Bacteria risk, DOH advisories, and stream discharge guide
📍 Kailua, Oʻahu — Windward Side
Kailua Beach is consistently rated as one of Oʻahu's best beaches for both beauty and water quality. On dry days with trade winds, the water is typically clear and bacteria levels are low. The beach is regularly monitored by DOH and has a good track record under normal conditions.
The key risk factor is Kaelepulu Stream, which drains from Kawainui Marsh (the largest wetland in Hawaii) into the south end of the beach. After rain, this stream carries elevated bacteria and can trigger DOH advisories. Localized advisories at Kailua typically affect just the south portion near the stream mouth.
Based on: DOH monitoring history, Kaelepulu Stream discharge, trade wind exposure, residential cesspool density
Wait at least 72 hours after heavy rain before swimming near the stream discharge. Kawainui Marsh absorbs enormous rainfall volumes and releases them slowly — bacteria can remain elevated for days after a storm. The north end of the beach recovers faster than the south end.
The northern section of Kailua Beach, toward Kailua Beach Park's main facilities, is further from the stream and recovers faster. Best choice after rain events.
The area near Kaelepulu Stream discharge at the south end is the most affected by rain events. Visible brown water plumes often extend 50-100 yards into the ocean. Stay out until the water clears.
The open-water area between Kailua Beach and the Mokulua Islands (Na Mokulua) typically has the clearest water. Kayakers and paddleboarders heading offshore generally encounter better conditions.
Free alerts for brown water advisories and bacteria warnings at Kailua and nearby beaches.
No spam. Just safety alerts for your trip.
⚠️ Important Disclaimer
Safe to Swim Hawaii is an independent project not affiliated with the Hawaii DOH. Ratings are estimates based on historical data — not real-time measurements.
Verify with the Hawaii DOH Clean Water Branch before swimming.
When in doubt, don't go out. 🤙