A data-driven comparison using DOH monitoring, Surfrider testing, and Hui O Ka Wai Ola coastal water quality data. South Maui and West Maui have fundamentally different water quality profiles.
Wailea and the South Maui coast have consistently better water quality than Ka’anapali and West Maui. The difference comes down to geography: South Maui is the driest coast on the island with minimal stream runoff, while West Maui has multiple perennial streams, higher turbidity, and more pollution sources.
That said, neither area is immune. Wailea Beach recorded bacteria of 384/100mL in November 2019 (nearly 3x the safe limit), and Ulua Beach hit 137 in September 2023. No Hawaii beach is guaranteed safe 100% of the time, especially after rain.
The Wailea–Makena corridor sits on Maui’s dry leeward coast. Annual rainfall ranges from 10–20 inches — compared to 400 inches in parts of East Maui. The region has only one significant stream (Waikapu), and it deposits into Kealia Pond, a natural settling basin, before any water reaches the ocean. This means almost no land-based runoff reaches resort beaches during normal conditions.
The Hui O Ka Wai Ola monitoring program, which tests 24 South Maui sites from Maalaea to Ahihi Kinau every 2–3 weeks, has documented that turbidity is not a significant issue on this coast. Combined with open-ocean exposure and strong currents that flush the shoreline, South Maui beaches test clean in the vast majority of samples.
Source: Hui O Ka Wai Ola 2016–2018 Coastal Water Quality Report; Maui County Shoreline Access
Ka’anapali and the West Maui coast receive significantly more rainfall and have multiple perennial and intermittent streams carrying sediment, nutrients, and pollutants to the shore. Hui O Ka Wai Ola found that all West Maui monitoring sites exceeded the state turbidity standard of 0.2 NTU. The causes include streams running through areas of fallow agriculture, erosion from invasive species, and coastal development.
Hanakaoo Beach Park (“Canoe Beach”), immediately south of the Ka’anapali resort strip, is the most vulnerable point. It recorded 1,298 enterococci per 100mL on February 14, 2026 — ten times the safe limit. Previous advisories include 238/100mL in December 2019 and 137/100mL in January 2020.
Important context: Ka’anapali Beach proper, where the Sheraton, Hyatt, and Westin sit, has different water dynamics than Hanakaoo. The Sheraton at Black Rock (the northern end) is the farthest from Hanakaoo’s issues. But they’re on the same continuous coastline, and during heavy rain events the entire coast can be affected.
Source: Hui O Ka Wai Ola 2016–2018 Report; DOH advisories via Maui Now; Surfrider Maui BWTF
After the August 2023 fires, Surfrider’s Maui Chapter conducted two rounds of post-fire water quality testing along the Lahaina coast (January and June 2024), analyzing for heavy metals and polycyclic aromatic hydrocarbons. They found no evidence of fire-related contamination that would put human health at risk from ocean recreation. The Hawaii DOH subsequently set up quarterly monitoring that has confirmed these findings.
Source: Surfrider Maui Post-Fires Coastal Water Quality Monitoring Program, 2024
We want to be transparent: South Maui is not perfect. DOH routine monitoring has detected bacteria exceedances at Wailea-area beaches on at least two occasions:
Wailea Beach — November 2019: 384 enterococci per 100mL (nearly 3x the safe limit of 130). The advisory was lifted after follow-up sampling returned to normal.
Ulua Beach — September 2023: 137 enterococci per 100mL (slightly above the 130 threshold). Ulua sits between the Grand Wailea and the Andaz Maui.
These events are rare compared to the frequency of advisories on West Maui, but they demonstrate that no beach in Hawaii is guaranteed safe at all times. Even on the dry South Maui coast, localized events can temporarily elevate bacteria levels. Always check for active advisories.
Source: DOH Clean Water Branch advisories reported by Maui Now (Nov 27, 2019; Sep 16, 2023)
All South Maui resort hotels sit on the same dry leeward coast with minimal runoff:
Water quality varies along the West Maui coast. Location within the strip matters:
Hawaii DOH Clean Water Branch — Tests Tier 1 beaches weekly, including Ka’anapali, Hanakaoo, Wailea. Issues public advisories when bacteria exceeds 130/100mL. Funded by EPA BEACH Act grants (currently threatened with elimination in the FY2026 federal budget proposal).
Hui O Ka Wai Ola — Citizen-science program monitoring 41 sites across West and South Maui every 2–3 weeks for turbidity, nutrients, temperature, pH. The most comprehensive Maui-specific coastal monitoring, with data from 2016 to present.
Surfrider Foundation Maui — Blue Water Task Force tests surf spots and stream mouths monthly. Their 2024 report found Maui’s coastal water quality met standards more often than Oahu or Kauai. Post-fire testing confirmed Lahaina coast is safe for recreation.
As of 2024, DOH agreed to continue testing Tier 1 beaches even during Brown Water Advisories, closing a data gap that Surfrider identified.
Book South Maui. The Wailea–Makena corridor is the safest stretch of coastline on Maui. If you want West Maui scenery, Kapalua Bay (Ritz-Carlton, Montage) is the exception with excellent water quality.
Ka’anapali tests within safe limits most of the time during dry weather. Key things to know:
• Avoid swimming for 72 hours after heavy rain. West Maui’s streams flush pollutants to the coast. See our rain safety guide →
• Avoid Hanakaoo Beach Park after any rain. It’s the most vulnerable beach in the resort area.
• The Sheraton end (Black Rock) is better than the Hyatt end for water quality due to distance from drainage.
• Check for active advisories at the DOH Clean Water Branch before swimming.
The gap between South and West Maui widens during wet season (November–March). South Maui stays relatively dry even during winter storms, while West Maui gets significantly more rain and runoff. Read more about seasonal patterns →
Hawaii DOH Clean Water Branch — Beach monitoring, weekly Tier 1 sampling, advisories. eha-cloud.doh.hawaii.gov
Hui O Ka Wai Ola — 41 sites, West and South Maui, 2016–present. huiokawaiola.com
Surfrider Foundation Maui — BWTF 2024 Hawaii Report; Post-Fires Monitoring. maui.surfrider.org
PacIOOS / UH — Water quality data distribution. pacioos.hawaii.edu
Maui Now — DOH advisory reporting (Hanakaoo Feb 14, 2026; Wailea Nov 27, 2019; Ulua Sep 16, 2023).
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent passion project — not affiliated with the Hawaii Department of Health, Hui O Ka Wai Ola, Surfrider Foundation, or any government agency. Assessments are based on publicly available data and geographic analysis. They are not real-time measurements. “No DOH Alerts” means no advisory is currently posted — it does not mean the water was tested and found safe. DOH only monitors a fraction of Hawaii’s beaches, and some areas have no regular testing at all.
Always verify current conditions with the Hawaii Department of Health Clean Water Branch before entering the water.
When in doubt, don’t go out. 🤙