by Kate Yandell

ANALYSIS — President Donald Trump has repeatedly blamed vandals for damaging the new blue lining of the Lincoln Memorial Reflecting Pool, which is now peeling, as well as for algae in the water. But the administration has not provided evidence to back up the president’s claims. Experts say the pool’s ills have a variety of plausible explanations that do not involve intentional harm.

Installing linings on pools and making sure they properly adhere is challenging, experts in pools and waterproof coatings have told news outlets, and improper surface prep or water intrusion can cause peeling, they said. Meanwhile, algae would be expected in a shallow, still, unshaded pool fed by nutrient-rich water that had been painted dark blue, Steven Chapra, a water quality modeler and professor emeritus at Tufts University, told us.

Despite these competing explanations, Trump has repeatedly asserted that vandals are to blame. “You know, we have 100- … I think 290-, 300-foot slit right through it,” Trump said at a June 22 press event, after news reports surfaced of blue pieces of the pool’s lining separating from the bottom. “Probably a box cutter or a knife of some kind.”

He claimed at the same event that someone may have put fertilizer in the pool, part of a series of claims that someone had poured in some substance or chemicals. “They did something to create the algae,” he said.

Trump’s comments on vandals cutting the pool’s coating with a knife echoed theoretical statements he had made on May 4, before reports of damage to the pool. “It’s very strong. You couldn’t — if you had a knife — I don’t want to give anybody ideas,” he said, referring to the pool’s new coating. “If you had a knife, you can’t even cut it, so strong, so powerful.”

The president has since spoken or posted about alleged cuts in the pool at least daily, with the “gash” — or “numerous slashes” — growing to cover a length of 350 feet and the possible implements used including “a very sharp knife or razors.”

On June 24, Trump posted a photo of the dark blue bottom of the empty pool, stating, “This is the hard rubber surface — No Paint — Before the Vandals cut and pulled it apart!” That same day, he specified that the vandals had gone to the “bottom” and “started ripping it up,” as well as cut “this very expensive stuff” at the “side of the pool right at water level.”

The White House replied to our request for more information on the vandalism with a June 25 press release claiming to have surveillance video, previously shared by the Department of the Interior with Fox News, of someone vandalizing the pool. The June 19 video, taken in the middle of the afternoon after news had broken of the damage to the pool, appears to show a person reaching into the water and pulling something out. However, it is unclear whether this individual was engaged in vandalism.

The White House has not provided evidence of people causing long gashes or a series of gashes. The press release also included links to images of damage to the pool, including a jagged line on the bottom of the pool posted by a TMZ DC reporter on X, but it was unclear what had caused it. Nor has the administration provided evidence someone illicitly dumped something in the pool to cause algae growth.

The White House press release linked to a court filing from Frank Lands, the deputy director of operations for the National Park Service, stating that police on June 9 responded to an “NPS report of damage to the reflecting pool, including a caulk over the foam sealant that was cut with a sharp knife or razor and destruction of delaminating surface material.” Lands also said that “approximately 70 fence post tops were thrown into the pool.” It is unclear who is alleged to have made these cuts or thrown the fence post tops.

The Department of the Interior sent us a link to one of its X posts, which said, “Six individuals have been arrested for vandalism at the Reflecting Pool.” The post added that seven others were given federal citations and that 17 police reports for vandalism had been filed.

The department would not give us further information about these arrests and citations, including any details of the individuals’ alleged infractions. Not did they provide the names of the alleged vandals. The White House press release said that there had been at least seven arrests, seven federal citations and 18 police reports filed but again did not provide more details, other than to link to multiple news stories mentioning an Olympic canoeist who has disputed that he vandalized the pool. Washington, D.C.’s Metropolitan Police Department referred us to the NPS.

Brady McCarron, a spokesperson for the U.S. Marshals Service, told us that as of the morning of June 24, “we are showing 5 arrests” listed as being by the DC Safe Task Force, including one on June 19 for “vandalism (attempted destruction of property/defacing public property)” and four on June 20 for “Destruction of government property.” He did not provide further details on these arrests. The DC Safe Task Force is a multiagency federal body created by Trump “to surge law enforcement presence in public spaces, strictly enforce ‘quality-of-life’ laws, and maximize federal immigration enforcement within the District.”

Meanwhile, experts in pools, waterproof coatings and algae have said that there are many possible causes for the reflecting pool’s issues that have nothing to do with vandalism. Below, we will discuss competing explanations.

Peeling problems

Despite Trump’s claims of vandalism to the more than 100-year-old reflecting pool, it’s not clear what caused damage to its new lining. When pressed on June 22 on whether he had proof that vandals had made cuts in the pool, the president seemed to suggest the cuts themselves were the proof.

“Well, let’s put it this way. When you have a 350 — I think it’s 350, not 250 — a 350-foot slit from one end to the other, you think that’s proof? You think that’s proof?” Trump said to a reporter. He later suggested that there was photographic evidence, but when a reporter asked the president to release those photos Trump said, “You’ll see it in court.” He also suggested contacting the Interior and Parks departments.

What is known is that the Department of the Interior awarded a no-bid contract on April 3 to Atlantic Industrial Coatings to paint the reflecting pool, with supplemental agreements issued through June 15 to total $14.7 million. The agency justified not getting bids from various contractors by saying the project was urgent and needed to be completed by July 4.

The plan was to install an epoxy primer on top of the pool’s concrete slabs, followed by a polyurea lining tinted “American flag blue,” Superintendent of National Mall and Memorial Parks Kevin Griess explained in May 18 court filings.

“The rehabilitation incorporated a combination of repair materials, epoxy priming technology, elastomeric waterproofing systems, and protective finish coatings,” a June 18 press release from Rhino Linings, the company whose products were used for the new liner, said.

The idea of installing the lining over the full bottom of the pool was first suggested by the Trump administration, Griess said, and not initially by his staff. The original focus was on replacing the failed expansion joints, a major source of leakage. The project did not address the pool’s leaking pipes.

On June 18, around two weeks after the pool was refilled following the renovation, news outlets began reporting that blue material was peeling off the pool’s bottom. The New York Times later reported on June 23 that workers had identified the peeling at least two days earlier, while also noting separate damage to foam in the pool’s expansion joints as of June 9. These joints — which go around the perimeter of the pool and horizontally across it in several places — allow the pool’s concrete slabs to expand and contract as the weather changes.

However, experts in pools and waterproof coatings have said that there are many possible reasons that a coating can improperly adhere.

“You have to account for ambient conditions like rain, sun, humidity, moisture control in your substrate, thickness, evenness, and chemical compatibility,” Steve Goodale, a swimming pool consultant, told Wired, speaking about the difficulty of applying a waterproof pool lining. “There are so many things that can go wrong with that process. If the material hasn’t bonded to the substrate for any number of reasons, then ultimately, the entire system will fail.”

Goodale told the Washington Post that improper surface preparation or water seeping into the lining from the pool or from under it could also contribute to the peeling. He also said that the hydrogen peroxide that the Interior Department had used to try to treat the algae in the pool could have had an impact on the coating, although he said that this would be more likely to lead to “fading, hazing or breakdown of the material” than peeling. News outlets reported that the department had said it was using hydrogen peroxide to treat the algae starting as early as June 16.

David McFayden, CEO of the paint and inspections services company KTA-Tator, told Scientific American that the available information was too limited to blame any one factor for the peeling, but he said issues worth investigating include how the surface was prepared before applying the coating and the water chemistry.

Atlantic Industrial Coatings, the contractor for the project, said in a June 21 statement that it and the NPS had “identified some areas in the Reflecting Pool that require repairs,” which will be done under warranty, and that these “do not indicate a failure of the liner.” The following day, Rhino Linings, the company that made the pool’s liner, said in a statement that the issues constituted “localized areas of finish coat separation,” and not an issue with the “underlying waterproofing membrane.”

“Was it manual intervention that made those few places peel, or was that the chemical composition of what was in the water?” Rhino vice president Francois Rivard told Politico. “We don’t know until we have further results at this point, but it is not problematic,” he said, explaining that the peeling only appears to affect the outer blue layer that is for aesthetic purposes.

Unclear timeline of damage

Concerns about the pool’s new coating predate the most recently identified peeling issues.

Tim Auerhahn, chairman of the pool training and consulting company the Aquatic Council, told the New York Times for a May 8 story that he would want to look closely at the impact of Trump driving his motorcade over the newly coated surface of the pool the day before. The Times reported May 12 that Department of Interior staff had expressed concerns about bubbling and small holes in a layer of the waterproofing material. And the Times report from June 23 and court document linked to in the White House press release indicated that Park Police were aware of damage to or near the pool’s foam expansion joints by June 9.

This timeline indicates the new material in the pool had problems before the June 19 and 20 arrests the U.S. Marshals spokesperson mentioned, and before the June 19 surveillance video of someone removing something from the pool the White House press release linked to.

Few details are available about the arrests. An Olympic canoeist, David Carter Hearn, told news outlets that he was arrested on June 19 for alleged destruction of government property. He said a piece of the blue lining had already partly peeled off and he touched it out of curiosity. He said he did not destroy anything.

There are some images and videos from reporters that indicate people on June 19 — once the peeling pool was already a major news event — broke off already-peeling coating or held pieces in their hands. However, there isn’t evidence of people making gashes with a knife.

The Washington Post also reported on June 20 seeing a U.S. Marshal detain someone for allegedly taking paint out of the pool and on June 21 seeing a Park Police officer issue someone a citation for allegedly removing something from the water.

A surge in algae 

Beyond stopping leaking, Trump’s reflecting pool project aimed to reduce algae, which has been a recurring issue for the reflecting pool.

The project included $1.7 million in funding to Greenwater Services to install a new system for algae control. Nanobubble systems for algae control, such as the one installed by Greenwater Services, work by introducing tiny ozone bubbles to a body of water, which can kill algae.

But despite efforts to mitigate the algae, an analysis done for the Washington Post indicated that the level of algae on June 13 — the week after the pool was refilled — was higher than in other June images going back to 2021.

Trump claimed that someone may have added fertilizer to the water to cause the algal growth, but he didn’t provide any evidence for this claim.

Chapra, the water quality modeler from Tufts, told us that the reflecting pool represents “the recipe for growing algae,” without needing to invoke vandalism.

The pool is “shallow, there’s no flushing, they don’t run water through it on a permanent basis,” he said. “There’s no mixing, because they want to keep it nice and flat, so you get a reflection.” Furthermore, he said, “there’s no shading anywhere to keep solar radiation out, and somebody decided to paint the bottom dark blue,” even though this makes the pool retain more heat. The pool probably also uses high-nutrient water, he added.

The president has blamed the pool’s past algae problems on a change to the pool’s water source made under former President Barack Obama. In 2012, the government switched from filling the pool with municipal DC water to ozone-treated water from the Tidal Basin, which is fed by the Potomac River.

“He took the water from the river,” Trump said of Obama on June 22. “It turned out to be putrid and it destroyed the whole thing. Spent over $100 million.”

That total is incorrect. As we previously wrote, the Obama-era restoration, which also reinforced the pool’s sinking foundation and replaced its concrete bottom, cost around $35 million.

When the reflecting pool was refilled in early June, a spokesperson for the Department of the Interior told us, it had been filled with “DC Water,” or municipal water. Even after the Obama-era renovations, the pool had periodically been filled with city drinking water when there was substantial algae in the Tidal Basin.

Chapra said that feeding the pool from the Tidal Basin would be the “worst” in terms of algae, given that the Potomac River has “plenty of nutrients” and algae.

However, using DC Water does not eliminate the potential for algae. Ashley Bair, a researcher at the water treatment company Usalco, told Vox that a type of phosphorus added to municipal water to form a coating on the inside of lead pipes could feed algae if the water were not treated properly. DC Water has added orthophosphate since 2004, according to its website, after a switch in disinfectant and a change in water chemistry caused lead to be released into the water from pipes.

Chapra also said that regardless of water source, feces from animals and fine particulates with phosphorus in the air can add to the nutrients in an open pool. He added that he was skeptical of the ozone nanobubble technology for the project. “High enough concentrations of ozone will break the cell walls of the algae, but that releases the nutrients back into the water, and it’s not going to kill all of them,” he said. Ozone also breaks down in sunlight, he added.

Given all these factors, he said, vandalism simply “wasn’t the first thing that popped into my mind” upon seeing the algal growth in the pool.

“Like I said at the beginning, shallow, no flushing, no mixing, high-nutrient water, no shading, dark blue bottom, go figure,” he said.