PORT ORCHARD — Horseshoe Lake County Park is set to reopen Tuesday following reports in July of norovirus infections in lake swimmers.

The park closed August 1 after the Kitsap Public Health District received reports of people experiencing gastrointestinal illnesses after visiting the park in late July.

Further investigation by the county found that 155 people had fallen ill and that the majority of them visited the park on July 29. One person tested positive for a norovirus infection.

A representative of the Kitsap Public Health District said the decision to reopen the beach was due to the incubation period for norovirus being over.

John Kiess, environmental health director, said they believe norovirus was introduced into the lake via an already sick swimmer. After the swimmer shed the virus into the water, an outbreak occurred. With the incubation period for norovirus having passed without any additional people becoming sick, the decision was made to reopen the beach.

The last reported illness onset date was August 3.

Kiess noted that those who are feeling ill should refrain from swimming in public places because some illnesses can spread that way.

Based on the onset of symptoms and incubation period, it is believed that a number of those reporting illness are considered “secondary cases” – people who got sick after exposure to another ill person who had visited the swimming beach during the time period around July 29.