The state Health Department has issued a high bacteria advisory for Haleiwa Alii Beach Park on Oahu’s North Shore.

During routine beach monitoring, the department’s Clean Water Branch recorded enterococci levels of 531 per 100 milliliters in the park’s waters. The acceptable threshold is 130 enterococci per 100 milliliters.

“The advisory for this beach is posted because testing for enterococci indicate that potentially harmful microorganisms such as bacteria, viruses, protozoa, or parasites may be present in the water,” said the branch in its advisory. “Swimming at beaches with pollution in the water may make you ill.”

Gastroenteritis is the most common illness associated with swimming in water polluted by fecal pathogens is gastroenteritis, according to DOH.

Symptoms include nausea, vomiting, stomachache, diarrhea, headache or fever. Some other minor illnesses Other minor illnesses associated with swimming in polluted waters include ear, eye, nose and throat infections.

Children, the elderly, and people with weakened immune systems are the most vulnerable.