Beach · Maui County · HI
Is Oneloa Beach (Big Beach) safe to swim?
Recent heavy rain may have spiked bacteria since the last clear sample.
Updated July 19, 2026 · Hawaii beach program (EPA BEACON)
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Know before you get in at Oneloa Beach (Big Beach).
Get an alert the day a bacteria or algae advisory goes up.
What's in the water at Oneloa Beach (Big Beach) right now
As of July 19, 2026, Oneloa Beach (Big Beach) in Maui County, Hawaii carries a swim caution. Blue-green algae are not currently monitored at this water. No fecal-bacteria advisory is posted (state beach program). Rainfall over the past week totaled 2.6 in, which can wash bacteria and nutrients into the water.
Blue-green algae at Oneloa Beach (Big Beach)
Oneloa Beach (Big Beach) is a lake in Maui County, Hawaii. Blue-green algae are not currently monitored at this water.
Blue-green algae (cyanobacteria) blooms are most common from midsummer into early fall, when the water is warm, calm, and rich in nutrients from runoff. They can produce toxins that make people sick and can be rapidly fatal to dogs, so skip water that looks green, scummy, or like spilled paint, and keep children and pets out of it.
Frequently asked: swimming in Oneloa Beach (Big Beach)
- Is it safe to swim in Oneloa Beach (Big Beach) right now?
- Oneloa Beach (Big Beach) carries a swim caution today. Blue-green algae are not currently monitored at this water. Conditions can change quickly with wind, heat, and rain, so check the posted signs and look at the water before you get in.
- Does Oneloa Beach (Big Beach) have blue-green algae (cyanobacteria)?
- Blue-green algae are not currently monitored at Oneloa Beach (Big Beach). Watch for green, blue-green, or paint-like scum and avoid the water if you see it.
- Can dogs swim in Oneloa Beach (Big Beach)?
- No bloom is detected at Oneloa Beach (Big Beach) today, but dogs are much more vulnerable to blue-green algae than people, and blooms can form within hours. Always keep dogs away from water that looks green, scummy, or discolored, and rinse them off after swimming.
- How many Hawaii lakes and beaches have swim advisories today?
- Today, 0 Hawaii waters are under a swim advisory and 106 more warrant caution, out of 402 monitored waters SwimZone tracks in the state.
- How is Oneloa Beach (Big Beach)'s water quality measured?
- SwimZone builds this read from EPA CyAN satellite imagery for blue-green algae, official beach and fecal-bacteria advisories where a program monitors Oneloa Beach (Big Beach), and a recent-rainfall overlay, all refreshed daily. It was last updated July 19, 2026.