The all-natural way to fix the Reflecting Pool (Michael J. Coren column, WaPo, June 27, 2026)

Brilliant!  Thanks to Michael J. Coren for the inspiration.  In July 1976, I briefly swam in the Reflecting Pool during the American Revolution Bicentennial.  The water had recently been cleaned and treated.  But I, for one, prefer the natural solution proposed by Mr. Coren's column. 

From The Washington Post:

The all-natural way to fix the Reflecting Pool

Enlisting nature to help clean up the algae would be more patriotic than tossing in chemicals.

June 27, 2026 at 5:00 a.m. EDTYesterday at 5:00 a.m. EDT

10 min

(Illustration by Emma Kumer/The Washington Post; iStock)

Column by Michael J. Coren

The Lincoln Memorial Reflecting Pool has predictably turned green again. No matter who is in office, no matter how much hydrogen peroxide is added, the shallow, sunbaked, nutrient-rich pool will remain an ideal home for the tiny green denizens of D.C.

Fixing the Reflecting Pool requires admitting the original mistake of the U.S. government, which built an algae farm on a former marsh.

Most politicians’ preferred response has been chemical warfare. The real answer lies in returning to our capital’s roots: Bring back the swamp.

Healthy, mature wetlands are often far cleaner and clearer than they appear. The tea-brown tint is tanninleached from fallen leaves, not muck. A balanced ecosystem of microbes and plants deprives algae of the nutrients they need to bloom.

So when I wanted to know what it would take to return the Reflecting Pool to its Edenic state, I didn’t consult swimming pool contractors. I called algae scientists, engineers and natural pool designers. 

A well-designed system of running water, gravel, microbes and wetland plants, they told me, could deliver crystal-clear water free of visible algae. It would slash the need for chemicals, electricity and maintenance in the troubled basin. We could even make it swimmable.

The technology is as old as life, and as modern as the thousands of natural pools and swimming pondssuccessfully installed around the world from Minnesota to Germany.

The national Reflecting Pool debacle has captured Americans’ attention because it distills so much about our the nation’s dysfunction: grandiose ambitions; minimal planning, overpriced quick fixes; and catastrophic outcomes followed by deflection or denial of responsibility by those in charge. Rehabilitating the pool to reflect the Potomac Mudflats’ original glory would help rejuvenate, in some small way, the country’s faith in itself. 

This will not happen by the nation’s 250th birthday. The Interior Department declined to answer questions about whether it would consider a more natural approach. 

But an administration brave enough to do so could make the Reflecting Pool a turning point for the U.S. government’s posture toward the natural world. We can enlist nature as an ally rather than fight it to the death in a war we can’t win.

What could be more patriotic than a system designed by America’s best engineers and ecologists, yet inspired and managed by the original inhabitants of America’s capital — its microbes, plants and wildlife?

Forget draining the swamp. Restore it. Here’s how.

An alligator prowls the waters in the Big Cypress National Preserve in Florida. (Robert F. Bukaty/AP)

Nature undefeated

Algae are remarkable organisms. The photosynthetic bacteria, protists and other microbes are found in all waters of the world, from the smallest ponds to the biggest oceans, said Pat Glibert, a phytoplankton ecologist who studies algal blooms at the University of Maryland.

While no bigger than the width of a human hair, they turn sunlight, nutrients and water into life itself. About half the oxygen we breathe, and the foundation of the aquatic food chain, are thanks to algae. Without them, we wouldn’t be here.

These ecological workhorses can double their biomass in a day given the right conditions, such as a shallow basin of warm, nutrient-rich water — almost exactly what was built to honor Abraham Lincoln. “The fact that there is a bloom does not surprise me,” Glibert said. “It’s ideal growing conditions.”

Controlling algae by killing it in an enclosed body of water is a bit like pulling up the weeds from your garden, scattering their seeds around and then tossing fertilizer on top. Chemicals used to kill algae burst their cells, releasing organic matter back into the water: the perfect nutrient mix for growing new algae (as well as that scum National Park Service employees are always vacuuming out of the pool).

Healthy, mature wetlands are often far cleaner and clearer than they appear. The tea-brown tint is tanninleached from fallen leaves, not muck. A balanced ecosystem of microbes and plants deprives algae of the nutrients they need to bloom.

So when I wanted to know what it would take to return the Reflecting Pool to its Edenic state, I didn’t consult swimming pool contractors. I called algae scientists, engineers and natural pool designers. 

A well-designed system of running water, gravel, microbes and wetland plants, they told me, could deliver crystal-clear water free of visible algae. It would slash the need for chemicals, electricity and maintenance in the troubled basin. We could even make it swimmable.

The technology is as old as life, and as modern as the thousands of natural pools and swimming pondssuccessfully installed around the world from Minnesota to Germany.

The national Reflecting Pool debacle has captured Americans’ attention because it distills so much about our the nation’s dysfunction: grandiose ambitions; minimal planning, overpriced quick fixes; and catastrophic outcomes followed by deflection or denial of responsibility by those in charge. Rehabilitating the pool to reflect the Potomac Mudflats’ original glory would help rejuvenate, in some small way, the country’s faith in itself. 

This will not happen by the nation’s 250th birthday. The Interior Department declined to answer questions about whether it would consider a more natural approach. 

But an administration brave enough to do so could make the Reflecting Pool a turning point for the U.S. government’s posture toward the natural world. We can enlist nature as an ally rather than fight it to the death in a war we can’t win.

What could be more patriotic than a system designed by America’s best engineers and ecologists, yet inspired and managed by the original inhabitants of America’s capital — its microbes, plants and wildlife?

Forget draining the swamp. Restore it. Here’s how.

An alligator prowls the waters in the Big Cypress National Preserve in Florida. (Robert F. Bukaty/AP)

Nature undefeated

Algae are remarkable organisms. The photosynthetic bacteria, protists and other microbes are found in all waters of the world, from the smallest ponds to the biggest oceans, said Pat Glibert, a phytoplankton ecologist who studies algal blooms at the University of Maryland.

While no bigger than the width of a human hair, they turn sunlight, nutrients and water into life itself. About half the oxygen we breathe, and the foundation of the aquatic food chain, are thanks to algae. Without them, we wouldn’t be here.

These ecological workhorses can double their biomass in a day given the right conditions, such as a shallow basin of warm, nutrient-rich water — almost exactly what was built to honor Abraham Lincoln. “The fact that there is a bloom does not surprise me,” Glibert said. “It’s ideal growing conditions.”

Controlling algae by killing it in an enclosed body of water is a bit like pulling up the weeds from your garden, scattering their seeds around and then tossing fertilizer on top. Chemicals used to kill algae burst their cells, releasing organic matter back into the water: the perfect nutrient mix for growing new algae (as well as that scum National Park Service employees are always vacuuming out of the pool).

“You’re fighting a losing battle,” Glibert said. It’s one the federal government has waged for a century.

Constructed on dredged Potomac marshland, the Reflecting Pool was paved with asphalt-and-tile and later, in the 1980s, with concrete. From its opening, the pool had leaks and poor water quality as it settled into the soft, marshy land below. By the 2010s, it was losing more than half a million gallons per week. When the basin was finally reconstructed in 2012, nearly all the changes were a gift to the algae. 

Engineers made it shallower, just 18 to 30 inches deep, and switched the water source from city drinking water to the nutrient-rich Potomac-fed Tidal Basin. A treatment plant was installed to recirculate up to about 1.7 million gallons a day, but the nutrients weren’t filtered out before the water returned to the pool. Most recently, the Trump administration’s decision to paint the pool a darker, sunlight-absorbing “American Flag Blue,” gave the algae a nutrient-rich hot tub.

Truly eradicating the algae with chemicals would be prohibitively expensive or potentially dangerous to everything near the pool, humans included. Even then, it would attack the symptom, not the cause: the nitrogen and phosphorus the algae feed on. The only durable fix is removing them.

To figure out how, I called the people who’ve spent three decades building swimming pools that work like ponds.

Heroic biofilm

James Robyn heeded the call of the family pool business in New Jersey in 1980, leaving behind a career in corporate computing. After three decades building conventional, chlorinated pools, he brought BioNova, a European natural-pool system, to the U.S. in 2007. He was later joined by Allen Schnaak, who came out of retirement from selling pool chemicals for three decades to build pools that clean water by growing life, not killing it.

I asked them if they could turn the Reflecting Pool into a chemical- and algae-free oasis in the middle of the nation’s capital.

“Could it be made into a natural pool? Sure,” Schnaak replied. “It’s not anything we’re inventing. All we’re doing is replicating the same environments that occur in nature: a stream with fast-moving water.”

Natural pool firm Bionova created AI-assisted renderings of the Lincoln Memorial Reflecting Pool with natural filtration systems. (Courtesy of Bionova)

Water is alive. Rather than scrubbing it with chlorine, BioNova builds an ecosystem that creates the conditions for “gin-clear” water, Schnaak told me, like a running creek. “People begin chasing their tails when they start asking about how do you get rid of algae,” he said. “You don’t get rid of algae. What you do is you do not extend an invitation for it to come and stay. It will not grow if it doesn’t have anything to eat. That’s it. Cut the nutrients off.”

Bionova does that by retrofitting otherwise conventional pools with living ecosystems that strip water of the nutrients algae need.

One design is a biofilter: a small engineered wetland of plants, gravel and slow-moving water, where the plants take up the nitrogen and phosphorus directly. The second is a bioreactor: a tank or trench with gravel, usually limestone, covered by a biofilm of microorganisms that pull the same nutrients out of the water. Imagine the slick coating on a green river rock eating the algae’s lunch.

You don’t have to look far to see them in action. In north Minneapolis, the Webber Natural Swimming Poolis the first public natural swimming pool in North America to ditch chemicals. Since opening in 2015, the pool’s half-acre swimming zone (filtered by 7,000 aquatic plants rooted in layers of limestone and granite gravel) has welcomed thousands of people into its clean, clear water. Europe has taken the idea further and has more than 20,000 public and private natural swimming pools. The world’s first public natural swimming pool opened in Austria in 1990.

Is achieving such clean water possible on the National Mall? 

For a reality check, I asked Mick Hilleary of Total Habitat, which has built more than 80 natural pools around the world, including in unforgiving environments from India to Florida.

“It could be done,” he said. “It’s a tough challenge for biological filtering — and any other type, for that matter — because it’s so large and very shallow.” The ultimate solution, he speculated, would combine multiple approaches, including conventional and biological filters. “I enjoy a challenge,” Hilleary said, “and this is the biggest one I’ve seen lately.”

How much would it cost to fix the Reflecting Pool? BioNova wouldn’t offer an exact quote. “We’re not looking for this job,” Robyn said, but he ventured it would be in the “tens of millions,” an investment that would probably last much longer than President Donald Trump’s recent $14 million paint and resurfacing job.

Properly designed, as the rendering from BioNova shows, it could even enhance the original design intended to “recede beneath reflections of sky, trees and stone.” We could call it the Reflecting Swamp.

I’ll be crystal clear: I don’t know if this approach would work. What I do know is that the current strategy has not survived contact with reality, and unless we try something different, we will fail, over and over again.

The United States isn’t known for learning quickly from its mistakes. There’s an apocryphal line from Winston Churchill that Americans will always do the right thing, after they’ve tried everything else.

Well, we’ve tried everything else. The U.S. is engaged in asymmetric warfare with enemies, on multiple fronts, that have us surrounded and show no signs of surrendering.

It’s time to sign a truce with nature. Our alleged enemy will gladly switch sides and clean up the expensive mess we’ve made. All it asks in return is a marshy, ground-level condo on the nation’s front lawn. Then we can begin to restore not only the Reflecting Pool but, just maybe, our national relationship with a living world we depend on far more than it depends on us.

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The comments on the article discuss various perspectives on addressing the algae problem in the Reflecting Pool, with many suggesting natural solutions like using aquatic plants or creating a more ecological environment. Several comments criticize the current administration,... Show more

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