As the weather heats up, the Florida Department of Environmental Protection and the South Florida Water Management District (SFWMD) increase water sampling for cyanobacteria (also called blue-green algae) and toxins.
For the week of April 30 to May 6, 2021, there were 51 FDEP site visits in Florida, with 51 samples collected. Algal bloom conditions were observed by the samplers at 42 of the sites.
The most recent satellite imagery reviewed by FDEP for Lake Okeechobee showed low to moderate bloom potential along the shoreline of Lake Okeechobee, with the heaviest accumulation along the southeastern shoreline. No bloom potential was observed in visible portions of the Caloosahatchee and St. Lucie river and estuary systems.
On May 3, SFWMD staff collected samples at Moore Haven Lock on the lake side and the river side, and at the Port Mayaca Lock. All three samples were dominated by Microcystis aeruginosa. One of the Moore Haven Lock samples had trace levels of micrcystin at 0.52 parts per billion (ppb). The other sample had no detectable microcystin. The Port Mayaca Lock test showed 16 ppb of microcystins, a significant reduction in toxins from the previous week.
On May 3,FDEP staff collected samples inside and outside the Pahokee marina. Both samples were dominated by Microcystis aeruginosa. The sample taken inside the marina had microcystin levels of 1.2 ppb. The sample taken in the lake outside the marina had no detectable toxins.
The World Health Organization considers microcystin levels about 1 ppb to be unsafe to drink, and levels about 8 ppb to be unsafe for recreation contact (such as swimming.)
Of the 28 species of cyanobacteria documented in the Lake Okeechobee Waterway, about 25% are capable of producing toxins. Cyanobacteria capable of producing toxins do not always do so.
May 4 and May 5, SFWMD staff collected samples from Lake Okeechobee at the 28 stations. Cyanotoxin results are included in parentheses following each station name:
• KISSRO.0 (trace, 0.29 ppb);
• LZ2 (trace, 0.26 ppb);
• NES191 (1.3 ppb);
• L001 (trace, 0.74 ppb);
• NES135 (5.78 ppb);
On May 4, Lee County staff collected a sample from the Caloosahatchee River – Davis Boat Ramp. The sample was dominated by Microcystis aeruginosa and had no cyanotoxins detected.
On May 4, FDEP staff collected a sample from Lake Okeechobee at the Clewiston Boat Ramp. The sample was dominated by Microcystis aeruginosa and had 6.6 ppb microcystins detected.