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BIG ISLAND · HILO SIDE

Onekahakaha Beach Park

Water quality status and bacteria risk rating

📍 Hilo, east side Big Island

Checking live advisories…
⚠
If It Looks Brown, Don't Swim
Never enter the ocean when the water appears brown or murky, even if no advisory is posted. Hawaii is often slow to test beaches and update advisories — not every beach is monitored. After heavy rain, wait at least 72 hours and until the water clears before swimming.
Learn more about brown water advisories →
Historical Bacteria Risk
⚠ Historical rating — this is based on long-term testing data, not current conditions. The state of Hawaii is often slow to test beaches and update advisories. Always check the water yourself and avoid brown or murky water.
Moderate Risk 3 / 5

Onekahakaha Beach Park has a moderate bacteria risk. Located in Hilo — one of the wettest cities in the United States — this beach receives runoff from multiple streams on the rainy east side of the Big Island. After rain, water quality can degrade significantly as streams carry sediment and bacteria into the nearshore area.

The beach is known for its large, protected tide pool area created by a natural rock breakwater. These pools provide calm, shallow water popular with local families. However, the protected nature of the pools can trap runoff water, potentially prolonging elevated bacteria levels after storms. During dry stretches, conditions improve considerably.

Based on: DOH monitoring data, multiple stream inputs, Hilo rainfall patterns, protected tide pool geometry

⚠️ The 72-Hour Rain Rule

At stream-fed beaches like Onekahakaha, the Department of Health recommends staying out of the ocean for at least 72 hours after heavy rain. Hilo receives over 120 inches of rain annually, so this rule applies frequently. The tide pools may take longer to flush than open coast beaches. Check conditions and wait for clear water before swimming.

Onekahakaha Area Hotels — Historical Beach Water Quality
🏨 Grand Naniloa Hotel
Hilo bayfront, 10 min drive
Moderate
🏨 Hilo Hawaiian Hotel
Hilo Bay, 10 min drive
Moderate
Things to Do Nearby
Volcano National Park Tour
Guided volcano tour departing from Hilo
Book →
Hilo Waterfall Tour
Visit Hilo's stunning tropical waterfalls
Book →
Big Island Circle Tour
Full-day tour around the Big Island's highlights
Book →
Related Guides
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Spencer Beach Water Quality
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Swimming After Rain in Hawaii
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Hawaii Brown Water Advisory Guide
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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.

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When in doubt, don't go out. 🤙

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