WASHINGTON — Work crews poured hydrogen peroxide into the newly repainted Lincoln Memorial Reflecting Pool on Tuesday to combat an algae bloom, a little over a week after it was repainted as part of President Donald Trump's campaign to revamp some of Washington's major monuments.
The Lincoln Memorial Reflecting Pool appears green Tuesday in Washington after recent renovations that followed a directive from President Donald Trump to paint it blue ahead of the 250th anniversary of U.S. Independence.
National Park Service workers were seen emptying jugs labeled "12% hydrogen peroxide" into the visibly green water of the nearly century-old basin that stretches between the Lincoln Memorial and the Washington Monument on the National Mall.
A spokesperson for the Interior Department said the pool is being treated with "high-tech nanobubble ozone technology" that kills algae, pathogens including E. coli, and other contaminants. The department said hydrogen peroxide is also being used, saying it's "a milder treatment than chlorine" that is used in spas and natural swimming pools.
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Christopher Gobler, a professor at Stony Brook University in New York who has studied harmful algal blooms for more than 30 years, said hydrogen peroxide is a common short-term treatment for algae that is not likely to have major health effects on the ducks and geese that frequent the pool.
U.S. National Park Service workers dump bottles of hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday in Washington, part of efforts to mitigate an algae bloom.
"It's most harmful to animals that are 100% in the water," Gobler said, adding the chemical can create low oxygen conditions that can be lethal to fish.
It might not be a long-term fix, though, he warned.
"There's always going to be a rebound of the algae," Gobler added. "Hopefully it works as a quick fix, but these algae do tend to rebound."
The reflecting pool was refilled with water starting June 5 as part of a renovation project directed by Trump that involved draining, cleaning and resurfacing it.
The bottom of the pool was repainted in a color Trump calls "American flag blue."
Chemical poured into Lincoln Memorial Reflecting Pool
Crews clean up algae Monday, June 15, 2026, that began to grow in the Lincoln Memorial Reflecting Pool days after the Trump administration’s at least $13 million renovation project that repainted the surface “American Flag Blue."
Crews clean up algae Monday, June 15, 2026, that began to grow in the Lincoln Memorial Reflecting Pool days after the Trump administration’s at least $13 million renovation project.
People visit the Lincoln Memorial Reflecting Pool on Monday, June 15, 2026, in Washington as National Park Service workers use skimmers to clean algae.
Ducks swim Monday, June 15, 2026, in the green waters of the Lincoln Memorial Reflecting Pool in Washington.
National Park Service workers use skimmers to clean algae Monday, June 15, 2026, from the Lincoln Memorial Reflecting Pool in Washington following the completion of recent renovations.
National Park Service workers use skimmers to clean algae from the Lincoln Memorial Reflecting Pool on Monday, June 15, 2026, in Washington after the completion of recent renovations.
A couple sits Monday, June 15, 2026, on the edge of the Lincoln Memorial Reflecting Pool in Washington.
Algae appears Monday, June 15, 2026, in the Lincoln Memorial Reflecting Pool in Washington after the recent completion of renovations.
National Park Service workers use skimmers to clean and pump algae-filled water from the Lincoln Memorial Reflecting Pool on Monday, June 15, 2026, in Washington.
U.S. National Park Service workers dump bottles of hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington as part of efforts to mitigate an algae bloom.
U.S. National Park Service workers dump bottles of hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington.
A U.S. National Park Service worker dumps jugs of hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington.
Foam floats on the surface of the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington as U.S. National Park Service workers dump in bottles of hydrogen peroxide.
U.S. National Park Service workers dump bottles of hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington.
A duck swims Tuesday, June 16, 2026, as a U.S. National Park Service worker dumps bottles of hydrogen peroxide in the Lincoln Memorial Reflecting Pool in Washington.
A U.S. National Park Service worker dumps hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington.
National Park Service workers dump bottles of hydrogen peroxide in the Lincoln Memorial Reflecting Pool on Tuesday, June 16, 2026, in Washington.
