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Crews battle algae bloom in Washington’s newly repainted Reflecting Pool

By Thomson Reuters Jun 16, 2026 | 4:46 PM

By Ryan Patrick Jones

June 16 (Reuters) – 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.

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.

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.

“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 on ⁠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.”

(Reporting by Ryan Patrick Jones in Toronto; Editing by Caitlin Webber ​and Bill Berkrot)