The state Department of Health is warning beachgoers about possibly contaminated water at Magic Island Lagoon. Concurrently, the city parks department says a water main break has shut down water to the Magic Island area of Ala Moana Beach Park, and water service is unavailable at its bathrooms, showers and drinking fountains until 5 p.m. today for repairs.

The department’s Clean Water Branch detected levels of enterococci at 178 per 100 milliliters during routine beach monitoring of the lagoon. Test results indicate potentially harmful microorganisms such as bacteria, viruses, protozoa, or parasites may be present in the water. Swimming at beaches with pollution in the water may make you ill, the branch said.

The state posted warning signs at Magic Island today.

Children, the elderly, and people with weakened immune systems are most likely to develop illnesses or infections after coming into contact with polluted water.

The most common illness associated with swimming in water polluted by fecal pathogens is gastroenteritis. Symptoms include nausea, vomiting, stomachache, diarrhea, headache or fever, according to the department.

The advisory will remain in effect until water sample results no longer exceed the threshold level of 130 enterococci per 100 milliliters.

Updates on water quality advisories are available at bit.ly/2FqNJyK.