Just days after the Trump administration completed millions of dollars in renovations on the Lincoln Memorial Reflecting Pool to make it American flag-blue, residents and online users noted it had turned a phosphorescent green.
Here’s why:
The calm, still waters of the Reflecting Pool make it an ideal nursery for algae growth. Algae need nitrogen and phosphorus to grow, and the Reflecting Pool is primarily fed by the Potomac River, which gets heavy doses of those nutrients from nearby urban and agricultural lands.
The Potomac also absorbed one of the largest sewage spills in U.S. history earlier this year when a pipe burst five miles upstream of Washington, although that event probably happened too long ago to contribute to the algal bloom today.
Untreated sewage is high in nitrogen and phosphorus. When nutrient levels are high, feasting algae can quickly reproduce.
The Department of the Interior said when the algae first appeared that it was “residual,” from the supply lines to the pool.
Experts also speculate that the darker blue color may be helping the Reflecting Pool absorb more heat. The higher temperatures promote algae growth by allowing their metabolisms to shift into overdrive.
Summer temperatures in D.C. aren’t helping. This week, temperatures are as high as 95 degrees in the city, prompting a heat alert.
The combination probably explains the excessive growth, turning the water surface an opaque green and preventing onlookers from seeing the new blue hue of the concrete basin.
Algae are important and beneficial organisms when the ecosystem is in balance. They’re the base of the aquatic food chain, fed on by herbivores of all shapes and sizes, including shrimp and juvenile fish, which in turn feed organisms higher up the food chain. The single-celled organisms use the power of the sun to produce energy through photosynthesis, similar to houseplants on your balcony.
In an effort combat the algae in the Reflecting Pool, employees of the National Park Service were seen pouring in gallons of hydrogen peroxide, a chemical commonly used in pool maintenance.
The Department of the Interior also is employing a “high-tech nanobubble ozone technology” to destroy the cells of the algae.
Ozone — yes, the same irritant that is in smog — is a gas composed of three oxygen molecules, and the small size of the bubbles allow the most gas transfer into the water, where it can damage algal cells, similar to how it irritates our lungs.
This only treats the symptoms, however. Generally, ozone nanobubbling is effective as a temporary solution for algae blooms. Longer-term fixes would have to address what makes the Reflecting Pool so ideal for algae, such as its depth, darker color and inflow of nitrogen and phosphorus.

Many Americans will have the day off on Friday, June 19, to celebrate Juneteenth, the federal holiday commemorating the end of slavery. While most stores will remain open, some services will be unavailable.
The stock market and most banks will be closed on Friday. While many stores will remain open, make sure to check local store hours as they may vary by location.
Also known as Freedom Day or Emancipation Day, Juneteenth marks the day in 1865 when Union soldiers arrived in Galveston, Texas, to inform enslaved people that the Civil War had ended and they were free.
Read on to see what’s open on Juneteenth.
Is Walmart open?
Yes, Walmart will operate during normal hours on Juneteenth, a spokesperson confirmed.
Is Costco open?
While Costco is closed for other federal holidays, it will remain open for Juneteenth.
Is Target open?
Target will be open during normal business hours, which vary depending on location, according to a spokesperson.
What grocery stores are open?
Food Lion
Kroger
Stop & Shop
Trader Joe’s
Wegmans
Whole Foods
What stores and fast-food chains are open?
Apple
CVS
Dunkin’
HomeGoods
Homesense
IHOP
Kohl’s
Lowe’s
Macy’s (some stores will have extended hours)
Marshalls
McDonald’s
Petco
Nordstrom
Sierra
Starbucks
Taco Bell
TJ Maxx
Are banks open?
Major banks such as Bank of America, Chase and Wells Fargo will be closed on Friday.
Is the stock market open?
The stock market will be closed on June 19 in observance of the Juneteenth holiday, according to the New York Stock Exchange and Nasdaq websites.
Are FedEx, UPS and USPS open on Juneteenth?
FedEx and UPS will make deliveries and keep retail locations open on June 19, according to their respective websites.
However, you may run into issues if you’re trying to mail something. All U.S. Postal Service locations will be closed, and USPS mail deliveries will be suspended for Juneteenth. Services will resume Saturday, June 20, according to USPS.

Many Americans will have the day off on Friday, June 19, to celebrate Juneteenth, the federal holiday commemorating the end of slavery. While most stores will remain open, some services will be unavailable.
The stock market and most banks will be closed on Friday. While many stores will remain open, make sure to check local store hours as they may vary by location.
Also known as Freedom Day or Emancipation Day, Juneteenth marks the day in 1865 when Union soldiers arrived in Galveston, Texas, to inform enslaved people that the Civil War had ended and they were free.
Read on to see what’s open on Juneteenth.
Is Walmart open?
Yes, Walmart will operate during normal hours on Juneteenth, a spokesperson confirmed.
Is Costco open?
While Costco is closed for other federal holidays, it will remain open for Juneteenth.
Is Target open?
Target will be open during normal business hours, which vary depending on location, according to a spokesperson.
What grocery stores are open?Food LionKrogerStop & ShopTrader Joe’sWegmansWhole FoodsWhat stores and fast-food chains are open?AppleCVSDunkin’HomeGoodsHomesenseIHOPKohl’sLowe’sMacy’s (some stores will have extended hours)MarshallsMcDonald’sPetcoNordstromSierraStarbucks Taco BellTJ MaxxAre banks open?
Major banks such as Bank of America, Chase and Wells Fargo will be closed on Friday.
Is the stock market open?
The stock market will be closed on June 19 in observance of the Juneteenth holiday, according to the New York Stock Exchange and Nasdaq websites.
Are FedEx, UPS and USPS open on Juneteenth?
FedEx and UPS will make deliveries and keep retail locations open on June 19, according to their respective websites.
However, you may run into issues if you’re trying to mail something. All U.S. Postal Service locations will be closed, and USPS mail deliveries will be suspended for Juneteenth. Services will resume Saturday, June 20, according to USPS.

Early signs that the Strait of Hormuz is reopening have eased the most acute threat to global energy supplies, but economic damages from the nearly four months of war will take months to unwind, analysts warned.
The U.S. and Iran signed a memorandum Thursday to open the Strait of Hormuz, ending a war that has upended global energy supply chains, pushed inflation higher and dented the outlook for growth.
But even if shipping through the strait normalizes, higher inflation has already been largely “baked in” across many economies, Simon MacAdam, deputy chief global economist at Capital Economics, said in a note this week.
“It can take many months for higher energy and fertiliser prices to be passed along food supply chains to end-consumers,” MacAdam said. Prices of natural gas piped to households typically lag the upstream market by around three months, he said.
Oil prices retreated to around $80 a barrel on Friday, down from a peak of $118 in March when the war was at its height. Goldman Sachs cut its oil price forecast Tuesday, projecting Brent to average $80 in late 2026 and $75 in 2027, citing a faster-than-expected recovery in Persian Gulf crude flows.
Higher energy costs and upstream supply disruptions would take longer to feed through to the downstream food and energy sectors. A backlog of vessels waiting to transit the Strait of Hormuz could further delay a full recovery in freight flows.
The World Bank, which last week lowered its global economic growth forecast to 2.5%, the slowest pace since the pandemic, expects global inflation to climb to 4% this year, up from 3.3% in 2025, even if disruptions to oil flows ease in the coming weeks.
Fertilizer prices could jump as much as 38% this year as supply disruptions and shortages of key inputs from the Gulf ripple through agricultural markets, it said.
Europe could face particular pressure because natural gas storage levels remain historically low, MacAdam said, expecting inflation in Europe and Japan to rise by an additional 3 to 4 percentage points as U.S. liquefied natural gas export prices move higher.
The European Central Bank was the first major central bank to raise interest rates last week, its first tightening move in nearly three years.
Meanwhile, the Fed, under new Chairman Kevin Warsh, left short-term interest rates unchanged on Wednesday but raised its forecast for personal consumption expenditures inflation to 3.6% by December, from 2.7% projected in March. Nine of the 18 voting members expect at least one rate hike before the end of this year.
The trajectory underscores how the Hormuz crisis has altered the calculus for central banks trying to balance slowing growth against rising inflation.
The Bank of England also kept its policy rates unchanged but warned that “even in the event of prompt conflict resolution, there could be a logistical delay in restoring energy production and transportation.”

KINSHASA – Ebola patients are fleeing treatment centres in the Democratic Republic of Congo in search of food, underscoring how hunger has become one of the biggest obstacles to containing the virus.
Outbreak responders are “coming to us, knocking on our door and saying: ‘We need food assistance if we’re going to end Ebola,’” said David Stevenson, who runs the World Food Program’s operations in Congo and has spent three decades working in humanitarian emergencies.
“I’ve never seen anything like it.”
Government reports have documented more than 150 escapes from Ebola treatment and isolation facilities since late May.
In one incident, 11 suspected patients fled a hospital in Bambu, about 40km from the outbreak’s epicentre around the gold-mining town of Mongbwalu, because of inadequate nutritional support, according to the health authorities. Other reports have linked patient departures to food shortages and poor living conditions.
Even before the outbreak, eastern Congo was grappling with widespread displacement, conflict and one of the world’s worst hunger crises.
Now those pressures are colliding with efforts to contain a virus that has already infected almost 900 people, killing more than a quarter of them.
Food insecurity impacts almost 10 million people in the country’s eastern provinces, not only complicating efforts to isolate patients but also to monitor people exposed to the virus.
The health authorities are currently tracking about 6,400 people who may have been exposed to Ebola. Families asked to remain under observation often lose access to work, markets and other sources of income.
“If you confine people, they will need to be supported with food. And if they don’t get food, they will move,” said Olivier Nkakudulu, head of field operations in Ituri, the province that accounts for more than 90 per cent of confirmed cases, for the World Food Program.
The consequences can be especially severe when the person under observation is the household’s main provider.
“Just imagine if we put a single mother into isolation, what will happen to the children?” said Godfrey Ayena, national director of Food for the Hungry in Uganda.
Similar challenges can arise in child-headed or elderly-headed households, he said.
In much of the region, families typically provide food for hospitalised relatives, meaning Ebola isolation rules can abruptly cut patients off from their usual support networks.
The United Nations’ food assistance agency is now providing hot meals at Ebola treatment centres and delivering food to patients, monitored contacts and affected families.
This week, 590 hot meals were distributed in a single day to suspected and confirmed patients, contacts under observation and caregivers.
Health workers recall encountering similar challenges in previous outbreaks.
“When people don’t have food, it causes them to be desperate,” said Kenneth Kobba, a Ugandan public health physician preparing to deploy to eastern Congo, where he will respond to his fourth Ebola crisis.
‘Terrible choices’
Kobba recalled that during Uganda’s 2022 outbreak, some people repeatedly came to treatment units claiming to have symptoms because meals were available there, potentially exposing themselves to infection.
“Someone will come and tell you I have fever and headache,” he said. By the time test results came back, the person would already have received several meals.
Years of conflict in eastern Congo have disrupted agriculture, displaced millions of people and made it difficult for humanitarian agencies to reach vulnerable communities. Recent cuts to aid budgets have compounded those challenges, forcing relief organisations to balance competing priorities.
“This requires making terrible choices between the extremely hungry who are next to starvation and those who are very hungry and do not know where they’re going to get their next meal,” Stevenson said.
Jacques, 52, who declined to give his last name for security reasons, said he has been relying on churches in Beni to help feed his 14 children after fleeing fighting around Bukavu in South Kivu province.
Two weeks
A little over a week ago, his 5-year-old daughter began vomiting and bleeding from her ears. He brought her to Beni’s main hospital, where she died a few hours later. His wife is now in isolation at the same facility with Ebola.
Since arriving at the hospital, he has received a food kit from the World Food Program.
“That’s enough for two weeks, and after that what are we going to do to eat?” he said.
WFP is seeking US$175 million ( S$226.23 million ) until November for its Congo operations, including US$32 million earmarked for Ebola-related activities, according to Stevenson. The agency’s budget in the country has fallen by about a third over the past two to three years.
“The need to address the wider population is crucial, and we’re just not going to be able to end Ebola unless we address those needs,” he said. “It simply will not work.” BLOOMBERG