Workers Apply Hydrogen Peroxide to Reflecting Pool on National Mall

Workers poured multiple jugs of hydrogen peroxide into the Reflecting Pool on the morning of June 16, 2026. National Guard members deployed to the National Mall observed the application. By midday, six National Park Service workers in bright-yellow vests used long-poled tools to sweep the water.

By evening, additional workers wearing waders entered the pool with tubing and generators to pump and scrape the water. Some sections of the pool turned teal by dusk while other areas remained unchanged. The Reflecting Pool holds 4 million gallons of water.

President Trump announced in April 2026 a plan to install a blue swimming-pool liner. The administration awarded no-bid contracts to redo the base and install a nanobubbling system before the July 4 deadline. 7 million.

The system is designed to inject nanobubbles containing ozone to kill algae and break down organic material. Green Water Solutions did not respond to requests for comment. ” One worker vacuuming the pool said efforts were having an impact in the small corner where he was working.

Hans Paerl, professor of marine and environmental sciences at the University of North Carolina, stated that blue-green algae growth peaks in hot weather and that hydrogen peroxide treatment of a 4-million-gallon pool is expensive. U.S. National Office for Harmful Algal Blooms at Woods Hole Oceanographic Institution, stated that shallow warm water created ideal algae conditions and that using nutrient-poor water or sealing the system could have prevented the bloom.

Wayne Carmichael, professor emeritus of biological sciences at Wright State University, stated that the algae bloom was avoidable. ” The Harmful Algal Bloom and Hypoxia Research and Control Act reauthorization was under consideration in Congress at the time of the incident.