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Expect 'a summer of slime' on Lake Okeechobee; Caloosahatchee River

Lake Okeechobee near Clewiston is seen from a National Oceanic and Atmospheric Administration satellite specially equipped to see harmful algae blooms, which took this image of the massive 2018 blue-green algae outbreak, and conditions are right for another, perhaps bigger, outbreak of the slimy green algae this summer
Lake Okeechobee near Clewiston is seen from a National Oceanic and Atmospheric Administration satellite specially equipped to see harmful algae blooms, which took this image of the massive 2018 blue-green algae outbreak, and conditions are right for another, perhaps bigger, outbreak of the slimy green algae this summer

The large outbreak of blue-green algae is expected this summer on Lake Okeechobee after red tide has been rampant in part due to nutrient pollution from Hurricane Ian

The surface of Lake Okeechobee is expected to turn the wrong color this summer as all the elements for a huge outbreak of blue-green algae are in place.

Warm water, ample sunlight, and calm weather is what blue-green algae needs to flourish, and those conditions are present in South Florida every summer. But the key ingredient for any harmful algae bloom in the lake - nutrients - are usually stuck down in the muck.

But what is “usual” has changed in South Florida since Hurricane Ian. Stronger tropical cyclones caused by warming ocean waters due to rising temperatures worldwide are tilting environmental conditions in favor of worsening natural disasters, and that includes harmful algae blooms such as blue-green algae and red tide.

Last fall’s Category 4 storm whipped up waves on Lake Okeechobee and churned up the bottom, where accumulated layers of phosphorus and nitrogen that washed off nearby industrial-scale farms and settled long ago were stirred up into the water column.

“What you have is a perfect storm of possibility for blue-green algae blooms that are going to feed off those nutrients,” said Gil Smart, the director of VoteWater, a nonprofit working to stop algae-laden discharges from Lake Okeechobee. “We've seen both federal and state water managers sound the alarm about the potential for this.”

The Army Corps of Engineers decides when to let water out of Lake Okeechobee, both to protect the integrity of the Herbert Hoover Dike that rings the shoreline and to try and restore something close to the water flow nature intended. The lake’s release valves are the Caloosahatchee River to the west and to the St. Lucie River to the east.

If the water in the lake has got to go, and there is an active algae outbreak on the surface, the harmful bacteria goes with it as happened last time the lake was covered with putrid blue-green algae in 2018.

“It absolutely clogged the St. Lucie River: It was grotesque. It smelled. It caused all sorts of problems. Businesses closed. Fish and wildlife died,” VoteWater’s Smart said. “We cannot afford another summer of slime.”

The hurricane effect

The similarities between Hurricane Ian in 2022 and Category 3 Hurricane Irma in 2017 are driving both anxiety over harmful algal blooms like red tide that have already happened, and anticipation of a massive blue-green algae outbreak on Lake Okeechobee this summer.

Hurricanes Ian and Irma share far more than their first letter. Each made landfall in Southwest Florida. As a major hurricane. In September. And each hurricane’s strong winds riled up Lake Okeechobee. Both were followed by another, lesser but still powerful water-churning hurricane, Maria and Nicole, respectively.

That major blue-green algae outbreak on the big lake in 2018 that Smart described, which spread throughout both the St. Lucie and Caloosahatchee estuaries, occurred the summer after Hurricane Irma.

Judy Baxter via Flickr

Irma and Ian have already preceded long stretches of red tide off Southwest Florida, which are thought to be made worse by the huge amounts of nutrient-rich stormwater washed off the land and into coastal waters that “feed” red tide blooms already underway.

A University of Florida study reported the direct impacts of the post-Irma red tide “event” lasting from after the storm in 2017 until early 2019 was more than $184 million, with indirect costs possibly reaching three times that.

Irma’s direct economic losses are thought to be least $8 million in Lee County alone.

Relentless red tides have been blooming off Southwest Florida beaches since the week after Hurricane Ian made landfall on September 28, 2022, at a barrier island off Lee County.

More than five months later the harmful algae blooms are still growing in number and severity.

This week the red tide organism, Karenia brevis, was found in 123 water quality samples offshore of Southwest Florida, more than any week so far in the region. A bloom strong enough to turn the water a visible red was detected in 75 of the samples, including seven off Manatee County, 27 offshore of Sarasota County, seven off Charlotte County, 22 offshore Lee County, nine off of Collier County, and one offshore of Monroe County.

Dead fish suspected to be smothered by red tide washed up on all of the same shorelines, and beachgoers suffered from coughing, watery eyes, runny noses, and other respiratory irritation.

The economic impacts of a red tide outbreak after direct losses, the UF researchers said, are quickly speculative.

There is not enough data to gauge the damage to the economy from the blue-green algae outbreak in the Caloosahatchee River in 2017, but the consensus that the economic impact on the tourism industry in Southwest Florida was significant.

For reference, a blue-green algae outbreak in 2016 in Florida's Treasure Coast cost the local economy $237 million in lost sales and 3,000 jobs, according to a study by National Oceanic and Atmospheric Administration.

Blue-green fears

Hurricane Ian was bigger, more powerful, moved slower, and hung together far longer Hurricane Irma.

NOAA says Hurricane Irma caused about $60 billion in damages across Florida, making one of the costliest hurricanes in American history.

The cost of Hurricane Ian’s damage is at $113 billion and still growing, double Irma’s destruction and placing Ian as the most devastating hurricane to ever strike the Sunshine State. Ian was far more damaging than Miami’s Hurricane Andrew in 1992, and Hurricane Charley, which made landfall at the same spot as Ian, in 2004.

Throughout those years Lake Okeechobee was becoming more polluted with nutrient runoff associated with fertilizers, whether from the nearby farms or homeowners from Orlando south who spread too much on their lawns.

Stormwater runoff from Central Florida moves south along the Kissimmee River and its watershed, funneling it into the Big Lake. Estimates have enough nitrogen and phosphorous in that watershed to sustain high levels of nutrients flowing into Okeechobee for 50 years, even if farming stopped right now.

The Florida Department of Environmental Protection and the South Florida Water Management District drew nearly two dozen water quality samples late last week and tested them for components of blue-green algae. Lake Okeechobee’s waters were clear.

A NOAA satellite pointed at Lake Okeechobee that can detect harmful algae blooms found nothing to note, either.

Summer begins on June 21.

The Army Corps of Engineers decides when and how much water to release into the Caloosahatchee or St. Lucie rivers.

About 1.9 billion gallons of water per day has been released from Lake Okeechobee into the Caloosahatchee River on average this year. The floodgates remain open.

Col. James Booth is the Army Corps commander in the region that includes Florida.

“We expect an increased risk of algal blooms next summer due to the hurricanes,” Col. Booth said. “During the height of hurricane emergency response efforts, our decisions were easy to reduce immediate impacts.

“Now, the question of how to manage all the water in Lake Okeechobee is upon us, and the solution is not an easy one.”

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. 

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Tom Bayles