “no harmful side effects to marine life or to the environment.” On Wednesday, the department posted on X that the nanobubble system had “very effectively killed the algae” and that National Park Service workers were vacuuming dead algae from the bottom. It said the water was “crystal clear.”

But reporters and visitors continued to see green water and visible algae along parts of the pool this week. NBC News and NPR also observed sections of the blue coating peeling from the pool floor, with strips floating under the water. CBS News reported that a tear was spotted Thursday in part of the applied material. The Interior Department did not respond to NBC News’ request for comment Friday; CBS News said it had sought more information.

The Reflecting Pool has struggled with algae, leaks and maintenance problems for years. It underwent a more than $30 million renovation early in the Obama administration, but algae blooms and other issues continued. NPR reported that after the pool reopened from that renovation in 2012, the National Park Service had to drain and refill it and recalibrate ozone levels. In 2019, crews drained four million gallons to repair a broken water line with algae growing in it.

White House spokesperson Taylor Rogers told NPR, “Thanks to President Trump, new lining and industrial grade materials will permanently seal the Reflecting Pool, which previously leaked 16 million gallons per year and wasted countless taxpayer dollars.”