The popular swimming pond at Lake Elmo Park Reserve will remain closed until Saturday morning after 25.5 hours of intensive chlorination treatment to kill any possible contamination from an organism that might have caused illnesses in recent swimmers.
Park maintenance staff worked through the night to ensure that chlorination levels remained high, John Elholm, the county's parks director, said Friday. The county closed the swimming pond Thursday after hearing reports of sickness.
Whether swimmers who experienced diarrhea picked up the bug while swimming in the pond hasn't been determined, county officials said.
Two people with laboratory confirmed cases of Cryptosporidium, an organism that causes gastro-intestinal illnesses, reported they swam in the pond in the two weeks before the onset of their illness. Two additional laboratory confirmed cases reported outside the incubation period also could also be related, Elholm said.
None of the cases required hospitalization, the county said.
"We've never had this before," said parks manager Mike Polehna. The level of chlorine will dissipate naturally, and when it lowers, swimmers will be allowed back into the pond, he said. "I think things should be in good shape," he said.
Under normal circumstances the county filters the Lake Elmo pond four times daily, Polehna said.
The Lake Elmo manufactured pond -- a few hundred yards from the lake by the same name -- draws thousands of swimmers a week. The pond has sand beaches and colorful umbrellas surrounding it, and Polehna said it's the most popular outdoor swimming beach in the metro area.
Kevin Giles • 651-925-5037 Twitter: @stribgiles