Is there a brown water advisory on Oahu right now?

Check the live status at the top of this page for current Oʻahu brown water advisories. Advisories are most common after heavy rain, especially along the south shore near the Ala Wai Canal, Waikiki, Ala Moana, and the North Shore near Waimea Bay and Sunset Beach where streams discharge into the ocean.

How does the Ala Wai Canal affect Oahu water quality?

The Ala Wai Canal collects storm runoff from a 16-square-mile watershed that includes Manoa Valley, residential neighborhoods, and commercial areas behind Waikiki. During heavy rain, the canal can overflow and discharge untreated sewage, urban pollutants, and debris directly into the ocean at the east end of Waikiki Beach. Documented sewage overflows have exceeded 500,000 gallons. Ala Moana Beach, immediately west of the canal mouth, is typically even more affected than Waikiki proper.

Which Oahu beaches are most affected by brown water?

Waikiki Beach and Ala Moana Beach are most affected due to the Ala Wai Canal. Kailua Beach is affected by Kawainui Marsh drainage. The North Shore beaches like Waimea Bay and Haleiwa are affected by stream outlets. Sandy Beach and Makapuu on the east side can also see brown water after heavy rain. Ko Olina's enclosed lagoons on the leeward coast are generally less affected by runoff.

What is the water quality on Oahu today?

Current Oʻahu water quality depends on recent rainfall and active advisories. Check the live advisory status at the top of this page for real-time information. After any rain, follow the 72-hour rule before swimming. Beaches near stream mouths and the Ala Wai Canal are the first to be affected and the slowest to recover.

How long does brown water last on Oahu beaches?

Brown water on Oʻahu typically lasts 1 to 3 days after heavy rain stops. Open-ocean beaches like Sandy Beach and Makapuu recover faster due to strong currents. Enclosed areas like Ala Moana and Kailua Bay take longer because of poor water circulation. The DOH recommends waiting at least 72 hours after rain stops and the beach has received full sunshine. The brown color clears before bacteria does, so clear water does not mean safe water.

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LIVE STATUS · OʻAHU

Oʻahu Brown Water Advisory

Live advisory status for every Oʻahu beach — Ala Wai Canal, North Shore streams, Windward drainage, and the 72-hour rule

Checking for active Oʻahu brown water advisories…

Oʻahu brown water advisory = stay out of the ocean. Rain flushes sewage from cesspools through the Ala Wai Canal, North Shore streams, and Windward side drainage into the sea, spiking bacteria up to 500% above safe limits.

⚠ The rule: Wait at least 72 hours after rain stops — even if the water looks clear and no advisory is posted. Clear water ≠ safe water.

Most affected on Oʻahu: Waikiki (Ala Wai Canal), Ala Moana (canal & harbor runoff), Kailua (Kawainui Marsh), Waimea Bay (river mouth), and Sandy Beach after heavy east-side rain.

The Ala Wai Canal Problem

The Ala Wai Canal is the single biggest driver of brown water advisories on Oʻahu. This man-made waterway runs along the back of Waikiki and empties into the ocean at the east end of Waikiki Beach. It collects storm runoff from a 16-square-mile watershed that includes Mānoa Valley, residential neighborhoods, and commercial areas.

During heavy rain, the canal overflows and carries untreated sewage, urban pollutants, and debris directly to the ocean. Documented sewage overflows have exceeded 500,000 gallons in a single event. The result is that Waikiki and Ala Moana are among the first beaches impacted during any rain event on Oʻahu.

If you are staying in Waikiki during a rain event, the safest option is to wait the full 72 hours. If you want to swim sooner, consider heading to Ko Olina’s lagoons on the leeward coast — they are enclosed, man-made, and less affected by runoff.

Oʻahu Brown Water Drainage Zones

Oʻahu’s geography channels rainfall through four distinct drainage zones, each affecting different beaches:

South Shore — Ala Wai Canal

The Ala Wai collects runoff from Mānoa, Palolo, and McCully and discharges at Waikiki. Affects Waikiki Beach, Ala Moana Beach, and Diamond Head Beach. The south shore is the most-watched area for brown water on the island.

North Shore — Stream outlets

Waimea River, Anahulu Stream (Halēʻiwa), and multiple smaller streams discharge at Waimea Bay, Sunset Beach, and Halēʻiwa Beach after heavy rain in the Koʻolau Mountains. North Shore brown water events are common in winter.

Windward Side — Marsh drainage

Kawainui Marsh (the largest wetland in Hawaii) drains toward Kailua Beach. Kahana Bay, Kualoa, and Waimanalo also receive stream runoff from the Koʻolau range. Kailua and Lanikai can see elevated bacteria after moderate rain.

Leeward Coast — Generally drier

Ko Olina, ʻEwa Beach, and White Plains receive less rainfall and have fewer stream outlets. Ko Olina’s man-made lagoons are particularly sheltered from brown water events. This side recovers fastest after island-wide rain.

Oʻahu Beach Brown Water Risk

South Shore

Waikiki Beach · Ala Wai Canal discharge point

Elevated

Ala Moana Beach · Canal & harbor runoff

High

Diamond Head Beach · Urban runoff from Kapahulu

Moderate

Hanauma Bay · Protected reserve, low runoff risk

Low

North Shore

Waimea Bay · Waimea River mouth

Elevated

Sunset Beach · Stream outlets along North Shore

Moderate

Halēʻiwa Beach · Anahulu Stream discharge

Elevated

Windward Side

Kailua Beach · Kawainui Marsh drainage

Elevated

Lanikai Beach · Adjacent to Kailua drainage

Moderate

Bellows Beach · Waimanalo stream proximity

Moderate

Waimanalo Beach · Stream runoff from Koʻolau

Moderate

Kualoa Beach · Stream outlets, enclosed bay

Elevated

Kahana Bay Beach · Kahana Stream discharge

Elevated

Makapʻuʻu Beach · Open coast, minimal streams

Low

Leeward Coast

Ko Olina Lagoons · Enclosed, man-made, sheltered

Low

White Plains Beach · Dry leeward coast

Low

ʻEwa Beach · Less rainfall, fewer streams

Moderate

East Side

Sandy Beach · Open coast, fast recovery

Moderate

How Long Does Brown Water Last on Oʻahu?

Oʻahu’s brown water duration depends on the beach location and rain intensity:

Fastest

Open coast beaches

Sandy Beach, Makapʻuʻu, and Ko Olina recover fastest due to strong currents and wave action flushing contaminated water offshore. Often clear within 24–48 hours after rain stops.

Moderate

North Shore & Windward beaches

Waimea Bay, Sunset Beach, Kailua, and Lanikai typically take 48–72 hours after rain stops. Stream mouth areas stay affected longer than open stretches.

Slowest

Ala Wai Canal zone

Waikiki and Ala Moana can remain affected for 72+ hours after heavy rain due to the canal’s slow flushing rate and poor circulation in Ala Moana’s reef-protected area.

Key takeaway

Clear water ≠ safe water. The brown color clears before the bacteria does. Always wait the full 72 hours even if the ocean looks normal again. When in doubt, head to the leeward coast.

Guide →

Swimming After Rain in Hawaii — 72-Hour Rule Explained

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⚠️ Important Disclaimer

Safe to Swim Hawaii is an independent passion project — it is not affiliated with the Hawaii Department of Health or any government agency. Water quality ratings on this site are estimates based on publicly available testing data and geographic analysis. They are not real-time measurements and may not reflect current conditions. “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 water quality conditions with the Hawaii Department of Health Clean Water Branch before entering the water. This site is for informational purposes only and should not be the sole basis for any swimming decisions.

This site is a work in progress and we want to make it better. If you notice something that isn't working right, have a suggestion, or want to share local knowledge about a beach, please reach out.

When in doubt, don't go out.