'Toxic algae watch': Health department, advocates monitor Lake O, Caloosahatchee cyanobacteria

A boat prepares to head through the Franklin Locks on Monday, June 13, 2022. A caution alert sign has been recently placed at the Franklin Locks on the Caloosahatchee River. The sign alerts visitors that there may be blue green algae in these waters. Photographed just downstream of the locks.
Amy Bennett Williams
Fort Myers News-Press

A month into the summer rainy season, the signs have begun appearing at popular Southwest Florida waterways.

Sporting red or yellow tops depending on threat level, they warn would-be recreators about cyanobacteria, also called blue-green algae.

So far, Olga’s W.P. Franklin Lock has a health alert (the more serious of the two), while the Alva and Davis boat ramp in Fort Myers Shores have cautions.

Placed by the Florida Department of Health in Lee County, the signs don’t seem to be stemming the steady flow of boaters, Jet Skiers and anglers taking to the river, which flows from Lake Okeechobee to the Gulf of Mexico.  

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It’s too early to tell if this portends a difficult algae season, but scientists and advocates are watching carefully.

Beyond the human health risks linked to some algae toxins – rashes, gastrointestinal distress, liver cancer and neurodegenerative disease – are the hazards to wildlife and the region’s tourism-based economy.

2018 blooms still haunt

A health alert sign has been recently placed at the Franklin Locks on the Caloosahatchee River. The sign alerts visitors that there is blue green algae in these waters.  Photograph taken on Monday, June 13, 2022. The sign is shown upstream of the locks.

The wounds of 2018 are still fresh.

That year, a toxin-producing cyanobacteria began blooming on the big lake early in the rainy season. 

When water levels rose and threatened the earthen dike ringing the lake, water managers released flows into the Caloosahatchee River to relieve the pressure.

Blooms spread throughout the river, killing fish and wildlife, sickening some residents and hurting tourism and the real estate market, just as red tide, a saltwater alga was wreaking havoc in the river’s tidal estuary and in the Gulf of Mexico. 

It’s impossible to say whether such a disaster will happen again this year – or ever – but Barry Rosen is reasonably sure it won’t be anytime soon.

Rosen, a renowned algae-focused professor at Florida Gulf Coast University's Water School takes several factors into account when considering what the near future might hold, bloomwise.

“First of all,” he said, “what’s the likelihood that water’s going to be discharged from the lake into the Caloosahatchee? So you look at lake stage (level). Right now, it’s at just  over 13 feet – not very full at all. It’s where they want to be at the beginning of the hurricane season – that’s pretty good. Right now it’s low (and) unless we get successive big rainfalls, it’s not going to go up into the point of discharge.”

Then Rosen examines satellite images, which currently don’t look alarming, he says.

Then he looks at the state’s blue-green algae dashboard and the daily snapshot provided by the  U.S. Army Corps of Engineers, the federal agency that manages the lake.

He also checks the U.S. Geological Survey site for nitrogen levels. “Nitrate plus nitrite (is) the fuel that these organisms need, and we know the watershed it the major contributor – the lake is not … so those values are low now.”

For the next week or so, he says things look clear, and overall, Rosen says, “My alert level is about five.”

'I don't think anybody knows'

Theresa Rivers fishes for mullet at the Franklin Locks on Monday, June 13, 2022. A caution alert sign has been recently placed at the Franklin Locks on the Caloosahatchee River. The sign alerts visitors that there may be blue green algae in these waters.  Photograph taken on Monday, June 13, 2022.

Some scientists and advocates are much more concerned than Rosen.

“I don’t think anybody knows (what will happen), but it certainly is a bit unsettling that the lake is higher than we like it to be going into the rainy season,” said Daniel Andrews, executive director of the nonprofit Captains for Clean Water.  Though he wishes the Corps had kept it lower, “It’s too late for that now. We’ve got a high lake and it’s raining,” he said, “all the more reason we need more water flowing south in the dry season – January through May. When you get to June and the rain starts, you lose that capacity.”

With a new regulatory plan likely coming online before the next rainy season, “we just need to get through this one year.”

The Army Corps of Engineers has, since 2008, worked to keep lake surface levels between 12.5 and 15.5 feet above sea level for flood protection and to provide water for urbanized areas, farming and the environment. 

As for the potential for red tide, Andrews points to a recent University of Florida study that links landscape runoff to the blooms that he hopes water managers heed.

“If there’s red tide levels present and we start dumping Lake O water out there, it’s going to make it worse. We haven’t had that concrete science in the past.  This year we do. And it further highlights why we need to reduce these discharges as much as possible,” he said.

Calusa Waterkeeper John Cassani points to the “massive” 160-square mile bloom on Lake O, which currently covers more than 20% of the lake’s surface “and will likely increase in distribution as we are still early in the wet season,” plus, the warming weather helps incubate blooms.

That’s seconded by James Evans, CEO of the nonprofit Sanibel-Captiva Conservation Foundation. “For the first time in a while, our weekly Caloosahatchee Conditions report shows we’re in the harmful flow envelope because of basin runoff – not the lake.”

A mother muscovy duck and her ducklings swim past a caution sign at the Franklin Lock on the Caloosahatchee River on Monday, June 13, 2022. The caution sign alerts visitors that there may be blue green algae in these waters.  This sign is placed on the downstream or West side of the locks.

That means that so much rainwater is flowing to the river from the surrounding landscape that it’s upsetting the salinity balance needed by some aquatic plants and animals.

The challenge: the river’s estuary needs some fresh water to stay healthy, but too much of the polluted, algae-tainted releases from the landscape and the lake can feed algae blooms, including, saltwater red tide. Caused by a marine microorganism, it can cause respiratory woes and headaches in humans, and sicken wildlife, sometimes leading to massive bird and fish kills.

And, Cassani says, because that runoff carries with it nitrogen and phosphorus, which act as algae fertilizers, “further (bloom) development would seem likely.”

Friends of the Everglades Executive Director Eve Samples says she and her advocate colleagues are “on toxic algae watch” now that the weather is warmer and less windy.

“We know when we have hot, still conditions on the lake, that’s when these blooms tend to explode,” Samples said. “We know we’re going to see a significant bloom at some point.”

In the meantime, she’s keeping an eye on tropical storm systems.

“We’re just watching to see what the next tropical system may bring and hoping it doesn’t raise lake levels dramatically in a manner that would require toxic discharges,  because until we fix this problem of using the estuaries as dumping grounds for toxic Lake Okeechobee water, this is the risk we’re going to live with every single summer.”

About cyanobacteria

What is it? Cyanobacteria, also called blue-green algae, are single-celled bacteria common in Florida freshwater. Blooms happen when rapid growth of algae leads to an accumulation that can discolor water and produce foul-smelling floating mats.

What causes blooms? Contributing factors include nutrients that fertilize the algae,  sunny days and warm, still water. Blooms can appear year-round but are more frequent in summer and fall.

Are they harmful? Some toxin-producing varieties can sicken humans, pets and wildlife.

Learn more: Visit floridahealth.gov/environmental-health/aquatic-toxins. Find current information about Florida’s water quality status and public health notifications for harmful algal blooms and beach conditions by visiting ProtectingFloridaTogether.gov. Protecting Florida Together is the state’s joint effort to provide statewide water quality information to prioritize environmental transparency and commitment to action.

What do I do if I see an algal bloom? The Florida Department of Environmental Protection collects and analyzes algal bloom samples. To report a bloom to DEP, call the toll-free hotline at 855-305-3903 or report online.

To report fish kills: Call the Florida Fish and Wildlife Research Institute at 1-800-636-0511.

Report symptoms if exposed: Call the Florida Poison Information Center at 1-800-222-1222 to speak to a poison specialist immediately.

For other health questions or concerns about blue-green algae blooms: Call the Florida Department of Health in Lee County at (239) 690-2100.

Sources: Florida Department of Health in Lee County, The News-Press research.