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Health warnings continue as blue-green algae flows down the Caloosahatchee

 A blue-green algae outbreak earlier this year at the public Davis Boat Ramp near Alva; other blooms have been seen down the Caloosahatchee River in the weeks since almost as far west as the Gulf of mexico
Lee County Environmental Lab
A blue-green algae outbreak earlier this year at the public Davis Boat Ramp near Alva; other blooms have been seen down the Caloosahatchee River in the weeks since almost as far west as the Gulf.

Hurricane Ian’s landfall on Sept. 28 last year helped foster a red-tide-a-thon that lasted eight months. Now there have been seven blue-green algae health advisories in Lee County alone since May

Red tide said goodbye to Fort Myers Beach in late April, and it hasn’t been seen again.

Blue-green algae showed up at Fort Myers Shores a month later, and it won’t go away.

Since then, there have been no less than seven blue-green algae health advisories in Lee County and one in Cape Coral warning of tainted water at Jaycee Park. One after another after another.


Each warning has been for an area further down the Caloosahatchee River, not as a river-full mass but as spotty mats that get caught in canals and stew, or move downriver with the flow.

The fear is that this year’s blue-green algae outbreak will both rival the nastiness of the ones in 2016 and 2018 and signal that the harmful algae bloom will become an unwelcome summertime fixture in Southwest Florida.

“We cannot allow it to be the new normal,” said Gil Smart, director of the clean-water nonprofit VoteWater based in Stuart. “We shouldn’t accept this given the health hazards, given the hazards to marine life, given what this can do to local economies, local communities. We can’t accept it.”

Blooming ocean

Ian’s landfall on Sept. 28 last year helped foster a red tide-a-thon that lasted eight months.

Red tide prefers saltwater; blue-green algae prefer freshwater. The former prefers winters; the latter prefer summers. Both will adapt, however, and ever since Ian we’ve been dealing with one sort of stink or the other.


The Florida Department of Health in Lee County first issued a countywide, no-swim advisory for all public beaches and swimming pools due to the possible increase of waterborne illnesses and debris washed in by the Category 4 storm just over a week after Ian hit.

“Avoid contact with contaminated water,” the agency’s atypically straightforward release read. “(We’re) advising the public not to enter the water due to the possible increase of waterborne illnesses. The water quality has been affected by Hurricane Ian and at this time, swimming is not recommended.”

The agency’s first health advisory due to red tide was on Nov. 18, for the spot where Ian’s eye made landfall: Boca Grande to the north and Captiva Island to the south. Another was issued an average of every two weeks until late April.


Thousands of dead fish – big dead fish – littered the beaches, stank for a while, got cleaned up, then thousands more washed ashore.

That acrid odor that wafts ashore with a strong red tide sent those without tolerance for noxious floating stimuli in their throats off the beach, back to their cars, and some to the hospital. The water turned red.

Offshore upwelling out in the Gulf of Mexico brought the red tide organism to the surface and then currents and winds drove it nearshore.

But the real magic happened when the mass tonnage of nutrients from fertilizers, animal waste and flooded septic systems washed back into the coastal waters with the stormwater runoff from Ian and collided with the red tide organism nearshore. The pollutants “fed” bloom after bloom, which scientists have discovered can make them grow larger and last longer than they might otherwise.

During those months, health agencies from Collier to Pinellas counties were issuing the same red tide advisories, collectively, dozens of times.


The red tide bell stopped ringing in Lee County on April 21. One month and a few days later, the blue-green algae drum started beating.

‘A wake-up call’

A large blue-green algae outbreak on Lake Okeechobee, which is polluted with nutrients like nitrogen and phosphorus, may have helped start the progression of blue-green algae mats and the subsequent health alerts as the river now begins where the western edge of the lake ends. Releases from the lake have slowed since June 1.

However, billions of gallons of the polluted water filled with blue-green algae had been released from the lake in previous months and now, mixed with blue-green algae from the greater Caloosahatchee watershed, the bloom is one and appears to be headed all the way to the Gulf of Mexico.


The cyanobacteria that comprise blue-green algae spread down the river in 2016 and 2018 and led to huge blooms during those summers that riverfront residents and water quality managers worry may become that new normal mentioned by Smart, of VoteWater.

“This should be a wake-up call,” he said. “We’ve got too many nutrients in the water.

“We have to deal with it. We’ve got to change that new normal.”

Environmental reporting for WGCU is funded in part by VoLo Foundation, a non-profit with a mission to accelerate change and global impact by supporting science-based climate solutions, enhancing education, and improving health. 

Copyright 2023 WGCU. To see more, visit WGCU.

Tom Bayles