JACKSONVILLE -- “Things are going pretty well,” with Lake Okeechobee, Col. Andrew Kelly, commander of the Jacksonville District of the U.S. Army Corps of Engineers, explained at a March 25 teleconference media briefing.
On Thursday, the lake level was 14.67 feet above sea level, about 0.27 feet lower than last week. Although the Big O is still 2.5 feet higher than it was this time last year, Kelly said they will slightly reduce releases in order to maintain that gradual recession. Starting Saturday, releases to the Caloosahatchee estuaries, measured at the Franklin Lock, will drop from 2,000 cubic feet per second (cfs) to 1,500 cfs. Releases to the St. Lucie River, measured at the St. Lucie Lock, will remain at 500 cfs.
To the south, water flowed out of Lake Okeechobee at an average of 2,543 cfs for the past seven days. Some of that water was for water supply for agricultural and urban uses. Some went to the stormwater treatment areas (STAs) south of the lake, which clean the water before it flows into the Water Conservation Areas (WCAs). Meanwhile, about 1,100 cfs was moving from the WCAs under the Tamiami Trail to Everglades National Park.
Kelly said a gradual recession during the dry season is important to keep the lake’s ecology healthy. Currently, there are 35 snail kite nests on Lake Okeechobee, he explained. If the water level drops too quickly, the nesting season for these endangered birds could be interrupted.
“We’re balancing what we can do and what we should do with the lake and estuaries,” he said.
The lake started the dry season higher than normal due to higher than normal rainfall in November and the heavy rainfall dumped on South Florida by Tropical Storm Eta. Eta flooded the STAs and WCAs south of the lake, making it impossible for more water from the lake to move south until that area had a chance to dry out.
“We worked into a dry season where we tried to maximize the amount of water leaving Lake Okeechobee to be at a reasonable place for Lake Okeechobee by the start of the wet season,” the colonel explained.
The lake is “still higher than we want to be, but the trend is getting better,” he added.
Kelly said the corps is using a deviation to the current lake operation schedule – the Lake Okeechobee Regulation Schedule (LORS) – to release water early in the year when algae is not normally present in order to have more capacity to hold water in the lake later in the hotter summer months when the potential for algal blooms increases.
With the reduction in flow to the Caloosahatchee, “we’re taking one small step back from what we were doing last week, in order to keep the lake recession rate at a good level for the environment and for the birds while also trying to keep the lake going down during the dry season so we can mitigate for lake releases in the fall,” he said.
Decisions on lake releases are made in real time, using the best predictions available concerning rainfall, evapotranspiration, temperature and the potential for harmful algal blooms. (Evapotranspiration is the combination of evaporation plus transpiration of water from plants.)
“We currently have no information that suggests an abnormal algae year,” said Kelly. “It is very, very challenging to predict. The science community is trying to figure that out. We know for a fact that late in the summer when it is hot, potential increases for algae.
“We don’t see algae blooms writ large out there now,” he said. “We have noticed a little bit of algae at S-308 (Port Mayaca Lock), where water is not moving but it is not indicative of a larger algae problem,” he added.
Based on the information available, “we believe using the current strategy, we will be about 13.5 feet by June 1,” said Kelly. If the weather is drier, the lake could potentially go lower than 13.5 feet.
While LORS calls for lake levels that fluctuate from a low of 12.5 feet at the start of the wet season to a high of 15.5 feet at the start of the dry season, the corps is not targeting a lower lake level by June 1, Kelly explained. “We are working with Mother Nature currently to do the best we can.”
The corps anticipates the lake will be higher than normal at the beginning of hurricane season. “We will continue to do what we can do with releases to the estuaries now when there is no algae,” said Kelly.
Even without release to the east, the lake level affects the C-44 basin and the St. Lucie estuary. Last summer, the corps let about 100,000 acre feet of water from the C-44 basin in Martin County backflow into Lake Okeechobee, sparing the St. Lucie that nutrient-rich freshwater flow in the heat of the summer. Freshwater lowers the salinity in the brackish estuaries, which increases the potential of algae blooms. The phosphorus and nitrogen in that runoff can also feed algae blooms. “Last year, we were trying to get out of the wet season without releasing anything at the S-80 (St. Lucie Lock),” Kelly explained.
Water from the lake enters the C-44 (St. Lucie) Canal at Port Mayaca, which is 23.9 miles from the St. Lucie Lock. Flow at Port Mayaca is gravity flow. If the lake is 14 feet or higher, water cannot backflow from the C-44 canal into the lake, and must be released through the St. Lucie Lock to prevent flooding in the basin. But even if the lake is below 14 feet, water managers may not let water from the C-44 backflow into the lake this summer. Kelly said they will have to make that decision based on conditions at the time.
“If there is no algae present, I think we would try to continue to move water out of the lake, and not allow additional water to backflow in,” he explained.
Kelly said they are modeling the effects of backflow at Port Mayaca as part of the discussion underway for the Lake Okeechobee System Operating Manual (LOSOM). LOSOM will replace LORS in 2022 when repairs to the Herbert Hoover Dike are complete.
South of the big lake work on the Everglades Agricultural Area (EAA) reservoir continues at “full speed ahead,” Kelly said. Things are continuing to go as planned. “We are eagerly awaiting the president’s budget and will see how that takes us into the next budget cycle,” he explained. “The South Florida Water Management District is doing an incredible job on the STA portion of the EAA project.” The corps is still in the design phase for the massive reservoir. They hope to let the first construction contracts for some of the inflow and outflow seepage canals later this year.
While the tentative completion date for the expedited schedule for the $3.5 billion EAA reservoir and STA project is 2028, future work will depend on funding, he said. The reservoir project was moved up on the Integrated Delivery Schedule (IDS) for the Comprehensive Everglades Restoration Plan (CERP) after the Florida Legislature passed Senate Bill 10 in 2017.
While the EAA reservoir is an authorized project with an expedited schedule “we can’t anticipate the federal budgets between now and 2028,” said Kelly.