The state Health Department issued a high bacteria level advisory for Lanikai Beach on Wednesday, which is expected to remain in effect throughout today.

Enterococci levels of 2046 per 100 milliliters, more than 15 times the federally approved threshold of 130 enterococci per 100 milliliters, were detected at Lanikai on Wednesday. Test results take at least 24 hours.

“Children, the elderly, and people with weakened immune systems are the most likely populations to develop illnesses or infections after coming into contact with polluted water, usually while swimming,” said the Health Department in its advisory. “Fortunately, while swimming-related illnesses can be unpleasant, they are usually not very serious — they require little or no treatment or get better quickly upon treatment, and they have no long-term health effects.”

Gastroenteritis is the most common illness associated with swimming in water polluted by fecal pathogens.

Brown water advisories, meanwhile, were also issued for the island of Kauai and for Haleiwa and Punaluu beach parks on Oahu.

Updated water advisories, including brown water advisories, are available at 808ne.ws/waterupdates.