JACKSONVILLE — The U.S. Army Corps of Engineers will start reducing the outflows from Lake Okeechobee to the coastal estuaries on Saturday, Dec. 5.
Starting Saturday, the St. Lucie River will get a five-day pause of lake releases, and releases to the Calooshatchee River will be reduced by 25%.
“Today the lake is just a little over 16 feet,” said Col. Andrew Kelly on Thursday. “It’s still about 3 feet higher than it was this time last year.” Kelly said the wet season appears to be over. “Our releases now are more geared toward a forward-looking dry-season strategy which we will roll out in the next couple weeks,” he explained.
“We’ve got to get water off the lake — 16 feet is very high,” he said.
Beginning Dec. 5, USACE will begin the transition to dry season operations on Lake Okeechobee by implementing a seven-day release with a reduced average target flow for the Caloosahatchee Estuary of 3,000 cubic feet per second (cfs) as measured at the Moore Haven Lock & Dam (S-77). At the same time, the corps will implement a multi-week release pattern for the St. Lucie Estuary, starting with a five-day pause to allow for recovery of estuary health, followed by a seven-day average release of 1,500 cfs as measured at St. Lucie Lock & Dam (S-80) near Stuart.
Since Oct. 14, the target at Moore Haven has been 4,000 cfs. The target at St. Lucie Lock has been 1,800 cfs. Water from the lake enters the St. Lucie Canal at Port Mayaca, so the flow at the St. Lucie is a mixture of lake water and local basin runoff.
Kelly said they hope to cut the releases to the Caloosahatchee River down to 2,000 cfs the following week, and continue releases to the St. Lucie on a cycle with five days of no releases followed by seven days of 1,500 cfs.
“We will reduce the releases from Lake Okeechobee over the next month,” said Col. Andrew Kelly, commander of the Jacksonville District. “The 2020-2021 dry season has begun, and we will manage the lake in tandem with the needs and concerns of the people and ecosystems of South Florida.”
Additional runoff from rain in the local Caloosahatchee and St. Lucie basins could occasionally result in flows that exceed one or both targets. USACE lock operators will make real-time adjustments to spillways along the Caloosahatchee and the St. Lucie Canal to maintain canal levels.
Lake Okeechobee is currently at 16.02 feet above sea level. During the past week, lake levels receded by 0.18 feet, with a 0.19-foot drop in the past 30 days.
Since Oct. 14, based on the average flow data posted on the USACE website, about 28.742 billion gallons of water has flowed from the lake into the St. Lucie at Port Mayaca — which equals about 2.4 inches on Lake Okeechobee. Also since Oct. 14, about 102.87 billion gallons of water have flowed from the lake at Moore Haven into the Caloosahatchee River — about 8.57 inches on Lake Okeechobee. If the corps had not conducted the releases, the lake would be about 11 inches higher now than it was on Oct. 14.
Without the lake releases, “where we topped out would have been well over 17 feet,” said Kelly. He stated although all of the dam safety analyses with the lake this high have been very positive, when the lake is above 16 feet, the risk to the dike increases, as does the environmental damage to the lake.
Since Tropical Storm Eta, no water from the lake has gone south. There is still a lot of water from Eta that needs to move out of the southern end of the system, said Kelly. “It will take several weeks before we can start look at potential releases to the south.”
“Flows south are unattainable given with the water that’s in the southern end of the system,” said Kelly. “In January, we may be able to look at flow south again.”
“All of the conservation areas in the south are above schedule,” said Kelly. “Everything in the south is just totally full.”
“Some of the projections look like the lake could drop in a dry environment, getting down to 13 or 14 feet, comparing all of the previous La Niña years back into the 1970s,” he said. “We’re finding La Niña does not always show up,” he added.
“It looks like the lake is going to be higher than we want it” when the 2021 wet season starts, he said.
“We will continue to look at the system holistically and expect to be able to refine the dry season strategy for the South Florida system around February,” said Kelly. “By then, we should have a much better feeling for the effects, if any, of the La Niña, and the results of our gradual transition plan. We’ll be in a better position to evaluate the trends and conditions in the lake, the Everglades and the estuaries, including water supply and our ability to move water south.”