How Lake Okeechobee contributes to red tide

While red tide invades our shoreline, there’s a lot of debate over how Lake Okeechobee contributes to the outbreak.

A lot of fingers are pointing to Lake Okeechobee for the most recent outbreak. It began in the month after Hurricane Ian. Researchers are evaluating whether we are headed for an environmental storm.

“The research that our lab has done in collaboration with UF has shown that the nitrogen from Lake Okeechobee is combining with other natural factors that cause red tide bloom to increase the initiation and intensity of the red tide blooms,” said Leah Reidenbach, an Sanibel Captiva Conservation Foundation research and policy associate.

Reidenbach points out that what we are experiencing now, five months after Ian, is similar to what happened after Irma in 2018.

Before Irma and Ian, Lake Okeechobee levels were low, then rose quickly after the storms.

“And the strategy after Irma was to release the water from the lake as soon as possible, as much as they could. So we were completely inundated with flows after Hurricane Irma. And that’s what was thought to contribute to the red tide blooms of 2018 that made them so intense and so long,” Reidenbach said.

After Ian, there was a different strategy: release for only six weeks compared to those four long months after Irma. “And the total volume of water that’s been released from the lake this year is 2.75 times less than it was after Irma,” said Reidenbach.

FGCU Professor Mike Parsons says Lake O is just one piece of the red tide puzzle.

“I also looked at nutrient levels in Lake Okeechobee, and the nutrient levels are not as high right now as they were in 2018. So it’s not as bad in terms of flow and nutrients as it was in 2018. But we know, and really had some huge impacts with the storm surge. And the red tide is a little worse right now, not a lot worse, but just a little worse.”

Those nutrients didn’t just come from the lake. They came from the water runoff into the rivers, ponds, and the Gulf.

Over the last five months, we’ve seen the red tide map light up, dead fish washing on shore, and ed tide health advisories unmoved, but are these signs we’re going to see another 2018?

“So when you first asked me that question, I went back, and I looked at the red tide maps that FWC produces. And we’re tracking more red tide now versus February of 2018,” said Parsons.

This red tide is more intense now than this time in the past, but 2018’s red tide had a twist.

“It started to decrease a bit in April and May, and then it really came back with a vengeance in June and July. And the thought at the time, or subsequently, was that a second red tide moved in,” Parsons said.

A second red tide, comething we can’t predict and hope we don’t see. The next thing Parsons looked at was Lake Okeechobee. A long debated piece of the red tide puzzle

“The discharges the inputs from Lake O definitely can feed red tide, and so they could make it worse. But with all of the other potential nutrient sources around, it’s not the only part of the equation.”

After both Irma and Ian, we received water from Lake O through the Caloosahatchee, but the Army Corps of Engineers released it differently.

“And there was about twice as much water coming through S79 in 2018 versus now. So we’re half of the water flow now versus 2018,” said Parsons.

He says the nutrient levels in Lake O are lower now than back then, which is a good thing. “So, you know, it’s, if I place a bet, I would say that it’s tracking differently. And I would hope that it would end up decreasing. But if a second red tide comes in, like we think happened in 2018, you know, all bets are off in that case.”