The Weather Channel:
Water samples collected on the St. Lucie River contain high levels of microcystin, a toxin that can make people sick. If ingested, water contaminated with the toxin can cause nausea, vomiting and, in severe cases, acute liver failure. Coming in direct contact with the algae can result in a rash.
(click here to continue reading Florida's Blue-Green Algae Bloom 10 Times Too Toxic to Touch, Testing Shows | The Weather Channel.)