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Potential Solutions for the Algae Problem
From The Reflecting Pool fiasco — Jun 25, 2026
The Reflecting Pool fiasco — Jun 25, 2026 — starts at 0:00
Sean Romis for him Out here on the National Mall about halfway between the World War I and Lincoln Memorials, which is to say, I'm standing next to our reflecting pool. And I'd like to take a moment just sit right there, talk about how It isn't just nominally a reflecting pool. I've lived here for about a decade and Just about anyt timee you come out here, you'll see people in a state of quiet contemplation. I think that's because You know, it's a quiet place. It's it's open. its it's free. It's it's free for you in the winter to try and Test your luck skating the reflecting pool in your sneakers or in the summer, I've seen people takeake a little dip in, sometimes intentionally, sometimes unintentionally As you know, as of late, it's felt a lot less free out here the reflecting pool and We're gonna get into it on todayoday Explain from Box Support for this show today comes from Anthropic, the team behind Claud. Claud is the AI for minds that don't stop at good enough. It's the collaborator that actually understands your entire workflow and thinks with you Whether you're debugging code at midnight or strategizing your next business move, Claude extends your thinking to tackle the problems that matter. With deep research Claud's research capabilities go way deeper than basic web search, comprehensive reliable analysis with proper citations Turning hours of research into minutes for problems worth solving, you can get started with claud at claud. a slash today exxplain. That's claud. ai slash today explained Support for this show comes from Fetch Pet Insurance. Do you have a pet Every six seconds, a pet owner in the US gets hit with a vet bill of over a thousand dollars. and it's almost always an unwelcome surprise That's where Fetch pet insurance comes in. Fetch is the most complete pet insurance get paid back up to ninety percent of vet bills You can use any vet in the US and Canada. All vets are in network Go to fetchpet dot com slash save right now for your free quote. That's fetchpet dot com slash save Green and it'll do Today explained I'm Christina Kotaruucci, I'm a senior writer at Slate. What is it about the Reflecting Pool that has captured not only I think national, but international attention That stretch of federal land between the Washington Monument and the Lincoln Memorial is maybe, you know the most iconic American property that we have. It's between two monuments representing two of our greatest and beloved presidents. You know, it's the site of MLK I have a dream Sech. It's the thing that you have to go to whenever you visit DC, whether that's on an eighth grade field trip or you know, I met some people down there who were there for work conferences. It's sort of the place where tourists gather more than any other. It's like where Fororerest Gump and Jenny are reunited And where Spider Man goes on his field trip. No My friends are up there. What?on't worry ma'am, everything's gonna to be okay. Yes, more to the point. off all of Trump's you know, DC renovations, besides maybe the part of the White House that he tore down, it's the most recognizable thing to people who don't live in DC. Well, let's talk about how this all got started. Was there a problem that needed to be addressed to begin with Yes and no So when I first heard that Trump was painting the reflecting pool blue, you know, and this is like a bright blue, like I want to say the color of Sonic the Hedgehob. He said American flag Hello And so you can't do better than that. Although, you know, having been down there, I would say it's a little more turquoise, but that's beside the point The fact is the reflecting pool has been plagued by leaks and algae for decades, you know, maybe even since its construction. And so Trump is not the first president to try to fix that. And Barack Obama you know spent thirty five million dollars installing a new water filtration and treatment facility A new steel reinforced foundation, a new filtration system that pumps water from the potomac tidal basin. And pretty much on time, pretty much on budget, the new pool opened. But less than a month later, the famous pool of water is full of algae. The algae blooms are endemic to this large pool of stagnant water sitting in the DC sun The smell was terrible. L smells like wet dog down here, you know? Wastte from the geese P us all do Tvelles and everything else that came over him, plus the alge There's also the fact that it's created with slabs of concrete that you expand and contract with shifting temperatures, maybe freeze in the wintertime, you under the water. It leaks millions of gallons of water a year. And so yes, there are things about the reflecting pool that should be repaired and that previous presidents have tried and failed to repair, but was the color of it one of them? No It'sot that easy any Okay, so is like fifty, fifty on solid footing here to go in and fix the reflecting pool I guess a project like this starts with who's going to do the work. And there is some controversy there, right? Oh, absolutely. So normally the federal government would seek offers from multiple different contractors to see who could do the work most efficiently, cost effectively, and best Instead, Trump handpicked two different vendors to award contracts to. I said my poool guy, I said, takeake a look at it. And he said, Well Sir We can do it. One was for over fourteen million dollars, the other one for more than a million. These were no bid contracts, which means that there were no other contractors submitting plans for how they would do the job. Every time I do a development, I do swimming pools. I know more about swimming pools. I said, why can't we put The wonderful material, which is thick, pasty, beautiful like rubber But industrial strength, why can't we use it And let's pick the color blue from the American flag, which is what we did. One of the contractors was based in Virginia. Trump said someone who had done work on his Virginia golf course and done some pools there. And this was for the waterproofing, you know, blue sealant on the bottom of the pool. President Trump originally promised that his hand picked no bid contractor would just charge one point eight million dollars for this repair and paint job But federal records show the interior Department is now planning to pay that contractor, Atlantic Industrial Coatings more than seven times that. The other one was a company in Ohio called Get this Greenwater Services. Greenwater Services received a one million plus dollar no bid contract to help install the water filtration systems inside The Lincoln Memorial Reflecting Pool. The owner of which was a major Trump donor and who Trump had actually called out from the stage of a big event for being such a big supporter. JJ Cfarro from Florida and from Cleveland. He's a man who made a lot of money in Cleveland, does a good job and a fantastic man fifty thousand dollars. JJ, thank you who owns a property next to Mar a Lago. And who are we kidding looks like a cartoon villain? Oh my God, absolutely. He's like he has a perfect little mustache, you know, a double breasted herringbone jacket in every photo that news reports are using, which I'm honestly kind of jealous of. I mean, why does this guy look like if Hitler decided he was going to be a used car salesman Why does he look like the penguin from Batman? I mean, this guy looks like the CEO villain in an eighties movie who's coming into a town in order to knock down a children's playground. It's like Donny Brasco got stung by a bee But all of which is to say this was not done on the up and up in the way that the federal government typically engages in these projects. Where do the problems begin once they break ground So it started when they finished, you know the sealant on the bottom and paning it blue and they refilled it with water and almost immediately, like within a week It was home to the largest algae bloom in at least five years, according to a Washington Post analysis. We were trying to look at the new American flag blue and we can't see that. She is doing good J. So what do you think about the reflecting fool behind you? How does it look? Not good No it's not good. I mean it look it looks green It was hilarious to see Trump calling this thing American flag Blue because it was actually bright green. Everybody's looking at that reflecting pool, they can't believe it. reflects. We used it dark blue It's called American Flag Blue. want People who opposed President Trump really jumped on that failure because it was something you could really see with your own two eyes. It actually reminded me of the debate over his inauguration crowds where you know, he was like, there were more people than have ever been on the National Mall. This was the largest audience to ever witness an inauguration pereriod. And then there were actually pictures from above where you were like, no, the National Mall was not even half full. Sean Spicer, our press secretary Gave. Alternative facts. Then. That precious blue paint that Trump had spent, you know, nearly fifteen million dollars of taxpayer money resealing started peeling up from the edges. This is just a loose flap of what appears to be that sealant downown here in the water, just flapping like that. There have been tourists coming along tearing off pieces to take his souvenirs. Check this out. That American flag blue color that the president picked out is now peeling off with chunks of paint floating in the water. And then people show up to gawk at that. and then all of a sudden we're having people being arrested on the national Mall Yeah, this is this is where it really turns. you know, it would be farcical if people weren't actually being criminalized for this. but You know, people were reaching into this putrid water, picking pieces of the pool's lining out of the water, then were arrested by park police for vandalizing federal property And obviously the president is now saying Vandals were cutting up The lining of the reflecting pool. Probably a box cutter or a knife of some kind. Is there any evidence of that No, I mean This has really taken the shape of just about every controversy around President Trump's failures, where his supporters immediately jump to conspiracy theorory Somebody said they might have put fertilizer. They did something to create the alga. So people were saying that some bureaucrats had put fertilizer in the pool to make the algae bloom. They went in there with a knife President Trump was saying,ah that someone had come in with a box cutter and cut a three hundred and fifty foot gash down the reflecting pool I mean, look, I saw this thing peeling up like skin peeling off of a sunburn. It's an absolutely absurd claim. Do we know what actually caused the peeling, if not a guy with box cutters be the hydrogen peroxide that workers poured into the pool to try to kill the algae could be part of it. It could be know that the surface was improperly prepared before the sealant was sprayed onto it. It could have also been that water is coming up beneath it because one of the things that does need to be repaired at the reflecting pool is all of these leaky seams between the slabs of concrete. By the way, after the administration supposedly fixed those leaks, Trump's motorcade drove across it which might have put too much weight on it and damaged the newly repaired seals between the seams. But what I can tell you is that, you know, it wasn't coming off in small flakes like paint chips. It was peeling off in sheets because it's almost like a plasticy coating It feels like they should have known that They needed to do a good job here. It just feels like there were going to be a lot of eyes on this project and like they didn't do a very good job. Why the heck not I mean, I can only speculate, but what I know of the Trump administration and of President Trump's demeanor is that they're not motivated by taking slow and deliberative steps toward doing a good job. They're motivated by easy wins, by big flashy aesthetic moments, and by an extreme almost delusional confidence that President Trump alone can fix things by extreme deference to him. So if Trump said, I want this guy to paint my reflecting pool and I want it done in two weeks Anyone actually responsible for getting that done is like, sir, yes, sir. know, they're not going to be like, well, you know, actually we should take a few months to seek out competing bids and have the nation's best engineers do research on how we can repair this in an enduring way I think you probably also didn't care if it If it failed again in a couple of weeks, as long as it lasted through his big rally and through july fourth, you know he's not one who cares about what comes after him. This is his property. He doesn't think of it as a public space that he needs to steward with an enduring competence You can read Christina at slate. com When we're back on today exxplained, our buddy Benji is gonna tell us how Relecting pool algae became Trump's biggest problem with a body of water since the Strait of Hormuz Su for todayod Explained comes from Framer. If your team wants a website that looks and feels hand crafted but is still fast to ship, Framer is built for that You design on a visual canvas with responsive layouts hosting and a CMS built in, so the work is production ready from day one. Agents work alongside you to draft pages and polish sections, then you review and publish what goes live. Kramer is the pro site buildilder for creators, teams and businesses that want a professional site and care enough to get every detail right. Agents solve the gap between AI generated ideas and production, ready, website work aggent works in the same place where the real site is designed, managed, reviewed, and published. It stays on the canvas, stays editable, and can be published when the team is ready. Agents and Framer work alongside teams to streamline collaboration on the same canvas, build custom code components, create and manage CMS content, optimize SEO settings, and ship everything all in one place B now you can get more out of your site from a framer specialist or get started building for free today at frramer. com slash explained for thirty percent off a framer pro annual plan. That's framer. com slash explain for thirty percent off framer d. com slash explained. Rules and restrictions may apply. The boort for to explain comes from AG one between summer travel and spontaneous plans. It's normal. 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You can go to drinkagG one dot com slash explain to get a free morning person hat and free AG onene flavor sampler in your welcome kit with your first AG one subscription, which is an eighty two dollarars value. that's drink agG one dot com slash explain The port shate com from Anthropic in case you were wondering who's behind Claude? That's Anthropic. Claude is the AI for minds that don't stop it good enough. Is that you? It's the collaborator that actually understands your entire workflow and thinks with you. Have you been looking for that? Whether you're debugging code at midnight or strategizing your next business move, Claude extends your thinking to tackle the problems that matter with deep research Claud's research capabilities go way deeper than basic web search, comprehensive releliable analysis with proper citations Turning hours of research into minutes. We love a proper citation, don't we? Plus, you can connect cllaud to your professional tools like GitHub Jira Hub Spot Notion, Google Worspace and watch it become your command center with context from all your work. That means Claude has contexts from your calendar emails All of your go to tools. For problems worth solving, get started with claw cllaud. ai slash today exxplained. That's claud d. Ai slash today exxplained When green is all there is to be could make you Wonder why Today Explain is back. Christina's gone, but we now got Benji Jones here. He's a senior correspondent at Vox who writes about the environment and biodiversity. and this week Algae. And you called up a bunch of scientists to better understand the algae situation, whereere the scientists eager to talk about algae Yeah it wass kind of amazing. Usually it is difficult to get a hold of people really quickly, but in this case, basically everyone I reached out to all these limnologists or phytocologists, people who study lakes and algae, werere super eager to talk. I think this is like They're having a moment right now. This is their Super Bowl. It is. How did they help you understand the situation in our nations's Foremost reflecting pool. Well, they told me a lot about algae, probably more than I've ever known So what is algae? Algae is not a plant, but it does photosynthesize and so it needs a lot of sunlight It also likes a lot of warmth and stagnant water. And so when you think about that, and then you look at the reflecting pool, which is this large has a large surface area. It's super shallow by design meant to not be very turbulent, it is like literally a heaven for algae. So you couldn't design a better place for algae, essentially And that in particular, is not Donald Trump's fault because he did not invent the reflecting pool. No, and it's been plagued by algae blooms in the past. I mean, also, just to be clear, algae blooms are not an unusual phenomenon. Algae is everywhere. The kind of algae that was in the reflecting pool is a very common kind of green algae. so like it is not surprising to see algae in a water body. What was surprising is that in contrast to this kind of mission by President Trump, his administration to get this pool crystal clear with a blue bottom before july fourth. You have something you' going to be very proud of and it'll last for fifty to one hundred years before you have to do anything with it. Right after they refilled this pool with clean water, it just ballooned with algae and turned this like pea soup green. And not even a week later, it's already completely green. It's Mexican flag green. The first thing we noticed was that it was green. Would you want tona swim in that water No It has cleared up substantially since that initial bloom, which was about a week ago now But then the question is like, all right, so The reflecting pool is prone to algae, but why did that bloom happen just after it was refilled just after this renovation? And so algae doesn't just need sunlight and warmth, both of which are very common in the summer, it also needs nutrients. So nutrients are incredibly important when you think about what causes an algaal bloom And by nutrients, I really mean nitrogen and phosphorus. So those are the same elements that we use to fertilize our crops. Those are what feed algae Then the question is, okay, where did those nutrients come from And This is an interesting part of the story to me because in the past, the reflecting pool has been filled either with water from the tidal basin, which is this man madeade reservoir that's connected to the potomac. The potomac is not known for being super clean, so it does have nutrient pollution in it But the reflecting pool can also be filled with DC water. so water from the city system, which is essentially what ends up in our taps in DC. And in this case, they filled the reflecting pool with DC water according to the Department of the Interior, which manages the Park Service, which manages this pool And then my question was, okay, where are the nutrients for this algae coming from if they're filling the pool with DC water And what scientists told me is that DC actually adds a form of phosphorus to its water supply because when you add phosphorus It can prevent the leaching of heavy metals from pipes into the water supply. So it essentially creates like a coating on the interior of pipes. And so the city purposefully adds some phosphorus to its water and that phosphorus can act as a nutrient for the algae. So even if you're literally like turning on a tap and filling the pool with clean water, there is already some food for algae to grow Because they filled this pool all at once, there was nutrients available, there was sunlight, there was warmth, and they painted the bottom of the pool this darker color, so that might absorb some more light, some more warmth, That is what scientists say created this sort of sudden bloom of algae government officials. tried to solve this problem in a couple of different ways. One way was dumping bottles of hydrogen peroxide in it, which maybe sounds worse than it is. That's actually like a fairly common way to clean up a water body with algae and it's not toxic And then they also used this technology called like nanobubble technology And because the pool has become a lot clear, it's possible that some of that has worked The challenge when you're killing off Any kind of algae in the beginning of trying to treat a bloom is that it's going to kill a bunch of those organisms. When those organisms die, their nutrients in their bodies gets released into the water, which then creates a supply of food for the algae that is still living there. And so it can sort of create another bloom cycle when you have a die off of some of the algae. So if you don't hit everything at once with a pretty high dose of chemicals It's very easy to see these recurring blooms And beyond that, the one issue that scientists told me in terms of how do you actually to a place where you have an algae free pool you need to deal with the nutrients and it doesn't seem like there has been really a solution there so far. L the administration doesn't seem to have treated the water going into the pool for nutrients, like taking out the phosphorus and the nitrogen And then there needs to be ongoing nutrient removal if you don't want to see a bloom return Did you ask any of your scientists about that? Like what could the Trump administration be doing right now to actually win this war they're waging against algae? Yeah. I mean, I would not want to go aad to head with algae because this stuff is like, it's impressive, honestly. Algae is like it's been around for billions of years. It's like one of the early organisms on our planet. It knows how to survive and it grows so quickly. but like These algae they're microscopic algae and they're unicellular. It's literally a single cell and they can divide like several times in a single day. And if you have hundreds or thousands of cells that just like exponentially can grow. So that's why you can see a bloom so quickly. But I will say the person who was like, yeah, I could get it done, Ashley Bear. She works for a water treatment company. This is very much in our wheelhouse. and I kind of trust her. I think she could get it done She was like, look, This is not that different than any swimming pool. Yes, it's like more surface area to water depth ratio, whatever. But if you wanted to take like a pretty robust chemical approach, you could do that. L you could blast the whole thing with chlorine and it would be clear I think the downside of that is that chlorine smells bad And it kills everything. And unless you're continuously monitoring, it's not that treatment is not gonna to last. but one approach is just to sort of blast it with chemicals in a way that the Trump administration has not done. So that's one option, is like more of a chemical approach and then you'd wanna monitor it over time. But then I talked to one researcher, Alan Wilson at Auburn University in Alabama and he's like she's Algae expert, he works in fish ponds, which often have algae problems because you're putting a bunch of food in them for the catfish And this guy was basically like, look
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