USACE to stop Lake O releases

Posted 3/29/24

Lake Okeechobee will start the wet season around 14.5 feet (above sea level) according to estimates shared by Col. James Booth ...

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USACE to stop Lake O releases


Lake Okeechobee will start the wet season around 14.5 feet (above sea level) according to estimates shared by Col. James Booth, commander of the U.S. Army Corps of Engineers (USACE) Jacksonville District in a March 29 media call.

Booth said during the 2023-2024 wet season, the El Nino weather pattern brought above average rainfall. In a normal dry season, Lake Okeechobee drops about 3 feet due to evapotranspiration (a combination of evaporation and plant transpiration). This past winter, the lake level did not drop and even started to rise.

According to RECOVER, the lake’s normal ecological envelope ranges from 12 feet at the end of the dry season to 15 feet at the end of the wet season. The lake’s recovery envelope uses a low of 11.5 to 12.5 and a high of 14.5 to 15.5. RECOVER (REstoration COordination & VERification) is a multi-agency team of scientists, modelers, planners and resource specialists who organize and apply scientific and technical information in ways that are essential in supporting the objectives of the Comprehensive Everglades Restoration Plan (CERP).

At 15.5 feet, the lake’s marshes are inundated with water. As the lake level rises, the water stacks up against the side of the dike. High water levels can damage or destroy the vegetation, which is the lake’s natural filter system. Due to high water levels left in the aftermath of Hurricane Ian in 2022, the lake’s vegetation has been suffering for years. The lowest lake level in 2023 was 13.7 feet.

On Feb. 17, when the lake level was around 16 feet, USACE began high level releases of 4,000 cubic feet per second (cfs) to the Caloosahatchee River and 1,800 cfs to the St. Lucie River as well as 500 cfs to the Lake Worth Lagoon. USACE also released as much water south as the system capacity allowed. Heavy rainfall south of Lake Okeechobee meant less water was needed for irrigation and water supply. Rainfall south of the lake also took up capacity in the stormwater treatment areas (STAs) and Water Conservation Areas (WCAs).

Over a six-week period the high releases, combined with evapotranspiration, dropped the lake about 10 inches, Savannah Lacy, USACE hydraulic engineer.

Booth said while he acknowledges the negative environmental impacts the freshwater releases have on the coastal estuaries, “I think it was the right choice.” He said they needed to lower the lake to have capacity in the lake to accept water in from the north in the wet season.

USACE will pause lake releases east and west for a two-week period starting on Saturday, March 30.  Booth said he will announce a decision about future releases on April 5.

“We’re in a transition from the El Nino pattern,” Booth said. The wetter than normal dry season could be followed by a hotter than normal wet season.

He said high temperatures in the Atlantic Ocean could mean a more active hurricane season.

Halting freshwater releases will improve salinity levels in the coastal estuaries, said Booth. He said over the past two weeks, the Caloosahatchee River flow included about 2,000 cfs from local basin runoff. However, if there is no rain in the local basin, they will release lake water to maintain the optimal salinity levels in the Caloosahatchee estuary. The South Florida Water Management District has set the minimum flow level at the W.P. Franklin Lock at 457 cfs.

Booth said future releases will depend on conditions. A big storm can raise Lake O by several feet. He said USACE will prioritize the integrity of the Herbert Hoover Dike and flood protection for south Florida residents.

Booth said the U.S. Army Engineer Research and Development Center (ERDC) has released a grant to study algal treatment methods. In addition, the National Oceanic and Atmospheric Administration (NOAA) will bring out a new algal bloom predictive tool this summer “which will look out three to five days to understand where there is a higher chance for an algal bloom to occur,” Booth continued.

Lake Okeechobee, lake level