LAKE OKEECHOBEE – Toxin levels have dropped significantly in the algal bloom in the water control structure near Canal Point.

According to the Florida Department of Environmental Protection (FDEP), on July 16, a water sample from a visible bloom in the S352 water control structure had a toxin level of 53 parts per billion (ppb).

The Environmental Protection Agency (EPA) considers levels above 8 ppb to be unsafe for human recreation contact (swimming) and levels above 1.0 ppb to be unsafe for drinking water.  A sample taken July 30 showed a barely detectable toxin level of 0.16 ppb.

Cyanobacteria – commonly called blue-green algae – are present in all freshwater. Most of the time these microscopic organisms are not visible to the human eye. Under certain conditions – hot weather, available phosphorous and nitrogen in the water and lack of water movement – cyanobacteria can reproduce rapidly into a visible “bloom.” Such as bloom usually dies off when the available nutrients are exhausted or dissipate when water flow resumes. There has been little to no flow through the S352 water control structure for months, as the lake level is in the lower management band and rainfall south of the Big O has been sufficient for water supply there.

Cyanobacteria and algae are part of the natural ecosystem and found in all freshwater (that is not sterile). Of the 28 species of cyanobacteria documented by the U.S. Geological Survey in the Lake Okeechobee Waterway, about 25% are capable of producing toxins. Florida Atlantic University studies have documented the connection between high levels of dissolved inorganic nitrogen in the water and production of toxins by cyanobacteria.  

FDEP samples water at sites where algal blooms are reported. In addition, the South Florida Water Management District takes water samples from 34 locations on Lake Okeechobee every two weeks during the wet season.

July 25-31, FDEP sampling detected trace levels of toxins in Lake Oliva in Highlands County, Doctors Lake in Clay County and Lake Thonotosassa in Hillsborough County.

A lakeside sample at the Port Mayaca Lock on Lake Okeechobee had a trace toxin level of 0.53 ppb.

July 28-30, St. Johns River Water Management District samplings found trace levels toxins in Lake George, the St. Johns River south of Hwy 17 and Dead Lake.

According to FDEP all the water samples taken for the week had toxin levels below the safety standard for drinking water.

NOTE: Okeechobee Utility Authority uses Lake Okeechobee as its primary water source. Part of the OUA water treatment process destroys cynaobacteria toxins, using the method recognized by EPA.