The National Park Service is draining and cleaning the reflecting pool at the Lincoln Memorial in Washington, D.C., after the deaths of around 80 ducklings. Authorities say the birds were killed by a parasite that live in the snails found in the water.
The first batch of the dead ducklings was discovered May 20 and the rest were found over a two-day period. Necropsies by the U.S. Geological Survey’s National Wildlife Health Center determined they had died of “high levels” of microscopic parasites that develop in snails living in the pool, according to a statement from the park service. The parasites are ingested by the ducks when they eat the snails. The deaths followed a heat wave in D.C.
Snails and the parasites have always been in the pool. But experts have speculated that the recent hot spell may have contributed to an increase in the parasites as the ducklings are more vulnerable than older ducks.
“There have been snails in there for as long as anyone can remember. The aquatic environment is a perfect habitat for them,” National Park Service spokesman Mike Litterst told the local DCist. “But why now as opposed to any other time? We’re probably really never going to know why now or what the cause of this was.”
Officials first tried to treat the water with chemicals but they weren’t effective enough to “fully reduce the parasite and snail populations” and stop additional duck deaths.
The parasites pose little to no risk to humans. If they manage to burrow under the skin they can cause an allergic rash — “swimmer’s itch” or cercarial dermatitis — but only if someone wades or swims in the water for a sustained period. Neither activity is allowed in the pool.
The pool and memorial, which have served as a backdrop to countless rallies, is being drained Sunday and will be refilled by June 19, officials said.
The Lincoln Memorial pool was completely rebuilt in 2012 with an improved water conservation system. Soon after the renovation was complete the pool had to be drained again and cleaned at a cost of $100,000 to deal with a massive algae bloom.
Just last month, officials installed ramps for ducks at the Capitol Reflecting Pool, making it easier for the birds, especially ducklings, to climb in and out of the water.