The scene unfolded just days after President Donald Trump ordered a multimillion-dollar renovation of the iconic pool, demanding clear water and a bottom painted “American Flag Blue” in time for the nation’s 250th birthday celebrations this summer.
The algae began forming last week, almost immediately after contractors completed the work. An Interior Department spokesperson said Friday that the agency would remove the growth and deploy “nanobubblers” to keep the water clear, but the bloom has spread rapidly since then. On Tuesday morning, machinery bearing the label of Green Water Solutions, an Ohio-based contractor paid $1.7 million by the National Park Service to install an ozone nanobubbling system, pumped foam into the pool while a worker from Pearl Purity Water Solutions vacuumed algae off the bottom.
Brooks Barrett, a researcher who studies marine plant life at the Smithsonian Institution, said the pool’s design makes it especially vulnerable. “The reflecting pool is perfect for algae. If you were trying to biofarm algae, this would be the way to go. It’s warm, it’s stagnant, it’s perfect,” Barrett said, adding that there is “no quick fix” for the bloom.
Visitors from outside Washington who had seen reports of the algae said they were surprised by how widespread it had become. The Interior Department said Tuesday it is working to kill the algae using the nanobubbling system and hydrogen peroxide, which officials described as a milder treatment than chlorine that is commonly used in spas and natural swimming pools. The department said the hydrogen peroxide would have no harmful effect on marine animals or the environment.
Renovation and Recurrence
The renovation was ordered by Trump to address leaks and improve the pool’s appearance ahead of large Independence Day events on the National Mall marking the country’s 250th anniversary. The president had specified that the pool’s bottom be painted “American Flag Blue,” the color of a commercial-grade swimming pool liner. But within days of completion, the water turned green.
Green Water Solutions did not respond to a request for comment. Pearl Purity Water Solutions, which has treated water in the pool since 2021, could not be reached. The National Park Service said in a statement that it is “maintaining the beautifully completed Reflecting Pool” and deploying high-tech nanobubble ozone technology to keep the water “not only crystal clear but also clean.”
Barrett’s assessment, however, suggests the challenge may persist. With warm temperatures and stagnant water, the pool offers ideal conditions for algae to thrive, and the recent renovation has not altered those fundamental factors. Whether the nanobubbling system and hydrogen peroxide can reverse the bloom before the July celebrations remains an open question.
