Summer heat brings increase in algae blooms

The summer heat continues to support algae blooms in Florida’s inland waters, Lt. Todd Polk, deputy commander of the U.S. Army Corps of Engineers Jacksonville District explained in a July 21 media briefing.

“With inland lakes and streams, algae should always be a concern,” he said.

“It’s not just Lake Okeechobee, he said. Nutrients in the water in local basin runoff feed algal blooms all over the state.

Cyanobacteria – commonly called blue-green algae – are part of the natural ecosystem. These microscopic organisms are always present in canals, lakes and streams. Under certain conditions – hot weather, little water movement and sufficient nitrogen and phosphorus in the water – cyanobacteria can reproduce rapidly into a visible bloom. About 25% of the 28 species of cyanobacteria documented by the U.S. Geological Survey in the Lake Okeechobee Waterway are capable of producing toxins. However, even species of cyanobacteria capable of producing do not always do so.

Blue-green algal blooms in the Caloosahatchee River and Lake Okeechobee have been in the news this summer. Polk said the blooms in the Caloosahatchee River are fed primarily from the nutrients in local basin runoff. Very little lake water has been released to the river since the start of the wet season in May. The target flow for the Caloosahatchee River is set at the beneficial flow level of 2,000 cubic feet per second (cfs), as measured at the Franklin Lock, more than 40 miles from Lake Okeechobee. The estuary needs freshwater flow to prevent salinity levels from rising too high. No lake water is released unless the average flow drops below the 2,000 cfs target. For the seven-day period ending July 21, flow at the Franklin Lock averaged 2,834 with less than 3% of that flow coming from Lake Okeechobee. SFWMD records show the nutrient load in the Caloosahatchee basin runoff is as high or higher than the nutrient load in Lake Okeechobee water.

Lake Okeechobee water is only released to the river on days there is not sufficient rainfall to meet the target. On July 20, flow at the Franklin Lock averaged 4,100 cfs with no lake water released into the river at Moore Haven.

Most of the flow into Lake Okeechobee is coming from the Kissimmee River and the Istokpoga basin, Polk said.

Lake Okeechobee was “just a hair shy of 15 feet,” on July 21, Polk said.

USACE has no current plans to release any lake water to the St. Lucie Canal. Polk said flow through the St. Lucie Lock is local basin runoff.

The wet season has inundated the restored portion of the Kissimmee River. “The restored area of the Kissimmee River is full and performing as expected,” said Polk. The flood plain is “definitely full of water.”

Polk said they have no immediate plans to change the lake release targets. “That doesn’t mean we’re out of the woods,” he added.

“One big storm can change everything,” he warned. Last year, runoff from Hurricane Ian pushed the lake level up 4 feet.

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