Corps tries to optimize lake plan

'Optimization' plans would keep lake higher longer

Posted 10/26/21

How will the new schedule for managing Lake Okeechobee impact the lake’s health, water supply and releases to ...

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Corps tries to optimize lake plan

'Optimization' plans would keep lake higher longer

Posted

How will the new schedule for managing Lake Okeechobee impact the lake’s health, water supply and releases to the coastal estuaries?

The optimization plans presented at the Oct. 26 Lake Okeechobee System Operating Manual (LOSOM) Project Delivery Team (PDT) virtual meeting did not improve conditions for Lake Okeechobee’s ecology.

“These plans have taken a step back from paying attention to the ecology of the lake and the grasses we need in the lake to filter the lake,” said Scott Martin of Anglers for Lake Okeechobee.

“The number that concerns me the most is the amount of time over 16 feet,” he said. He said the plans don’t address the health of the lake.

“A lot of times we worry about how much water is being discharged east and west but not about what the high water is going to do to the submerged vegetation” When we lose the submerged aquatic vegetation, it takes a long time to recover, he said

He said while he knows there is a concern about the need to reduce harmful freshwater releases east and west, “we can’t kill Lake Okeechobee in the process.

“If we keep this lake at this extreme high level, we are going to lose all of our filter in the lake.

“Once we lose that vegetation in the lake, it’s over,” he said.

“We’ve somehow treated Lake Okeechobee as a holding lake and no one’s concerned about how much vegetation we’re going to lose,” Martin said.

Managing the lake level over 16 feet 20% of the time will destroy the lake’s ecology, he said.

“While we see an opportunity to do some great things with LOSOM, we aren’t going to be able to do everything everyone wants,” Col. James Booth, commander of the USACE Jacksonville District, explained during the Oct. 26 Lake Okeechobee System Operating Manual (LOSOM) Project Delivery Team (PDT) virtual meeting.

In late 2022, when the repairs to the Herbert Hoover Dike are complete, LOSOM will replace the Lake Okeechobee Regulation Schedule (LORS) which went into effect in 2008. LOSOM will be used to manage the lake levels until the Everglades Agricultural Areas (EAA) reservoir is complete, which is currently estimated around 2028-2030.

“LOSOM will outperform the LORS’08 schedule, but there is only so much a regulation schedule can do,” Booth explained.

LOSOM will include both a schedule setting a desired range of high and low lake levels, as well as release options and operational guidance.

During the virtual meeting, U.S. Army Corps of Engineers (USACE) officials reviewed the most recent modeling of potential “tweaks” designed to get the most benefit from the new operating plan.

Over the past two years, with the help of the LOSOM PDT, the corps developed a variety of lake schedule options, which they initially labeled, AA, BB, CC ... etc. After thousands of computer models and many hours of discussion, in July 2021 option CC, which cuts lake releases to the St. Lucie Estuaries, was chosen. This option was popular with east coast residents, but drew opposition from west coast residents, who objected to increased flows to the Caloosahatchee River, and from those concerned about the health of Lake Okeechobee. While LORS set the high water level for Lake O at 15.5 feet, option CC raises that bar to 17 feet. Lake advocates argued that levels above 16 feet are harmful to the lake’s ecology, killing off the marshes and submerged aquatic vegetation that helps clean the water and provides critical habitat for fish and wildlife.

After choosing option CC, the corps then began a process of optimization with seven goals:
• Recognize the Seminole Tribe as a separate and distinct water supply user;
• Reduce stress to the Caloosahatchee River and estuaries from high volume lake releases;
• Help lake ecology by addressing the duration and number of events over 17 feet;
• Stay as good as or better for water supply;
• Add flexibility in the lower portions of the lake schedule;
• Send more water south;
• Address concerns about cyanobacteria (blue-green algae);

“Phase 1 modeling is an incremental step,” said Jessica Mallet, USACE engineering lead. “It’s a rest stop on the road to optimization.”

Mallet said they looked at increasing flexibility in releases when the lake is low, and added beneficial dry season flows to the Lake Worth Lagoon for water supply.

“The Tribal entitlement volume is not being subject to cutbacks during water shortages,” she explained.

USACE Environmental Engineer Lisa Aley explained they started with about 240,000 computer model runs. Of those 707 met the optimization goals. From those, they narrowed it down to eight runs.

For the lake ecology objective, the criteria used was to keep the period of time the lake is above 17 feet at 2% or less.

She said the eight plans look and work differently, but meet the optimization goals. All of the plans are worse for the lake ecology than LORS as they allow the lake level to go above 16 feet more often and for longer periods.

The lake is currently above 16 feet, 4.4% of the time according to the data presented at the meeting. Plan CC has the lake above 16 feet, 9.8% of the time. The eight optimization plans allow the lake above 16 feet from 12.8% to 19.9% of the time.

Timothy Breen of FWC said the plan looks like the ecology of Lake Okeechobee is at the bottom on the list of priorities.

“We are concerned about the high levels,” said Okeechobee Mayor Dowling Watford. He thanked the corps for improving water supply.

“It all boils down to infrastructure,” said Mike Conner. “We’re trying to shove 10 gallons of water into a six gallon bag.”

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