Algae is forming on the water in the newly refurbished reflecting pool by the Lincoln Memorial in Washington, D.C. (Bill O'Leary/WASHINGTON POST)

Less than a month after reopening, the Lincoln Memorial Reflecting Pool is full of algae, a sea of green overshadowing the nearly two-year, $34 million renovation of the famous site.

The National Park Service anticipated a “break-in period” in which problems would need to be addressed, spokeswoman Carol Johnson said, but no one expected the amount of algae that is there now.

Officials are working to remove the algae by increasing the level of ozone in the water to treat what is there and prevent more from growing. The agency plans a one-time removal of the algae, but first the ozone level needs to be fine-tuned, Johnson said.

How they’ll do that has not been determined, Johnson said, and the full cost of repairs is not yet known.

“We don’t want to go in there and remove it and have it re-bloom,” Johnson said.

Algae are organisms that can be found in most habitats, and they thrive on sunlight and heat. Park Service officials discovered them in the Reflecting Pool about a week after the reopening, during normal operations, Johnson said.

Some of the algae have been filtered out; most of what remain are dead. But it will take more than filters to keep the pool clear.

While the pool took its water from the city’s drinking system, the reconstruction allows it to take water from the Tidal Basin, saving the city 32 million gallons of water a year.

But because the pool is a smaller and shallower water source, the algae cells bloom more easily there.

“This is a direct consequence of the fact that this is a green project,” Johnson said. “The conditions are pretty good for algae, once it gets in there.”

There are no water-quality, health or safety concerns because of the buildup of algae, and the pumping and circulation system is working properly, Johnson said.

The problem is how it looks.

Visitors to the pool described it as similar to “split pea soup,” “muddy,” like the “surface of the moon” and “icky-looking.”

“It doesn’t look like a $34 million circulation job,” Jim Carroll, 85, of Wisconsin said as he looked out over the pool.

Most of the pool’s surface is clear, but the bottom is covered in algae. The end of the pool near the World War II Memorial has the most algae, clumped together, and Park Service workers were skimming the top there Tuesday.

“It doesn’t reflect well on the city at all,” Carolyn Rossinsky, 49, of Miami said as she sat near the pool.

“It looks like green fluff,” she added.

The pool was added after the Lincoln Memorial’s dedication in 1922, and over the years it leaked and cracked. The renovated pool opened Aug. 31, after being closed to the public since 2010.

“Maybe they need to call their engineers back,” Larry Kuba, 50, of Safety Harbor, Fla., said after he snapped some photos of the pool.

The park service said the project was an overall success, and the algae is just a small bump in the road.

“There’s a whole lot more than just the pool,” Johnson said. “The algae is just one thing that we’re going to have to deal with.”

Some visitors didn’t mind it too much, saying it wouldn’t put a damper on their visit to the District.

“It’s not a downer, as far as I’m concerned,” said Robert Chappell, 75, who lives near Toronto.

“It wasn’t a disappointment,” said Jake Starkel, 31, of Ronan, Mont.

But one D.C. resident visiting the pool on her lunch break said she found the algae “unpleasant” and “terrible.”

“I was expecting something different,” said Carol Reid, 51, of Southeast. “There should be something in place to deal with this kind of issue.”