Reflecting Pool turns green with algae after Trump renovation

The Lincoln Memorial Reflecting Pool was refilled on June 5, and by June 15 the water had turned green with algae. What was meant to be a polished reset for one of the National Mall’s most recognizable landmarks instead became a public example of how quickly a shallow urban basin can shift from mirror-like icon to nutrient-rich bloom.

President Donald Trump had pushed the renovation ahead of the nation’s 250th anniversary celebration, describing the pool as a “dirty disgusting place” and saying the work would cost up to $2 million and last “30, 40, 50 years.” Later estimates put the project far higher, rising to about $14 million and then $16 million as more repairs were added. Administration officials and the National Park Service kept treating the pool, vacuuming dead algae and planning additional work around the July 4 holiday.

The green water was not just a visual shock. Testing reported by CNN found phosphate levels far above what is recommended to keep algae in check, and a Slate analysis identified the dominant organism in a sample as Desmodesmus, a green algae that feeds on phosphorus and nitrogen. Experts pointed to the usual ingredients for a bloom: stagnant water, sunlight, warm weather and excess nutrients. In that sense, the Reflecting Pool looked less like a failed monument than a textbook case of what happens when a large, shallow water feature is managed with less chemical intervention and more ecological realism.

The problem also had history. The Reflecting Pool has shown algae before, with reports noting greenish water visible in Getty photos from April, June and August 2006. ABC News reported that the new “American flag blue” liner or sealant installed at the bottom of the pool appeared to be peeling or falling apart, adding to the sense that the renovation was already under strain.

The dispute spilled onto the National Mall itself. CBS News reported that U.S. Park Police arrested five people and issued five federal citations after Trump claimed the pool had been vandalized. The Washington Post said demonstrators leaned into the absurdity, chanting, “Let’s grow algae, let’s grow.” For a site built to project permanence and national order, the Reflecting Pool instead exposed a familiar tension: postcard aesthetics are expensive, and so is pretending a sunlit, nutrient-rich basin can be kept pristine forever.