Corps to release Lake Okeechobee water to St. Lucie River

Posted 1/20/23

With Lake Okeechobee still more than half a foot above the upper limit of the lake’s ecological envelope...

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Corps to release Lake Okeechobee water to St. Lucie River

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With Lake Okeechobee still more than half a foot above the upper limit of the lake’s ecological envelope, the U.S. Army Corps of Engineers started lake releases to the St. Lucie River on  Jan. 21. This is first time lake water has been released to the St. Lucie since April 2021.

Until further notice, a flow of 500 cubic feet per second (cfs) will be released, measured at the St. Lucie Lock.

The Lake Okeechobee Waterway extends from coast to coast. This map shows the locations of the locks on the Lake Okeechobee Waterway.
The Lake Okeechobee Waterway extends from coast to coast. This map shows the locations of the locks on the Lake Okeechobee Waterway.

On Jan. 20, Lake O was 16.10 feet above sea level. The ecological envelope for the big lake ranges from a low of 12 to 12.5 feet to a high of 15.5 feet. When the lake level is at 15.5 feet, the marshy areas around the second largest freshwater lake within the continental United State are inundated with water. As the lake level rises higher, the water stacks up against the side of the Herbert Hoover Dike – an earthern berm that encircles the Big O for flood control.

Over the past month, the lake level has been slowly declining but the level is not receding fast enough, Col. James Booth, commander of the U.S, Army Corps of Engineers Jacksonville District explained in a Jan. 20 media call.

The lake has not recovered from the inflow of about 1 million acre feet of water that flowed and/or was pumped into the Big O following Hurricane Ian. Booth said they need to lower the lake before the next wet season in order to have capacity for water from future storms.

For the seven-day period ending Jan. 20, flow into Lake Okeechobee was about 2,100 cubic feet per second, with most of that water coming down the Kissimmee River from the Kissimmee Chain of Lakes near Orlando.

Flow west to the Caloosahatchee River averaged 2,000 cfs. That flow, which is measured at the Franklin Lock, is a combination of lake releases and local basin runoff.

Flow south averaged 1,249 cfs.

Prior to Jan. 21, no lake water had been released east to the St. Lucie since April 2021.

Booth said water managers have been watching the lake level and have re-evaluated the dry season strategy.

“We haven’t seen the recession as much as we would like,” he explained. In order to bring the lake level down before the 2023 wet season, USACE will continue the 2,000 cfs releases to the Caloosahatchee and will add 500 cfs steady releases to the St. Lucie River (measured at the S-80 lock), and also send 100 cfs to the Lake Worth Lagoon.

Booth said they are adjusting the plan based on changes in the weather forecast which they expect to transition from the dry La Niña conditions to netural conditions much sooner than originally expected.

Releasing more lake water now will reduce the chance of harmful releases in the summer when the risk of algal blooms is higher, the colonel explained.

He said with the additional releases, they hope to get the Lake O level down to 13 to 14 feet by June 1.

South of the lake, about 1,800 cfs is flowing under the Tamiami Trail to Everglades National Park. Under a federal consent decree, water must be cleaned to less than 10 parts per billion phosphorus before it can be released to the park. Due to the extra nutrient load that flowed into Lake O from Hurricane Ian and the stirring of lake bottom during Hurricane Ian and Hurricane Nicole, Lake Okeechobee water is estimated to be 10 to 20 times higher in phosphorus (or more) than the level allowed to flow under the Tamiami Trail.

Booth said the Everglades Agricultural Area stormwater treatment areas (STAs) south of the lake have very little capacity to accept and treat water from the lake. The STAs were also hard hit by the hurricanes.

During the dry season, the South Florida Water Management District (SFWMD) needs to let the STAs dry out to recover from the wet season. In some areas, they also need to replant vegetation.

“Those STAs were run pretty hard,” said Booth. “They had a lot of flow coming in. You can’t just run them hard and not give them any rest. You have to let them dry out.”

He said even in a normal year, there is little capacity for the STAs to accept water from Lake Okeechobee in the dry season because the STAs need to dry out.

How much water the STAs can accept depends on the health of the STAs, Booth said.

“Lake Okeechobee has not receded as much as we would like since November,” said Booth. “We must prepare for the next wet season, and the latest forecasts indicate we may not have as much help from mother nature as originally thought. Our partners and stakeholders have expressed that if releasing water is required, now is better than later for a variety of reasons.”

Lake Okeechobee, releases, St. Lucie

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