Blue-green algae bloom at Bathtub Beach was slightly toxic, DEP tests show

Tyler Treadway | Treasure Coast Newspapers

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A blue-green algae bloom that prompted Martin County to close Bathtub Beach Aug. 22 was slightly toxic, according to the Florida Department of Environmental Protection.

The water contained the toxin microcystin at a level of 1.2 parts per billion. The World Health Organization considers water with up to 1 part per billion safe to drink.

On a second visit to the beach Monday, the DEP sampling crew found no algae.

All Martin County beaches were open for swimming Tuesday, according to the county's beach information hotline.

Bathtub Beach, one of the county's most popular tourism destinations, was closed to swimming late Aug. 21 and Aug. 22 because lifeguards reported a possible blue-green algae bloom just offshore.

More: Bathtub Beach closed because of blue-green algae

It reopened briefly, but all the county's beaches with lifeguards — Bathtub Beach, Stuart Beach, Jensen Beach and Hobe Sound Beach — were closed over the weekend when algae reappeared.

The algae can, but doesn't always, produce toxins. Microcystin, a common blue-green algae toxin, can cause nausea and vomiting if ingested and rash or hay fever symptoms if touched or inhaled. Drinking water with the toxins can cause long-term liver disease.

More: Blue-green algae FAQs

Lifeguards update beach conditions throughout the day at 772-320-3112.

Double red flags will fly at beach lifeguard stations whenever swimming is not allowed.

Beaches closed for swimming typically remain open for walking and shelling.

More: Blue-green algae blooms' effects on Treasure Coast dolphins, manatees, sea turtles unknown

Report algae sightings