Tibbetts Beach at Lake Sammamish State Park was approved to reopen on Friday, King County Public Health announced in the department’s Public Health Insider blog.

The public health department received reports earlier in the week that 15 people became ill with vomiting and diarrhea after swimming at Tibbetts Beach on Aug. 26. Symptoms had occurred within 24 hours of visiting the beach, leading health officials to believe that the likely cause was norovirus.

In a blog update on Friday, public health officials reported all water sample tests for norovirus and other indicators of fecal contamination and toxic algae came back negative.

“There does not appear to be an ongoing risk of illness associated with swimming in the lake,” the health department stated in the blog update.

The King County Department of Natural Resources and Parks collected samples on Monday from Tibbetts Beach, Tibbetts Creek and Idylwood Beach. Health officials reported Tuesday afternoon that Tibbetts Beach test results came back showing fecal coliform below the level of concern.

The health department also reported two other people got sick who had not gotten in the water, but were household members of people who did.

“These ‘secondary cases’ happen frequently with norovirus,” the department stated Friday. “Norovirus is a common and very contagious virus spread through food, water, and via surfaces like door knobs and tables, and is easily transmitted from person to person.”

The department provided general tips for public venue swimmers, including making sure babies wear leak-proof diapers and showering before using public recreational water facilities.

“Anyone who is suspected of having norovirus should take the utmost care to wash hands carefully to minimize risk of spread to others,” the health department stated. “And households that have people ill with norovirus may want to pay special attention to cleaning and disinfection.”

For more, visit the King County Public Health Insider blog online.