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Days after the completion this month of a $14 million renovation, the shallow water in the Lincoln Memorial’s Reflecting Pool had more algae in it than at any recorded point in the month of June for at least five years, according to a specialized analysis of satellite data.
President Donald Trump vowed in April to clean up what he called the “filthy” and “disgusting” water in the Reflecting Pool. He promised to resurface the basin to eliminate persistent leaking and to paint it “American flag blue.” Once the pool started to be refilled, on June 4, he praised its “clean, beautiful water.”
At The Washington Post’s request, Alana Menendez, a postdoctoral researcher at the University of Virginia’s Department of Environmental Sciences, analyzed light-reflectance data from a European satellite called Sentinel-2. The satellite captures clear images of the Reflecting Pool several times a month, and the data it produces can be used to estimate the presence of chlorophyll-a, a pigment found in algae.
A higher value of that metric, known as the normalized difference chlorophyll index (NDCI), points to more algae in the water, Menendez said.
Menendez’s analysis detected more algae in the reflecting pool in an image taken Saturday — in the week after it reopened — than in any June images going back to 2021. The algae level was among the highest measured in any month in the past two years, according to the analysis.