City parks officials are planning to close Hanauma Bay Wednesday after the state health department found bacterial levels exceeded its established threshhold.
The parking lots, visitor center and upper viewpoint will be open during regular hours, the parks department said in a news release.
The health department's clean water branch found levels of enterococci were 222 per 100 milliliters. The threshhold is 130 enterococci per 100 milliliters. The finding of enterococci indicates potentially harmful microorganisms like bacteria, viruses, protozoa, or parasites could be present in the water and could make swimmers sick.
The young, the elderly, and those with weakened immune systems are most at risk if they swim in polluted water.
Officials hope to reopen the nature reserve on Thursday or after testing shows the waters are safer.
The closing follows last week's influx of box jellyfish, which shut down Hanauma Bay to visitors.