Dense blue-green algal mats clump up at the gates of Port Mayaca on May 4, 2023, in Martin County. Photo by Leah Voss

It shouldn’t be normal that Floridians fear the threat of toxic algae in the summer months, just as we nervously watch for the approach of hurricanes — but recent, repeated history has given us good reason to be wary.

Water managers raised the alarm earlier this year, predicting an intense summer algae bloom on Lake Okeechobee due to heavy rainfall from Hurricane Ian that caused the lake to rise, delivering pollution-loaded runoff from the surrounding areas and killing submerged aquatic vegetation. 

Last week we saw signs that this unfortunate prediction may come to pass, when a dense bloom of bright green algae was spotted just inside the floodgates at Port Mayaca on the east side of Lake Okeechobee. A daily report generated by the Florida Department of Environmental Protection placed the bloom index identified at Port Mayaca at a 12 — the highest rating — indicating a high-severity bloom larger than a football field. Microcystin toxin levels were 2.8 parts per billion on May 1, below the Environmental Protection Agency’s “too toxic to touch” limit of 8 parts per billion, but a concerning harbinger of what may come this summer.

Graph credit: FDEP South Florida System Update USACE BGA Report: May 4, 2023

Thankfully, the gates at Port Mayaca leading to the St. Lucie River were closed at the time the bloom was observed, but with temperatures heating up and the June 1 start of rainy season just around the corner, it’s alarming to see this level of algae activity. 

Friends of the Everglades will continue to encourage the Army Corps of Engineers to consider the danger of harmful algal blooms when releasing water from the lake. With this public health threat looming, it’s imperative to assess conditions before water-management decisions are made that could threaten the downstream communities on the east and west coasts.