Cleanest O'ahu Beaches Right Now

Hawaii DOH’s September 2024 Beach Monitoring Program document lists approximately 407 BEACH Act beaches statewide and reports that approximately 167 were monitored in 2023; frequency varies by tier and resources, and Molokaʻi/Lānaʻi are not routinely monitored. Surfrider Foundation's volunteer Blue Water Task Force extends official coverage, with some overlap. Below are the worst recent BWTF readings within O'ahu's coverage:

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 O'ahu”), 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 complete swim decision. 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.

Sheltered lagoons remain subject to advisories

This table compares recorded advisory days for tracked beaches on Oʻahu. An island-wide advisory applies across its stated area, including sheltered lagoons. Clear-looking water or a protected setting does not override current DOH advice.

Check current DOH notices, posted signs and local conditions before entering the water. Historical rankings do not override an active advisory.

Related beach histories and guides: Ala Wai, Waikiki, Kailua, Lanikai, Hawaii cesspool guide, Ko Olina's, Sunset, Haleiwa, Waimea Bay, Ko Olina's four man-made lagoons.

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 O’ahu beach has the cleanest water right now?

Ala Moana Beach Park is the top-ranked tracked beach in this table, with 13/30 days advisory-free. This compares recorded advisory days among tracked beaches; it does not establish current water quality or explain the causes of a beach’s advisory history.

Does a sheltered lagoon override an advisory?

No. Check current DOH status and posted signs for Ko Olina. This ranking does not test lagoon water or establish that a location under advisory is clean.

Does ’cleanest’ mean you should swim on O’ahu?

No. This ranking compares days under posted Hawaii DOH advisories in a tracked sample; it does not directly measure all bacteria conditions or swimming safety. A beach can rank high here but still have physical hazards like strong currents, shore break, rip currents, or no lifeguards. Always check current DOH advisories and local surf/current conditions before entering the water.

Which side of O’ahu has the best water quality overall?

This table does not establish a permanently cleaner side of Oʻahu. It compares recorded advisory days for the tracked beaches in the current 30-day window. Use current DOH notices and local conditions for a swim decision.