COLUMBIA — High levels of E. coli shut down the swimming beach at a state park north of Columbia on Highway 63.
The public swimming beach at Finger Lakes State Park closed Wednesday until further notice because of elevated levels of E. coli bacteria, Park Superintendent Debbie Newby said.
According to a Department of Natural Resources news release, the Finger Lakes swimming beach had 1,119.9 colonies of E. coli per 100 milliliters of water, almost five times the acceptable limit.
"I've been working here for 12 years, and this is the first time I've seen those levels rise above 200 parts per million," Newby said, referring to the single-sample guideline of 235 colonies per 100 milliliters of water used by the Environmental Protection Agency and the Missouri Department of Natural Resources.
The Department of Natural Resources tests all of its swimming beaches weekly on Mondays and posts the results the following Wednesday. That means Finger Lakes beach will be closed for at least a week until further tests confirm that levels have dropped back below the limit.
The testing process involves taking two samples from the water a few feet from the beach on the left and right. If either sample is above the "bright line" standard of 235 colonies per 100 milliliters, the beach is automatically closed.
"We've been sitting around here scratching our heads wondering what could be causing it, but we don't have any ideas yet," Newby said.
Judd Slivka, a spokesman for the Department of Natural Resources, said the department has not identified a cause for the increase, but that bacteria levels often rise after rain storms when bacteria-rich material, including effluent from waste water plants and animal waste, is washed into bodies of water.
"This is a fairly common occurrence that has been highlighted by the combination of a wet spring and summer and the fact that we have elevated the profile of our testing efforts," he said.
The Department of Natural Resources created a website to track beach closures throughout the state.
Slivka said heavy rains during the weekend likely contributed to the test results, and high bacteria numbers in a single sample are not necessarily indicative of the quality of the entire body of water.
"E. coli is highly variable according to the temperature, depth and turbidity of the water," Slivka said. "You can take a high reading from one side of the boat, then take a reading from the other side, and get nothing."
Signs have been posted warning swimmers to stay off the beach until bacteria levels go down.
Although E. coli is relatively harmless to healthy adults, it can be dangerous to children, seniors and people with open wounds or weakened immune systems. Slivka advised swimmers to use their judgment when deciding when and where to swim, especially after heavy rains.
"I would encourage everyone to practice good hygiene and wash off after swimming in any body of water, whether it's a swimming pool or a lake in the park," Slivka said.