The state Health Department issued a high bacteria advisory for Kailua Beach Park late Thursday afternoon, which remains in effect today.

During routine beach monitoring, the department’s clean water branch detected enterococci levels of 453 per 100 milliliters, more than three times the threshold level of 130 per 100 milliliters.

Potentially harmful microorganisms such as bacteria, viruses, protozoa, or parasites may be present in the water, according to the Health Department.

Children, the elderly and people with weakened immune systems are the most likely to develop illnesses or infections after coming into contact with polluted water, the Health Department said, usually while swimming. While swimming-related illnesses can be unpleasant, they are usually not very serious, require little or no treatment or get better quickly upon treatment.

Signs have been posted at the beach, and the advisory remains in effect until water samples no longer exceed the threshold level of 130 enterococci per 100 milliliters.

Updates are available at 808ne.ws/waterupdates.