Low algae toxin found in Lake Okeechobee
Levels not seen as risk to health; algae outbreak like 2016 called unlikely.
Samples of recently spotted blue-green algae in and around Lake Okeechobee tested positive for minuscule amounts of toxins this week, but there is no evidence that an algae outbreak similar to 2016 is imminent.
Two areas tested Monday at the Port Mayaca Lock and Dam and Canal Point had microcystin toxin levels far below what the World Health Organization considers hazardous. Both samples had less than 1 part per billion of microcystin toxin, according to the Florida Department of Environmental Protection.
Anything less than 10 parts per billion is not considered a health concern.
The results were released Thursday as South Florida water managers tried to assuage anxiety over algae sightings that followed the Army Corps’ action last week to begin Lake Okeechobee discharges into the St. Lucie Estuary. Discharges into the Caloosahatchee River west of the lake had been ongoing but were increased last week because of high water lev-
els from record-breaking May rains.
The harmful freshwater releases into the brackish estuaries are necessary to relieve pressure on the Herbert Hoover Dike, which protects Glades area communities from flooding. But they dilute the salinity levels needed for sea grasses and oyster beds to survive in the estuaries and add to algae-loving nutrient loads.
“I don’t have a crystal ball, and it’s really frustrating and challenging because you really can’t predict what is going to trigger a bloom,” said Terrie Bates, director of water resources for the district. “We just want to remind folks that algae blooms are natural. You can have bloom events that aren’t toxic.”
Bates spoke during a meet- ing of the South Florida Water Management District’s Water Resources Analysis Coalition on Thursday. She said conditions today are different than they were in 2016 when mats of green algae oozed through Treasure Coast waterways and closed beaches during the July Fourth holiday week- end.
In 2016, water had been flushing into the St. Lucie Estuary from Lake Okeechobee for five months by the time summer arrived with the longer days and warmer temperatures that algae thrive on. There was also a widespread algae bloom visible from satellite on the lake in 2016 that isn’t there today.
Blue-green algae are actu- ally cyanobacteria that produce a toxin to avoid getting eaten by zooplankton. The toxins can cause health prob- lems such as skin rashes and trouble breathing. Cyanobacteria can also get so abun- dant that when they die their decomposition can remove oxygen from the water and kill fish.
This year, the St. Lucie Estuary is especially vulnerable after a wet May doused it with local watershed runoff, creating a system that was nearly all freshwater before Lake Okeechobee discharges began, Bates said.
“We’ve been at this for so long, and we’re just not getting anywhere,” said H.M. Ridgely, a Martin County resident the water and resources member coali- of tion. “I’m tired of Martin
County people just screaming, ‘Lake Okeechobee.’ Yes, it’s a problem, but it’s not the only problem.”
A peer-reviewed study by a Florida Atlantic University scientist found that algae in lake discharges grow expo- nentially upon reaching the St. Lucie River because of heavy nitrogen levels specific to septic tanks.
of professor Branch Brian the study Oceanographic LaPointe, at and FAU’s lead a research Harbor author Institute, able to said trace the the study nitrogen’s was source not to fertilizer — long blamed for the growth — but to human sources.
“Everyone wants to blame this on the farms, and there is a lot of denial about the wastewater problem,”
LaPointe interview. said “People in a overlook January the role of population growth on the Indian River Lagoon, and a lot of that growth has relied on septic tanks.”
district National The water is Oceanic partnering management and with Atmo- the spheric Administration to monitor Lake Okeechobee for algae through its Center for Ocean Science. A satellite image is taken every other day that shows the extent of algae on the lake.
“In 2016, there was a well developed bloom in mid-May, and by this time it was quite large,” said Rick Stumpf, an oceanographer in the Center for Ocean Science. “What there is for a bloom now is really small.” Still, the state is trying to stay ahead of the situation, including looking for companies that can clean up algae if a bloom similar to that of 2016 appears. by have “We’ve vendors the answer,” been who bombarded say said they William Kennedy, an ecosystem project administrator with the Florida DEP. “But then we see their proposals, and we have to say, ‘No, you can’t put bleach in the water; no, you can’t spray it with copper.’ We can’t just let people disperse a bunch of chemicals.” If you haven’t yet, join Kim on Facebook, Instagram and Twitter.