Lake operation plan to change when dike work is complete

Posted 6/25/20

JACKSONVILLE — Work on the Lake Okeechobee Systems Operating Manual continued June 25 with an online meeting of the LOSOM Project Delivery Team (PDT). LOSOM will replace the Lake Okeechobee …

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Lake operation plan to change when dike work is complete


JACKSONVILLE — Work on the Lake Okeechobee Systems Operating Manual continued June 25 with an online meeting of the LOSOM Project Delivery Team (PDT). LOSOM will replace the Lake Okeechobee Regulation Schedule 2008 (LORS ’08) when repairs to the Herbert Hoover Dike are completed in 2022.

Lisa Aley, of the U.S. Army Corps of Engineers Jacksonville District, said performance measures used to develop LOSOM include environmental, recreation and water supply criteria.

Jessica Mallett, engineering lead for LOSOM, said modeling will look at current existing baseline conditions compared to other scenarios.

She said they will use data from lake schedule history from 1965-2016, and evaluate factors such as the rehabilitation of the Herbert Hoover Dike, changes to the Kissimmee River plan which will come with the completion of the Kissimmee River restoration project and the ability to clean water from the lake before it flows into Everglades National Park.

“For LOSOM, our focus is on the central flow path” for receiving Lake O regulatory releases south, she explained.

Additional water storage and flow projects that will come online in the next few years but are separate from Lake Okeechobee will have an impact on LOSOM, she added. These projects include the C-44 Reservoir (with 50,600 acre-feet of water storage) and Stormwater Treatment Area (STA), the Ten Mile Creek Water Preserve Area and STA, the C-23 and C-24 STAs, the C-23 Canal interconnect to the C-44 Canal, the C-43 reservoir (with 170,000 acre-feet of water storage), removal of the old Tamiami Trail as part of the Central Everglades Planning Project (CEPP), and the second phase of raising the Tamiami Trail roadway.

Jim Riley, who presented information on water quality, said there is a lot of stakeholder concern about the potential for algae blooms on Lake Okeechobee.

“The science on the prediction of algae blooms on Lake Okeechobee is not as advanced as we would like it to be,” he said.

He said they working on developing a risk metric, incorporating the best available science.

“The metric we are working uses chlorophyll-a concentrations for estimating phytoplankton abundance as biomass in the water,” he said. They use the concentration of chlorophyll-a in the areas close to Port Mayaca and Moore Haven to assess the risk of algae blooms in water sent east to the St. Lucie Canal and west to the Caloosahatchee River. (Phytoplankton are microscopic plant-like organisms such as cyanobacteria and algae, which make up the base of the marine food web and play a key role in removing carbon dioxide from the air.)

He said algal bloom risk may or may not include toxins.

“Sometimes toxins are produced by an algal blooms, sometimes they are not. Do we know why? No,” said Mr. Riley. “When you hear ‘harmful algal bloom’ it does not mean toxin is present.”

He said Dr. Bill Walker has worked with the top experts in Lake Okeechobee ecology to develop equations for the southwest shore (the littoral zone) and the pelagic zone in the center of the lake.

He said they are trying to find the “sweet spot” to reduce harmful algae bloom risk while not affecting water supply, recreation and environmental health goals.

He said 20 parts per billion (ppb) is a safe standard for chlorophyll-a on Lake Okeechobee while 40 ppb chlorophyll-a indicates a visible “bloom” of algae and/or cyanobacteria on the lake.

Mr. Riley said they are proposing a new metric, which will be reviewed by the Florida Blue Green Algal Task Force.

“Earlier in the year we had several different eco-subteam meetings,” said Dr. Ann Hodgson, who gave the environmental report. They came up with a tentative list of performance measures.

“In the northern estuaries which include the St. Lucie and Caloosahatchee estuaries, we have metrics proposed for high flows and low flows,” she said. They are considering adding metrics for Lake Worth Lagoon flows.

‘For the Lake Okeechobee area, the RECOVER stage metric has been completed, she said. They are developing a performance metric for conditions favorable to snail kites.

The environmental sub-team is also considering performance metrics of the Everglades, the Loxahatchee National Wildlife Refuge, flows to Florida Bay and flows to Biscayne Bay.

“We still don’t seem to have enough water for the environmental uses,” said Drew Martin of the Sierra Club during the public comment period. He said it is important that LOSOM modeling provides enough water for environmental needs, especially during droughts.

Newton Cook of United Waterfowlers said the Everglades Agricultural Area (EAA) would naturally receive the water when the lake was “wet, dry or indifferent” before water flowed south. He said water managers can’t just pick up water and move it around the EAA to flow south. Before the dike was built, “water ran out of the lake into what was the pond apple forest, which is now the EAA,” he said. From there it continued to sheetflow south. “That is what we need. The water needs to continue to flow south,” he said.

Ryan Rossi of the South Florida Water Coalition said the urban areas are concerned about water supply. He said while they are relieved the rainy season prevented a water shortage this year, the water supply is always a concern. “The savings clause guarantees a minimum water supply for all users, including the environment,” he said.

“The rainy season will come in Florida,” said Merrit Mathison, of the City of Stuart. “To think those rains will not come is contradicting history.” He noted the lower level of Lake Okeechobee at the start of the 2020 rainy season provided more capacity in the lake.

“The extra capacity has allowed the lake to absorb tremendous amounts (more than 19 billion gallons) of water from the C-44 Canal,” he said, noting this protected the St. Lucie estuary from the discharge of that local basin runoff.

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