WASHINGTON, D.C. — The Lincoln Memorial Reflecting Pool developed an algal bloom, turning its water green, shortly after a renovation project that included painting the bottom American flag blue. The renovation contracts totaled at least $14.8 million.

President Donald Trump stated the renovation project cost approximately $10 million. An Interior Department spokesperson said, "Unlike under Obama and Biden, the National Park Service is actually maintaining the beautifully completed Reflecting Pool." The spokesperson added, "There are no harmful side effects to marine life or to the environment."

National Park Service employees and contractors deployed hydrogen peroxide, ozone nanobubbles, and other chemicals to address the algae. Workers used a swimming pool vacuum to remove algae from the painted bottom. The pool receives its water from the Tidal Basin. Algae has been present at the site since it opened more than one hundred years ago. The Centers for Disease Control and Prevention states that shallow manmade bodies of water are prone to algal growth when warm, exposed to sunlight, and containing nutrients such as nitrogen and phosphorus.

Cochise Wanzer II, president of the Pool Service Company, commented on the situation. Wanzer said, "You’re basically taking natural, untreated river water, pumping it in and expecting it to do something different from what it would do out in the open." He also stated that the newly painted dark bottom contributes to the algal growth. He said, "Now that the bottom is nice and dark, it elevates the temperature and the algae grows better."

The Cultural Landscape Foundation filed a lawsuit against the Trump administration in May to block the renovation. Alexander Kristofcak, an attorney for the plaintiffs, said, "The dark grey, achromatic basin was not incidental to the design. It was the design." Interior Secretary Doug Burgum stated that the administration followed all required bidding rules for the project.

No independent assessment was available for this report.