WASHINGTON — The Lincoln Memorial reflecting pool is once again making headlines, this week for turning green.

The Washington, D.C. landmark was refilled with water earlier this month after President Trump had its neutral grey bottom repainted “American flag blue.” The multi-million dollar project produced subtle results in the eyes of many observers, even as Trump and Secretary of the Interior Doug Burgum — whose agency managed the renovation — touted its success.

In recent days, however, the pool has taken on a verdant hue — the result of algae blooms that experts say are to be expected in these conditions.

“It’s called ‘New Pond Syndrome,’” says Steve Goodale, a Canadian swimming pool specialist known online as “Swimming Pool Steve.” “It’s a known thing that happens when you take a natural, clear body of water like this that sits in an open air environment and you try to start it up, very often you end up with green water almost immediately.”

Goodale says the process took longer — a matter of days — to unfold in this case likely due to the sheer size of the pool, which measures 2,030 feet long and has a surface area of approximately 338,000 square feet.

“Excellent conditions” for algae growth

Rosalina Stancheva Christova, a professor of aquatic ecology at George Mason University in Virginia, took water samples from the pool on Tuesday. She confirmed the algae belongs to the genus Desmodesmus, which she said is “growing in excessive amounts” but is not toxic or harmful.

Christova says this kind of common green algae is found all over the region, especially this time of year. The reflecting pool in particular provides “excellent conditions” for algae growth, she said: shallow, stagnant water, strong sunlight and no shade.

“It could happen every single summer,” she added. “But it seems that the disturbance of the pond during the renovations [is] accelerating this process.”

Christova said last month’s renovations may have affected the balance of nutrients in the pool, potentially accelerating the algae blooms. Goodale similarly views the resurfacing as one of several contributing factors.

“The new, darker interior surface is going to absorb more sunlight,” Goodale says. “It is going to result in water that’s warmer, and that ultimately is going to lead to more prolific algae growth.”

A microscopic slide shows the Desmodesmus algae that quickly turned the Reflecting Pool’s water green. The new dark blue paint of the pool’s lining makes the water warmer and friendlier to the algae growth.

Rosalina Stancheva Christova, PhD.

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Rosalina Stancheva Christova, PhD.

The Trump administration has said the algae came from residual material in supply lines that had lain dormant for weeks. Their growth was likely exacerbated by the extreme temperatures that hit D.C. last week, bringing heat index values to 95 degrees and above.

New York — In a dramatic reversal, Luigi Mangione’s legal team on Thursday backed away from a plan to use a psychiatric defense when his case goes to trial in state court in September. Mangione has pleaded not guilty to murdering health insurance CEO Brian Thompson in 2024 on a Manhattan street.

At a hearing only a day earlier before state Judge Gregory Carro, Mangione’s attorneys confirmed that Mangione had been undergoing psychiatric evaluation. They signaled that his defense would be based at least in part on the argument that Mangione was experiencing “extreme emotional disturbance.”

But in a one-line letter sent to Carro on Thursday, Mangione’s team said that “at this time” they no longer intend to introduce psychiatric evidence during the trial. It’s unclear what sparked the shift. Mangione’s team didn’t respond to NPR’s request for comment.

Former Manhattan prosecutor and legal analyst Gary Galperin told NPR it was a “stunning reversal” for Mangione to withdraw from the psychiatric defense. “One can only speculate at this point as to the reasons,” he said.

“What remains, of course, at this point is the question of what defense they will pursue at trial,” he added.

This maneuver came after Carro ordered Mangione’s attorneys to quickly share psychiatric information with prosecutors.

“They need to know what the malady is that this defendant suffers and how that triggered extreme emotional distress,” he said, during Wednesday’s hearing. “I’m not going to let you surprise people on the eve of trial. Get it done.”

Assistant Manhattan District Attorney Joel Seidemann repeatedly complained that Mangione’s team was “stonewalling” the prosecution by withholding medical information about his psychiatric state. “We have gotten nothing,” Seidemann said.

Mangione’s lead attorney Karen Friedman Agnifilo denied her team was delaying the court process or improperly withholding information.