AMP Article

The science behind the algae bloom in Trump’s Reflecting Pool revamp

Published June 24, 2026 · Updated June 24, 2026 · By Charles Taylor

The Algae Dilemma in Trump's Reflecting Pool Revamp

The science behind the algae bloom - Months after President Donald Trump unveiled plans to modernize the Lincoln Memorial Reflecting Pool, the project has taken an unexpected turn. While the goal was to eliminate leaks and restore the iconic water feature to its original blue hue, the pool now appears green due to an algae bloom. This issue has sparked questions about the effectiveness of the recent renovations and the scientific factors contributing to the problem.

The Renovation Project and Its Hurdles

Announced in April, the project aimed to address long-standing issues with water quality and structural integrity in the Reflecting Pool. Trump’s team emphasized the need to repaint the pool’s bottom with "American Flag Blue" to enhance its visual appeal. However, despite the work being declared complete by June 9, the pool has since developed a noticeable green tint, raising concerns among observers.

Two firms were contracted for the project: Atlantic Industrial Coatings and Green Water Solutions. Atlantic Industrial Coatings received $14.2 million for resurfacing the pool, while Green Water Solutions was awarded $1.7 million to improve water quality. The decision to award no-bid contracts has drawn scrutiny, with some suggesting ties to Trump donors and local business interests.

Scientific Insights into the Algae Bloom

Patricia Glibert, a professor at the University of Maryland’s Center for Environmental Science, explained the underlying causes of the algae growth. "Algae require three key elements: sunlight, nutrients, and time," she noted. "Nitrogen and phosphorus, essential for cellular development, are naturally present in water. When combined with sunlight and warmth, algae can proliferate rapidly."

“Add some sunlight and heat, and the algae will start to grow,” Glibert said. "They can double in biomass every day, leading to a massive bloom within a week or two."

Glibert highlighted that the pool’s dark-colored floor might be exacerbating the issue. "Darker surfaces absorb more heat, which can accelerate algae growth," she explained. "While this is one factor, it’s not the sole cause. The water depth and nutrient levels also play a significant role."

Water depth, she pointed out, affects how light penetrates the pool. "In shallow systems, like the Reflecting Pool, sunlight can reach the bottom, creating ideal conditions for algae to thrive," Glibert said. "This is a common challenge in aquatic environments, where light and nutrients are abundant."

Treatment Efforts and Ongoing Challenges

Since the algae bloom was noticed, workers have been applying hydrogen peroxide to combat the issue. However, Glibert cautioned that this method only addresses the immediate problem. "Hydrogen peroxide kills algae on contact, but it doesn’t prevent new growth," she said. "The dead algae sink to the bottom, decay, and release nutrients back into the water, perpetuating the cycle."

To fully resolve the problem, Glibert recommended a multi-pronged approach. "Continuous monitoring of water chemistry is crucial, along with improved filtration systems and treatments like algaecides or nano-bubbler technology," she added. "Without these measures, the algae bloom will likely return."

Despite these recommendations, the pool’s basin is set to be drained again to tackle the issue. This process has already revealed that certain sections require repairs, suggesting that the initial renovation may have overlooked critical design factors. The Interior Department, which oversees the pool, previously stated that algae blooms have been a recurring problem since the pool’s reopening in 1922, indicating a pattern that extends beyond Trump’s recent efforts.

Historical Context and Previous Attempts

The Lincoln Memorial Reflecting Pool has a long history of maintenance challenges. Over the decades, multiple attempts to address its water quality issues have been made, yet algae blooms persist. According to the Interior Department, the pool has faced recurring algae problems during every major overhaul, with solutions often proving temporary.

One notable example was the Biden-era plan to replace the granite lining, which Trump rejected in favor of a cheaper, faster alternative. His decision to sandblast, caulk, and resurface the pool rather than fully replace it has been criticized for potentially compromising long-term water quality. Trump himself has since attributed the current issues to vandalism, drawing attention to the costs of past renovation efforts by former presidents.

Broader Implications and Public Reaction

The algae bloom has become a focal point for public scrutiny, with images of the green pool circulating widely by June 18. While the initial plan was to restore the pool to its former glory, the visible green tint has raised doubts about the project’s success. Analysts suggest that the combination of environmental factors and maintenance practices has created a perfect storm for algae growth.

Experts warn that the pool’s condition is a microcosm of broader challenges in maintaining large water features. "Algae blooms are a natural occurrence in water bodies, but they can become problematic when nutrients are concentrated or circulation is inadequate," Glibert said. "This is especially true in structures like the Reflecting Pool, where historical and structural elements contribute to the issue."

The current situation has also sparked discussions about the effectiveness of the chosen contractors. Green Water Solutions, responsible for water quality improvements, has been linked to Trump donors, prompting questions about the oversight in the project. Meanwhile, Atlantic Industrial Coatings, which handled the resurfacing, has yet to provide detailed updates, leaving uncertainties about the long-term viability of the repairs.

Looking Ahead: A Call for Sustainable Solutions

As the pool awaits its next draining, there is a growing consensus that a more comprehensive strategy is needed. Glibert emphasized that algae blooms are not just an aesthetic concern but a sign of underlying water chemistry imbalances. "This isn’t just about the color of the pool—it’s about the health of the entire ecosystem," she said.

Experts suggest that integrating modern filtration systems and regular nutrient monitoring could prevent future blooms. Additionally, the use of algaecides or nano-bubbler technology might offer a more durable solution. However, without sustained investment and careful planning, the Reflecting Pool may continue to face the same issues that have plagued it for over a century.

For now, the algae problem serves as a reminder of the complexities involved in maintaining iconic landmarks. While Trump’s vision for the pool was ambitious, the current green hue highlights the challenges of balancing cost, efficiency, and environmental sustainability in large-scale projects. As the pool undergoes its next phase of repairs, the public will be watching closely to see if the issues can finally be resolved.