Beach · St. Thomas Island County · VI
Is SAPPHIRE BEACH safe to swim?
No advisory or algae bloom reported for this water today.
Updated July 19, 2026 · U.S. Virgin Islands beach program (EPA BEACON)
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Know before you get in at SAPPHIRE BEACH.
Get an alert the day a bacteria or algae advisory goes up.
What's in the water at SAPPHIRE BEACH right now
As of July 19, 2026, SAPPHIRE BEACH in St. Thomas Island County, U.S. Virgin Islands is clear to swim. 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 0.0 in, which can wash bacteria and nutrients into the water.
Blue-green algae at SAPPHIRE BEACH
SAPPHIRE BEACH is a lake in St. Thomas Island County, U.S. Virgin Islands. 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 SAPPHIRE BEACH
- Is it safe to swim in SAPPHIRE BEACH right now?
- SAPPHIRE BEACH is clear to swim 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 SAPPHIRE BEACH have blue-green algae (cyanobacteria)?
- Blue-green algae are not currently monitored at SAPPHIRE BEACH. Watch for green, blue-green, or paint-like scum and avoid the water if you see it.
- Can dogs swim in SAPPHIRE BEACH?
- No bloom is detected at SAPPHIRE 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 U.S. Virgin Islands lakes and beaches have swim advisories today?
- Today, none of the 44 monitored U.S. Virgin Islands waters SwimZone tracks are under a swim advisory.
- How is SAPPHIRE 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 SAPPHIRE BEACH, and a recent-rainfall overlay, all refreshed daily. It was last updated July 19, 2026.