MERRIMACK – A state advisory warning of high E. coli levels at Wasserman Park has been lifted after tests showed the levels have returned to normal.

The warning, issued Friday, advised swimmers not to jump into Naticook Lake at the popular town beach due to E. coli levels that exceeded the state’s limit of 88 counts of E. coli per 100 milliliters.

It was the second advisory issued this summer at Wasserman, which sits on Naticook Road, But, like the first, the warning was quickly lifted after further tests were administered.

State officials lifted the advisory Tuesday morning, and swimmers returned to the park soon after, according to Sherry Kalish, the town’s parks and recreation director.

“People are back swimming, having fun,” Kalish said Wednesday. “The numbers fluctuate so greatly, they know there’s really nothing to worry about.”

High E. coli levels, which can cause intestinal illness, among other symptoms, can be result from a wide range of factors, from ducks in the water to even rain run-off, Kalish said.