DOH monitoring, advisory areas, and the cleanest beaches on Maui
Maui’s water quality story is largely a tale of two coastlines. The west and south shores — Kaʻanapali, Wailea, Makena — sit in the island’s rain shadow and consistently have some of the best beach water quality in the state. The north shore and central Maui coastlines face more frequent advisories due to urban and agricultural runoff from the heavily developed Kahului-Wailuku corridor and streams draining the rainy windward slopes of Haleakalā.
The Hawaii DOH Clean Water Branch tests Maui beaches on a regular schedule, with additional sampling after significant rain events. Results are posted publicly and feed into the advisories at safetoswimhawaii.com.
The leeward shores of Maui receive little rainfall and have minimal runoff infrastructure. These beaches typically show conditions favorable for swimming under normal dry conditions. Post-rain caution still applies near any stream outlet.
Kihei has multiple beach parks along its length. Southern Kihei parks near Kamaole tend to perform better than northern Kihei, which is closer to runoff from the central valley. All can be affected by post-rain events.
Maui’s north shore receives heavy rain and has multiple stream mouths draining agricultural and residential land. Hoʻokipa, Baldwin Beach, and areas east toward Hana can see temporary advisories especially in winter.
Maui County has more than 12,000 cesspools statewide — simple pits in the ground that receive raw sewage. Unlike septic systems with treatment infrastructure, cesspools allow untreated waste to leach directly into the ground. Near the coast, this can reach the ocean through groundwater, particularly during heavy rainfall.
A 2020 state law requires all cesspools in Hawaiʻi to be converted by 2050. Conversion is ongoing but slow. Areas with high cesspool density — particularly rural and semi-rural Maui — are more likely to see elevated bacteria counts after heavy rain even far from obvious point sources.
Following the August 2023 wildfires, the DOH conducted extensive testing of nearshore waters around Lahaina. Burned debris, ash, and fire retardant chemicals introduced contaminants beyond normal bacteria. Monitoring has continued. Check current advisory status for any West Maui beaches near the fire zone before swimming, and look for official DOH communications on any ongoing advisories in that area.
Dry season on the leeward coasts. West and south Maui beaches at their best. North shore can still get rain but advisory rates tend to be lower overall. Best time for Molokini snorkeling — calmer seas and better visibility.
Humpback whales concentrate in the Maui Nui basin (between Maui, Molokaʻi, Lānaʻi, and Kahoʻolawe). You can often see them from the beach at Wailea and Kaʻanapali during this period. Winter also means more rain and more advisory activity on the north shore.
Wait 48–72 hours after significant rain before swimming at beaches near stream mouths or urban runoff areas. Even leeward beaches can be affected if rainfall was unusually heavy.
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⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with DOH or any government agency. Information is for educational purposes only and is not real-time measurements.
Always verify conditions with the Hawaii DOH Clean Water Branch before entering the water.
When in doubt, don't go out. 🤙