Algae bloom conditions intensify in Lake O; Cyanobacteria sampled in Caloosahatchee River has low levels of toxins; Caloosahatchee flow is basin runoff

OKEECHOBEE — Hot temperatures over the past week resulted in an increase in the cyanobacteria and algae in Lake Okeechobee, according to the Florida Department of Environmental Protection.

The NOAA imagery from June 20 shows a high potential for algae and cyanobacteria blooms in the center of the lake. The imagery does not show actual blooms. It is created with a computer model based on data collected by the satellite. Areas in red have the highest potential for a visible bloom of cyanobacteria.


Satellite imagery from the National Oceanic and Atmospheric Administration (NOAA) shows potential for algae blooms in about 75 percent of the big lake. Bloom potential does not always mean there is a visible bloom in the area; however, fishermen have reported algal blooms on the big lake this summer.

Cyanobacteria reported in Caloosahatchee River
Lee County staff observed algae blooms at the Davis Boat Ramp on the Caloosahatchee River. Since the rains started, the corps cut off flow from the lake to the Caloosahatchee. According to the U.S. Army Corps of Engineers report, 96% of the flow at the Franklin Lock last week was from local basin runoff.


On June 15, South Florida Water Management District staff collected samples at Lake Okeechobee-S308C structure (lakeside) at Port Mayaca and on the C-43 Canal-S77 structure (upstream) at Moore Haven. Neither sample had a dominant algal taxon. Cyanotoxins were not detected in either sample.


On June 16, Lee County staff collected a sample from the Caloosahatchee River-Davis Boat Ramp. The sample was dominated by the cyanobacteria Microcystis aeruginosa. There were 4.3 parts per billion of total microcystin detected in the sample. (The EPA considers level below 8 parts per billion to be safe for human recreational interaction.)

Algae and cyanobacteria (known as blue green algae) are always present in freshwater lakes, streams, rivers and waterways as part of the natural ecosystem. Excess nutrient load combined with little water movement and high temperatures can result in rapid reproduction of the algae and/or cyanobacteria into a “bloom.” Most “blooms” are a mixture of species of algae and cyanobacteria. Of the 28 species of cyanobacteria documented by the U.S. Geological Survey in the Lake Okeechobee Waterway, about 25 percent are capable of producing toxins. Even those capable of producing toxins do not always do so. The Lake Okeechobee Waterway includes the Caloosahatchee River, Lake Okeechobee, the St. Lucie Canal and the St. Lucie River.

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