Hawaii health officials have issued brown water advisories across the islands as the state deals with the aftermath of a Kona Low storm, with an island wide warning on Kaua’i and further affected areas on O’ahu, Maui and the Big Island. The Hawaii Department of Health Clean Water Branch said heavy rainfall and runoff have kept coastal waters contaminated in several areas.
The storm moved through the islands earlier last week, bringing heavy rain that washed soil, waste and debris into streams and then into the sea. Officials said the brown water advisories sit on top of lingering effects from a wet March. Fox Weather reported that this was the third Kona Low storm in a month, a run of wet weather that has left ground saturated and drainage systems struggling to cope.
Health officials warn that brown water conditions can pose serious risks to swimmers and surfers. Their advice: “If the water is brown, turn around.” Runoff from heavy rain can carry sewage, pesticides and animal waste into the ocean, raising the risk of exposure to bacteria such as E. coli and salmonella. Storm conditions can also wash debris into coastal waters, while murky water may attract marine life, including sharks.
Officials recommend staying out of brown water for at least 48 to 72 hours after rainfall ends, though that timeline may be extended while unsettled weather continues and ground stays saturated. Authorities advise avoiding water that looks brown or murky even if advisories have been lifted. Travellers should check local updates, since advisories are lifted beach by beach once water quality improves.
Kaua’i flash flood warning and road closure
On Kaua’i, the weather threat turned acute on October 31, when the National Weather Service in Honolulu issued a flash flood warning at 1:20 p.m. Hawaii time, in effect until 2:45 p.m. that day. At 1:20 p.m., radar and automated rain gauges showed heavy rain falling over the eastern slopes of Kaua’i at a rate of 1 to 3 inches per hour. Flash flooding was ongoing or expected to begin shortly, especially near the Hanalei Bridge on Kuhio Highway and near the mouth of the Wailua River.
Law enforcement closed Kuhio Highway near the Hanalei Bridge. The warning covered small creeks and streams, urban areas, highways, streets and underpasses, as well as other poor drainage and low lying areas, and it listed the entire island of Kaua’i among the locations that could flood. The Weather Service warned that most flood deaths occur in vehicles, and told people to turn around rather than drive through flooded roads.
Why brown water stays unsafe after rain
Brown water is not just discoloured water. The colour comes from soil and runoff, and that runoff can carry contaminants from roads, farms, cesspools and animal waste. Bacteria levels in coastal water often stay high after the water starts to look clearer, which is why officials use test results and a waiting period, rather than appearance alone, to decide when an advisory ends.
People who swim in contaminated water risk stomach illness, skin infections, ear infections and eye irritation, depending on the contaminant and the exposure. Children, older adults and people with open wounds or weakened immune systems face higher risk. Health officials do not list a single illness for brown water exposure, because the mix of bacteria and chemicals in runoff varies from place to place and from storm to storm.
What to do until brown water advisories lift
Until advisories lift, the safest course is to stay out of brown water in affected areas and to keep children and pets away from runoff and streams. Anyone who does come into contact with flood water should wash hands with soap and clean water, and throw away food that has come into contact with flood water. People should listen for news reports on whether the local water supply is safe to drink.
After a flood, households should check for damage, avoid downed power lines and report them to emergency services, and clear gutters and drains once it is safe to do so. Kaua’i officials have also urged residents still repairing damage from Hurricane Lowell to secure tarps, loose construction materials and storm debris that flood water could sweep away or push into drainage systems.
The advisories come as Hawaii recovers from severe flooding caused by back to back Kona Low storm systems that drenched the state in recent weeks. Those storms triggered evacuations across parts of O’ahu, where residents were forced from their homes amid rising floodwaters. Water quality testing will decide, beach by beach, when brown water advisories can lift and swimming is safe again, and officials have said travellers should monitor local updates rather than assume a whole island is clear because one beach has reopened.