Cleanest Big Island Beaches Right Now

How This Ranking Is Calculated

Every Hawaii Department of Health advisory is a public record — Beach Advisories are issued when bacteria levels at a monitoring station exceed the EPA recreational threshold of 130 CFU/100 mL enterococcus, and Brown Water Advisories are issued when storm runoff makes coastal water visibly turbid.

We count the number of days each beach has been under any DOH advisory in the last 30 days. Fewer days under advisory means a higher rank. When a DOH advisory is island-wide (“Brown Water Advisory, Island of Big Island”), every monitored beach on that island is counted as under advisory for those days. When an advisory is station-specific, only the matching beach is counted.

The ranking measures water quality exposure only — days under advisory. It is not a swim-safety rating. A beach can rank high here but still have strong currents, shore break, rip currents, or no lifeguards. Always check the individual beach page for physical-hazard information and live DOH status before you swim.

Why the Kohala Coast has Hawaii's cleanest beach water

The Big Island's west coast holds the statewide #1 spot almost every month. The factors stack unusually well:

• Under 10 inches of rain per year. The Kohala Coast — home to Hapuna, Mauna Kea Beach, Anaehoomalu Bay (A-Bay), and Spencer — is among the driest coastal climates in the United States. Mauna Kea and the Kohala mountains block weather from the northeast; Haleakala on Maui blocks it from the southwest. Less rain = almost no runoff = almost no Brown Water Advisories.
• No significant streams reach the resort beaches. The Kohala watershed drains through inland gulches that dissipate before reaching the coast. Unlike O'ahu's Ala Wai or Kaua'i's Hanalei, there's no perennial stream discharging into the Kohala beaches.
• Resort-grade wastewater infrastructure. Four Seasons Hualalai, Mauna Lani, Fairmont Orchid, Westin Hapuna, and Waikoloa all run modern wastewater treatment. The Kohala Coast resort corridor has effectively zero cesspool exposure — unusual in Hawaii, where roughly 88,000 cesspools provide a year-round bacteria floor on most other coastlines.
• Kona Coast is intermediate. Magic Sands, Kahalu'u, and the Kailua-Kona corridor get more rain (about 25-30 inches annually) and have occasional stream exposure. They still rank well, but several positions below Kohala.
• Hilo side is the opposite story. Honoli'i and the Hilo coastline catch 130+ inches of rain per year. Wailuku River, Wailoa, and Waiakea streams discharge into the bay. Hilo-area beaches spend the most days under Brown Water Advisory of any Big Island location.

Trip-planning implication: if your priority is consistent water quality on the Big Island, the Kohala Coast is the answer almost year-round. Hilo-area visits require flexibility — check live BWA status before planning ocean time there.

Data Sources

This ranking is built from:

• Hawaii DOH Clean Water Branch public API — Beach Advisory and Brown Water Advisory events, including bacteria Count values when an advisory is issued.
• DOH station registry — the official list of monitoring stations, mapped to each beach page.
• EPA Recreational Water Quality Criteria — the 130 CFU/100 mL enterococcus threshold referenced throughout.

Every beach in this ranking has its own page with the 30-day daily-bar chart showing exactly which days were under which kind of advisory, plus live DOH status. Click the beach name to see its full history.

Which Big Island beach has the cleanest water right now?

Based on the last 30 days of Hawaii DOH advisory data, Anaehoomalu Bay (A-Bay) is currently ranked #1 on the Big Island with 30/30 days clean. The Kohala Coast beaches (Hapuna, Mauna Kea, Anaehoomalu, Spencer) consistently sweep the top of this ranking — that coast gets under 10 inches of rain per year and has no significant streams reaching the resort beaches.

Why does the Kohala Coast rank cleaner than most of the U.S. coast?

Three factors stack: (1) Under 10 inches of annual rainfall — among the driest coastal climates in the country. (2) No perennial streams reach the Kohala resort beaches, so even occasional rain doesn't produce runoff events. (3) Resort-grade wastewater infrastructure with zero cesspool exposure, unlike most of Hawaii. The combination is unusual statewide and unusual nationally.

Does ’cleanest’ mean safe to swim on the Big Island?

No. Water quality ranks bacteria and advisory frequency — not physical hazards. Hapuna can have powerful shore break in winter. Kahalu'u has sharp reef in shallow water. Magic Sands has seasonal large waves. Always check physical conditions and DOH advisories together before swimming. See each beach page for its specific hazard profile.

Is the Hilo side really that different from the Kohala Coast?

Yes — structurally. The Kohala Coast averages under 10 inches of rain per year. The Hilo side averages over 130 inches. Honoli'i Beach and the Hilo coastline sit at the receiving end of that rainfall, with several perennial streams discharging nearby. During the wet season, Hilo-area beaches can spend most of the month under Brown Water Advisory while Kohala Coast beaches are advisory-free. Plan Hilo beach time around the forecast.