Closed Gray's Lake beach should re-open soon

The threat of E.coli has closed the beach for swimming at Gray's Lake in Des Moines.

But it likely will re-open soon.

The Des Moines parks and recreation department posted the message on social media Thursday after placing no-swimming signs on the beach Tuesday.

Recent water samples showed E.coli levels more than four times above the safe-beach threshold set by the Iowa Department of Natural Resources, according to city officials.

Water tests by the DNR measured 580 units of E.coli bacteria per 100 milliliters of water. The agency recommends not swimming at beaches with levels above 126 units per 100 milliliters.

But new lab numbers Thursday from the DNR showed E.coli in Gray's Lake had dropped to 75 parts per 100 milliliters, according to DNR spokesman Kevin Baskins.

"Those numbers are down below the advisory level," Baskins said.

Officials with the Des Moines parks and recreation department said Thursday afternoon the lake remained closed because they had not received updated figures.

"Once we get the all clear the beach will open. All we need to do is notify the public and pull the signs," Jen Fletcher, spokeswoman with the parks and recreation department, said.

Fletcher said the issue stems from recent heavy rainfall carrying runoff into the Raccoon River, which feeds Gray's Lake.

"Our department always errs on the side of caution and we look for the high levels to dissipate soon," Fletcher said. "This usually happens once a year."

Officials with the DNR said E.coli levels fluctuate rapidly and drastically.

The swimming area in Gray's Lake opened two weeks ago when the seasonal buoys were set in place.

Baskins said the concentration of E.coli tends to spike immediately following heavy rainfall. Sunlight can then quickly kill the naturally occurring bacteria from feces.

Goose poop or dog droppings can be a major contributing factor for high levels in waterways near parks, he said.

"All of it can be tied to runoff and what kind of practices you have on the landscape that either filter or prevent excess runoff in that water body," he said.

Gray's Lake was the only central Iowa swimming area monitored by the DNR with excessive levels of E.coli, according to recent data from the state agency.

"Your primary concern is ingestion in big amounts," Baskins said. "The other worry, not as big, is if you have an open wound and bacteria in the water."