Lincoln Memorial Reflecting Pool Turns Green Amid Algae Bloom and Cleanup

The Reflecting Pool at the Lincoln Memorial in Washington, D.C., has turned a vivid green due to an algal bloom of the genus Desmodesmus. The growth follows a recent renovation that repainted the pool’s interior a darker shade, which absorbs more sunlight and heats the shallow water, creating ideal conditions for algae. Experts say the algae are not toxic, but officials are treating the water with hydrogen peroxide and ozone nanobubble technology to restore the traditional blue appearance before the July 4 Independence Day celebrations.

President Donald Trump has framed the discoloration as vandalism, posting on Truth Social that “we have had serious problems of vandalism in the beautiful Reflecting Pool.” Authorities arrested former Olympic cyclist David Hearn, who maintains he merely touched the water and “did not destroy, break or tear anything.” Workers continue to employ nanobubble generators and vacuum equipment to remove dead algae and regain the pool’s historic look.