The Lincoln Memorial Reflecting Pool in Washington, D.C., has turned green due to residual algae following a $14 million [1] renovation project.
The situation draws scrutiny to the effectiveness of the costly repairs, as the pool is one of the most photographed and symbolic landmarks in the U.S. capital.
According to reports from earlier this month, the algae surfaced as early as one day [2] after the pool was refilled. Other reports indicate the bloom appeared a few days [3] after the renovation was completed. National Park Service employees are conducting cleanup efforts to restore the water's clarity.
Interior Department and Trump administration officials said the algae was residual. This buildup occurred because supply lines sat dormant for weeks during the construction process. The growth was further exacerbated by the hot D.C. weather following the refill [4].
"It's residual," said a Trump administration official [5].
Brian Todd said the water in the Reflecting Pool is green from "residual algae" and is a work in progress as National Park Service employees help with the clean up [6].
The renovation aimed to modernize the pool's infrastructure and ensure long-term stability. However, the rapid return of the algae suggests that the dormant pipes acted as a reservoir for organic matter that triggered once the water system became active again [4].
“The water in the Reflecting Pool is green from 'residual algae'”
The recurrence of algae immediately following a multimillion-dollar investment highlights the technical challenges of maintaining historic water features. While officials attribute the bloom to dormant supply lines and ambient temperature, the timing suggests a gap between the structural renovation and the chemical stabilization of the water system.
