Bloom Baby Bloom: Why U.S. Waters Are Turning Green

The Reflecting Pool In DC Mirrors A Larger Algae Crisis Across The Country.

Photo by Wouter van Dijke on Unsplash

The Lincoln Memorial Reflecting Pool was supposed to be ready for its close-up.

It was freshly renovated at a cost of more than $14 million, according to federal contract records. The basin painted a proud “American Flag Blue” was ready for the nation’s 250th birthday bash. The pool was set to gleam beneath the July 4th fireworks like a patriotic mirror to the sky.

Then, it turned green.

Photos showed National Park Service workers wading in to battle an algae bloom that took over the historic landmark.

According to reports, workers started pouring hydrogen peroxide into the water as part of algae-control efforts, a treatment that, if the concentration is wrong, can cause skin, eye, and respiratory irritation to anyone who wanders too close.

Sounds like the cities that spend millions renovating a water treatment plant, only to use cheap fixes (ahem, chloramines) months later to deal with ongoing issues. Many leaders don’t get to the root of the problem when it comes to water issues. You have to know what’s in the water, so you can treat it more effectively instead of creating a chemical cocktail mix.

But this story isn’t about a botched renovation.

Mother Nature Doesn’t Care About Your Renovation Budget

The Department of the Interior announced that “nanobubbler technology has successfully destroyed the algae bloom.” But environmental scientists are less celebratory.

“The Fourth of July is probably the worst time of year because that’s when the temperature is highest,” Hans Paerl, a research professor of Marine and Environmental Sciences at UNC Chapel Hill, told USA TODAY. “It’s Mother Nature that’s really running the show.”

The math here is pretty unforgiving. Algae thrive in warm, stagnant water loaded with nutrients like nitrogen and phosphorus.

Washington in July is famously swampy, surrounded by the Chesapeake Bay watershed and the Potomac River, and NOAA is forecasting another above-normal-temp summer.

The Reflecting Pool isn’t special. Algae are everywhere this summer.

Harmful algal blooms, or HABs, are rapid overgrowths of cyanobacteria, commonly called blue-green algae, in lakes, ponds, rivers, and reservoirs.

Editor’s note: Review your HAB FAQs and these Healthy Water Habits to help protect yourself.

HABs love exactly what summer 2026 is serving: warm water, abundant sunlight, and nutrients washing in from agricultural runoff, lawn fertilizers, and septic systems.

The earliest ever harmful algae bloom was confirmed in April at Cayuga Lake in New York due to heavy rainfall and nutrient runoff. It’s the earliest bloom on record since 2018, when the Community Science Institute (CSI) began its HAB Monitoring Program.

In Oregon, the monitoring season began in May, and you can track advisories here.

Record heat is accelerating the problem, warming surface waters faster and creating conditions that researchers say are driving increases in HAB frequency, duration, and geographic range.

The Reflecting Pool’s algae is an aesthetic headache, but in swimming lakes across the country, the stakes are considerably higher. First, the economic impacts of HABs to fisheries and recreational areas can be extensive. And of course, they also impact our health and the health of our ecosystems.

Cyanobacteria produce toxins, cyanotoxins, that can cause liver damage, neurological injury, and in the worst cases, death. Dogs are especially vulnerable; they drink directly from water bodies, ingest large amounts relative to their body weight, and can die within hours of exposure to certain toxins.

Anatoxins, which target the nervous system, can kill a dog within minutes to hours.

These cases happen every summer at lakes and swimming holes where families have visited for years without incident, because HABs can develop within 24 to 48 hours when conditions are right.

Children are also vulnerable. They can swallow water when swimming. They stay in the water longer. Their developing organ systems are more susceptible to toxin-induced damage. Skin contact alone can cause rashes and blistering. Inhaling aerosols from HAB-affected water, the kind you get jet skiing or waterskiing, can trigger respiratory irritation and asthma attacks.

The water doesn’t have to look dangerous. Some blooms are invisible. Others develop within 24 to 48 hours. A lake that was fine last weekend may not be fine this weekend.

Look before you leap!

The rule is simple: if in doubt, stay out.

Do not swim in, wade through, or let your pets drink from water that appears green, blue-green, or pea-soup colored, or has surface scums, foam along the shoreline, or an unusual odor. That rule applies to familiar places you’ve visited for years. HAB conditions can develop overnight.

Before visiting any lake or swimming area, check your state health department’s website. Most states with active HAB monitoring programs post current advisories by water body. Look before you go. You can find more resources here.

If your dog swims in or drinks from water you’re even slightly uncertain about, rinse them immediately with clean water and watch for drooling, staggering, convulsions, difficulty breathing, or sudden weakness. Any of those signs means an emergency vet visit. There is no antidote. Supportive care must begin immediately.

If you or your child develops skin rashes, eye irritation, nausea, vomiting, or muscle weakness after swimming, seek medical care and tell your doctor about the potential bloom exposure.

The Pool is a Mirror

The Lincoln Memorial Reflecting Pool was built to reflect something. Right now, it’s reflecting a truth we’ve been slow to reckon with. U.S. waters are under stress, and cosmetic fixes don’t address the underlying conditions driving that strain.

Nutrient pollution. Rising temperatures. Aging water infrastructure. Budget cuts. These forces are turning water green from the National Mall to the swimming holes where families have gathered for generations.

The pool is just a very large, very public illustration of a problem that’s been building for decades. Toxic algae blooms have increased 30-fold since the 1960s with more than 300 coastal systems impacted and nearly every state in the U.S. experiencing HABs, according to the National Centers for Coastal Ocean Science (NCCOS).

So, the emergency response? The expensive equipment? The confident statements about problems being solved? It’s all been played out. Next comes the quiet acknowledgment, months later, that nothing fundamental changed.

Keep your eyes on the water.

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Have you encountered a harmful algal bloom yet this summer? Leave a comment below with your location and what you saw.