The Lincoln Memorial Reflecting Pool, which underwent a more than $14 million renovation to fix leaks and prevent algae, has developed a visible green bloom just days after being refilled.

The project was completed in early June 2026 after workers drained the 2,000-foot-long pool, repaired cracks, applied a dark “American flag blue” waterproof coating, and installed a new filtration system designed to improve water quality.

The Reflecting Pool holds approximately 6.5 million to 6.75 million gallons of water drawn from the nearby Tidal Basin. President Donald Trump promoted the renovation as a solution to years of maintenance issues, saying the upgraded landmark would be leak-free and restored to a more attractive condition.

Cleanup Efforts Begin

Shortly after the pool began refilling around June 5, green algae became visible on the water’s surface. Workers have since been removing algae by vacuuming clumps, skimming the water, and adding hydrogen peroxide as part of efforts to control the bloom.

An Interior Department spokesperson described the algae growth as “residual” material from supply lines that had remained inactive during the eight-week construction period.

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Officials said the issue was part of the normal startup process following the renovation and that the new filtration system was being used to manage water conditions.

The Ozone Nanobubbler Filtration System

The newly installed ozone nanobubbler system is designed to improve water quality by releasing extremely small ozone bubbles into the pool.

Ozone is a form of oxygen that can help break down organic materials, reduce pollutants, and limit the nutrients that allow algae to grow.

Unlike traditional filtration systems that mainly remove particles from water, ozone systems work by treating the water itself. The tiny bubbles increase contact between ozone and contaminants, allowing the system to oxidize organic matter and help maintain cleaner water.

The technology is intended to reduce the conditions that encourage algae growth, but it does not completely eliminate the possibility of algae appearing. Outdoor water features like the Reflecting Pool remain affected by weather, sunlight, temperature, wildlife, and nutrient levels.

Federal Workers o Save Lincoln Pool Project

The National Park Service has requested additional personnel to assist with the cleanup operation. Internal communications reportedly asked employees to volunteer for 12-hour shifts focused on scrubbing and pump-out operations.

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Officials classified the effort as a “regional and national priority” as crews worked through mid-June to prepare the landmark before the expected crowds for Independence Day events.

Workers wearing hip-waders have been seen removing algae from the pool as the cleanup continues.