National Park Service crews poured hydrogen peroxide into the Lincoln Memorial Reflecting Pool on June 16, 2026 [1], to combat a sudden algae bloom.
The timing of the treatment is critical as officials aim to restore the water's clarity before the July 4 celebrations. The bloom appeared shortly after the pool underwent an expensive repainting project, raising concerns about the long-term maintenance of the landmark.
Work crews targeted the algae growth on Tuesday [1]. The bloom developed following a period of warm weather and the recent completion of a $14 million repainting project [2]. The pool, located on the National Mall in Washington, D.C., is one of the most photographed sites in the U.S.
While some reports specify the use of hydrogen peroxide [1], other accounts suggest the National Park Service is employing a variety of methods to kill the bloom, including the use of nanobubbles [3]. The agency has not detailed the specific concentration of chemicals used in the process.
Algae blooms in the pool have been a recurring issue for the National Park Service. The recent $14 million investment [2] was intended to modernize the pool's infrastructure and improve its appearance, yet the combination of heat and stagnant water continues to trigger these biological growths.
Maintenance teams are working to ensure the water returns to its signature mirror-like quality. The process involves treating the water to eliminate the green hue caused by the algae before the anticipated surge of tourists for the Independence Day holiday.
“Crews poured hydrogen peroxide into the Lincoln Memorial Reflecting Pool on June 16, 2026.”
The recurrence of algae blooms immediately following a multi-million dollar renovation suggests that infrastructure upgrades alone may not be sufficient to counter environmental factors. As warm weather patterns persist, the National Park Service may need to shift from periodic chemical treatments to more sustainable, long-term biological or mechanical filtration systems to maintain the site's aesthetic integrity.
