The plan is to 'super chlorinate' the pool to make sure a potential illness-causing organism isn't in the water.
The Lake Elmo Park Reserve swimming pond -- possibly the most popular beach in the metro area -- has closed for at least a day to allow for treatment for a potential organism that might have caused illnesses in recent swimmers.
Whether swimmers who are experiencing diarrhea picked up the bug while swimming in the pond hasn't been determined, county officials said Thursday, but they have decided to "super chlorinate" the pond to eradicate any bug in the water.
"Park visitor safety is our main concern," said John Elholm, parks director.
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.
High levels of chlorine needed to kill potential organisms will mean that the pond will be closed at least through noon Friday, said parks manager Mike Polehna. The level of chlorine will dissipate naturally, and when it lowers, swimmers will be allowed back into the pond.
The county filters the Lake Elmo pond four times daily, Polehna said.
The county's Public Health and Environment staff will provide signs to inform swimmers that anyone who has diarrhea should not swim for two weeks after symptoms resolve, Elholm 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.
Kevin Giles • 651-925-5037 Twitter: @stribgiles