interior

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.

In California, ozone nanobubbles also have been used in a project to improve water quality in the Tijuana River. The 120-mile river that runs near the border in northern Mexico and Southern California was the site of a pilot study in 2025. The U.S. section of the International Boundary and Water Commission reported that the nanobubbling reduced “odors and bacteria,” but the project concluded prematurely after a flood swept some of the instrumentation into the river.

Pakistan Interior Minister Mohsin Naqvi met Iranian President Masoud Pezeshkian in Tehran to discuss regional security and bilateral ties.

The talks also focused on growing tensions between Iran and the United States following the collapse of Pakistan-mediated negotiations

BOISE, Idaho — Former Idaho Gov. and U.S. Interior Secretary Dirk Kempthorne has died at age 74, his family said in a written statement Saturday.

Kempthorne died Friday evening in Boise, the statement said. No cause was given. He had been diagnosed with colon cancer last year.

“Beyond his public service, he was a devoted husband, father, and grandfather whose greatest joy came from time spent with family and the people he met along the way,” his family said. “He had a rare gift for truly seeing others — remembering names, stories, and the small details that made each person feel known and valued.”

Kempthorne, a moderate Republican, was elected mayor of Boise in 1985 at age 34, and he was credited with revitalizing the downtown by securing an agreement to build a convention center and promoting other development. He served seven years before winning the U.S. Senate seat vacated by Sen. Steve Symms in 1992.

During his time in Washington, he authored legislation — signed by Democratic President Clinton — to end unfunded federal mandates on state and local governments.

Rather than run for reelection in 1998, he entered an open election for governor, trouncing his Democratic opponent by garnering more than two-thirds of the vote.

President George W. Bush appointed him Interior secretary in 2006, a position he held until the end of Bush’s presidency — and during which he lived on a houseboat docked in the Potomac River.

“Dirk was one of the finest public servants I ever knew because he was one of the finest men,” former President George W. Bush said in a written statement Saturday. “He was considerate, smart, and capable. Dirk loved our lands and waters, and as Secretary of the Interior, he was an effective steward of our natural resources.”

He protected polar bears

Environmentalists often found Kempthorne too accommodating to industry, citing his efforts to push oil and gas development in the Gulf of Mexico and off Alaska. More than 100 conservation groups opposed his nomination as Interior secretary, saying that as a senator he had voted to eliminate federal money for recovery of the endangered wolf, to open the Arctic National Wildlife Refuge to oil and gas exploration, and to sell off federal public lands.

Yet in 2008, he bucked other advisers in the White House by insisting that the polar bear should be listed as a threatened species under the Endangered Species Act because of the loss of sea ice in the Arctic. He was prepared to resign over it when Bush decided to back him.

“As Governor, Dirk left an enduring mark on our state,” Idaho Gov. Brad Little said in a written statement. With the partnership of his wife, Patricia, Kempthorne “championed children and families, strengthened public education, and led transformational investments in our transportation system that will benefit Idahoans for generations.”

After leaving the federal government, he became the chief executive of a trade association of life insurance companies.

He helped Afghan refugees

In a 2023 question-and-answer session with the George W. Bush Presidential Center, Kempthorne recalled helping evacuate nearly 400 U.S. citizens and Afghan allies from Afghanistan two years earlier, as many were being sought by the Taliban following the U.S. military’s chaotic withdrawal. Kempthorne and others worked frantically for months to raise money and garner the support of diplomatic channels to charter buses and an Airbus A340 to help resettle the evacuees in the U.S. and Canada.

At one point, with the flight fully booked, the organizers received a list of more people who needed to leave urgently.

“That night, at a total loss for answers, alone, I knelt in prayer,” Kempthorne recalled. “I said, ‘Dear God, we cannot leave these people behind, please give a path forward.’”

He said he then had a vision of Mother Mary holding the infant Jesus. It gave him an idea: The babies on the flight didn’t need their own seats, as their parents could hold them. The organizers confirmed that with the airline and were able to add an additional 50 people to the flight, Kempthorne said.

Kempthorne was born in San Diego and grew up in Spokane, Wash. His father was a regional representative for Maytag, the appliance company. His mother, a homemaker, once worked as a secretary for the Legislature in Nebraska, her home state.

Kempthorne attended San Bernardino Valley College in California before transferring to the University of Idaho, where he served as student body president and met Patricia, his future wife. After graduation he worked as executive assistant to the director of the Idaho Department of Lands before joining the Idaho Home Builders Assn. as the executive vice president.

Kempthorne is survived by his wife, as well as their children Heather and Jeff and their families.

Johnson writes for the Associated Press. Johnson reported from Seattle.