Releases from Lake Okeechobee to the Caloosahatchee River will be slightly lower than anticipated in February.
On Jan. 28, Col. Andrew Kelly, Jacksonville District Commander for the U.S. Army Corps of Engineers, indicated the corps planned to start releasing 2,000 cubic feet per second (cfs) to the Caloosahatchee on Feb. 6. Currently the flow, measured at the Franklin Lock, is 1,000 cfs.
On Feb. 4, Kelly lowered that target to 1,500 cfs to the Caloosahatchee.
The Caloosahatchee River needs freshwater from from the lake during the dry season to maintain the salinity balance in the estuaries. Flows below 450 cfs (measured at the Franklin Lock) are considered harmful as the salinity levels in the estuaries are too high. Flows higher than 2,800 cfs are also considered harmful because the salinity levels drop too low. The ideal beneficial freshwater flow at the Franklin Lock advocated by estuary scientists is around 1,000 cfs, but the ideal salinity level varies for different parts of the estuaries.
Rainfall could result in higher releases than the 1,500 cfs target to the Caloosahatchee River, due to local basin runoff. The Franklin Lock is 43.4 miles from the Moore Haven Lock, where water from the lake enters the river.
Col. Kelly said they hope to have potential to move more water from the lake south, as water levels in the Water Conservation Areas recede.
No releases are planned to the St. Lucie River at Port Mayaca. Rainfall could result in water released from the St. Lucie Canal at the St. Lucie Lock, but this would be basin runoff, not lake water.
These releases will be re-evaluated regularly.
The releases are part of a September 2020 approved planned deviation from the 2008 Lake Okeechobee Regulation Schedule to reduce the risk of exacerbating potential health concerns associated with algal blooms in Lake Okeechobee, the St. Lucie, and Caloosahatchee estuaries during the summer.
“While our original target was in-line with recommended RECOVER ecological envelope for the Caloosahatchee, over the past week we listened to partners, stakeholders, and scientists who urged caution given current conditions, especially on the coast,” said Kelly.
“We intend to maintain an aggressive approach – utilizing the harmful algal bloom deviation approved in September – as we remained concerned about the potential high lake levels entering hurricane season and the elevated potential for high volume releases as a result. We will actively monitor the conditions and adjust accordingly including the potential need to release water to the St Lucy, potentially increase releases west, and as always maximize releases south," he said.
On Feb. 4, the lake stage was s at 15.42 feet, which is still 2.5 feet higher than it was one year ago, and 2.7 feet higher than it was two years ago.
“With the lake coming down, we also passed a milestone point that allowed us to stop the increased dam safety inspections we began in October last year,” Kelly said. “Our teams in the South Florida Operations Office have been on the southern portion of Herbert Hoover Dike every two weeks since the lake went over 15.5 feet. In that time, we are happy to report we found no distress or increased seepage and did not need to initiate any flood fighting efforts beyond the increased inspections.”
The additional flow of 500 cfs will not make a significant difference in the level of the big lake. One inch on Lake Okeechobee is about 12 billion gallons of water. A flow of 500 cfs is equal to 323 million gallons per day or 2.2 billion gallons per week. That means it would take more than five weeks for a flow of 500 cfs to lower the lake by one inch.
Kelly indicated the plans may change as the wet season nears. There is still concern the lake could be above 14 feet on June 1, the start of the wet season. Since, the current Lake Okeechobee Regulation Schedule (LORS) went into effect in 2008, every year in which the lake was about 14 feet on June 1, the lake level has risen high enough in the summer months to require freshwater releases to the coastal estuaries.