PORT ORCHARD — The Kitsap Public Health District is investigating approximately 120 reported illnesses that have been linked to swimming in Horseshoe Lake at the county’s park in South Kitsap.

Because those swimming at the lake were exhibiting signs of a norovirus infection, the swimming beach at the lake was closed by county public health officials Wednesday, Aug. 1.

The public health district and Kitsap County Parks and Recreation Department said the park’s swimming beach will be closed indefinitely while those reports are investigated. Callers reported having gastrointestinal illnesses after swimming at the lake last weekend.

The county departments haven’t confirmed finding laboratory evidence of a specific virus or bacteria responsible for the illnesses, their symptoms are consistent with norovirus. The public health district said that in most cases it is difficult to identify the cause of this type of illness from lake water samples. Identification can be confirmed from human stool samples, officials said.

People who visited Horseshoe Lake County Park since Saturday, July 28 and who become ill with diarrhea, vomiting and/or stomach cramps are asked to call the health district at 360-728-2205 to report their illness, the number of people affected and which day, or days, they were at the park. Reports also can be made online at kitsappublichealth.org/about/health-concern.php.

In a public health district news release, officials said norovirus symptoms usually will improve after one or two days. If you are experiencing nausea, vomiting, diarrhea and/or stomach cramps, it is best to stay home for at least 48 hours after symptoms resolve. Good handwashing and keeping surfaces clean at home will help keep family members healthy, officials said.

If symptoms don’t improve within 24 hours, a health care provider should be consulted.