JACKSONVILLE – Lake Okeechobee, at 15.4 feet above sea level on Feb. 25 is just 0.18 feet lower than it was one month ago. That’s not a good sign in the dry season.
The lake “stabilized more than we would have liked,” Col. Andrew Kelly explained in a media conference call on Feb. 25. “We’re taking a hard look at the recession rate.”
“We’re still kind of in the watch and see mode,” said the colonel who warned the corps may have to release more freshwater from the lake before June 1 if the level stays high.
Currently, the corps is moving about three times the amount of water that would have been released if they strictly adhered to the Lake Okeechobee Regulation Schedule (LORS) which went into effect in 2008. This includes some flow south - in the past week flow from the lake south has averaged about 827 cubic feet per second (cfs).
“We are continuing 2,000 cfs to the west to the Caloosahatchee,” said Kelly. “We’re still at zero to the east to the St. Lucie. As time goes on we might consider releasing some water to the east. We are not there yet. We are keeping an eye on what is happening.”
Mother Nature designed Lake Okeechobee – second largest natural freshwater lake contained entirely within the contiguous 48 states – to recede naturally during the dry season, which starts around Dec. 1 and ends around June 1, and rise slowly during the wet season. According to lake scientists, the most ecologically beneficial range for the lake is a high of 15.5 feet to a low of 12.5 or 12 feet. So ideally, the lake should be around 15.5 feet on Dec. 1 and 12.5 on June 1.
Most of the water that leaves the lake is through evapotranspiration (the process by which water is transferred to the atmosphere by evaporation and by transpiration from plants) and percolation of water through the earth into the aquifer. During the dry season, some water also moves south from the lake through the Everglades Agricultural Area and west to the Caloosahatchee River.
The combination of late wet season rainfall and Tropical Storm Eta made for very wet conditions in late 2020. In November, WCAs received 8 to 10 inches of direct rainfall from Eta. With the WCAs already flooded, water could not move south.
The Caloosahatchee River needs freshwater flow in the dry season. Water enters the river from the lake at Moore Haven. Local basin runoff also drains into the Caloosahatchee River. The flow to the Caloosahatchee estuaries is measured at the Franklin Lock, which is 43.4 miles from Moore Haven. The desire flow at the Franklin Lock ranges from 750 to 2,100 cfs. The ideal salinity levels vary for different parts of the ecology. Overall, levels below 450 cfs are considered harmful to the Caloosahatchee estuaries because the salinity levels in the estuaries are too high. Levels above 2,800 cfs are considered harmful because the salinity levels in the Caloosahatchee estuaries drop too low. How much lake water the river requires depends on how much rainfall the local basin requires. If there is a lot of local basin runoff, less water is released from the lake.
“We’re working with the estuary scientists to make sure we are in the balance,” said Kelly. He said they started the month of February with flow at the Franklin Lock at 1,500 cfs. He said there was some concern at the time about the red tide in the Gulf of Mexico. Red tide is a marine algae so freshwater flow can make conditions less favorable to red tide by lowering the salinity levels. However, nutrients carried in flow from the Caloosahatchee – along with nutrients in coastal runoff – may also help feed the red tide.
Kelly said as the monitoring for the red tide has been ongoing, the scientists were comfortable with increasing freshwater flow at the Franklin Lock to 2,000 cfs. He said previous studies of red tide have found red tide in the Gulf is not connected to freshwater releases from the lake, “but we are mindful and do take those things into consideration.”
The St. Lucie River is connected to the lake by the St. Lucie Canal (the C-44 canal) which connects to the lake at Port Mayaca. The St. Lucie Lock which connects the St. Lucie Canal to the river is 23.9 miles from Port Mayaca.
The St. Lucie River, the St. Lucie Canal, Lake Okeechobee and the Caloosahatchee River make up the Lake Okeechobee Waterway, which allows boat travel across the Florida peninsula.
The St. Lucie River does not need any freshwater flow from the lake. Historically, the St. Lucie was a freshwater river with no connection to the Atlantic Ocean. In 1892, an inlet was dug to provide direct access by boat to the Atlantic Ocean. During the 1900s, the river and its watershed underwent a series of modifications for navigation, flood control and water supply purposes. This changed the freshwater river into a brackish estuary.
When lake levels threaten to become so high they could endanger the stability of the Herbert Hoover Dike, water is released east to tide through the St. Lucie canal. The extra freshwater can be harmful to the St. Lucie estuary because it lowers the salinity levels.
Kelly said so far this wet season, they have not released water from the lake to the St. Lucie. He said they did have the Port Mayaca and St. Lucie gates open for about 5 hours earlier in the week for a scientific study to better understand the movement of sediment. Even with the gates open during that period, the 7 day average flow at the St. Lucie Lock was just 58 cfs.
Kelly said the longer the lake stays above 15 feet, the more likely the corps will have to release water to the St. Lucie. “We will have to make that hard choice in the coming weeks,” he said.
He said they hope to increase flow south of the lake now the water levels in the Water Conservation Areas are coming down. On Feb. 25, flow under the trail 2,200 cfs. As the water levels in the WCAs drop, more water from the stormwater treatment areas (STAs) south of the lake can be moved to the WCAs and more water from the lake can be flowed into those STAs.
Kelly said the EAA reservoir plan is still on track. When completed the 10,000 acre reservoir will be used to store water from Lake Okeechobee which can then be released south to Everglades National Park in the dry season. The reservoir, which will have its own dike, will have the capacity to store 240,000 acre feet of water – that’s about 78 billion gallons or the equivalent of 6.5 inches on Lake Okeechobee.
Kelly said they are committed to getting the first construction contract for the massive project in this calendar year. Construction will be in many phases and is projected to be complete in 2028.
“Folks in my organization are continuing at a breakneck pace continuing on designs,” he said. “We are also working on agreement with SFWMD to enable us to move into the construction phase
“We are eagerly awaiting the president’s budget,” he said. “We are eager to see how projects such as the EAA fare in the upcoming budget.
“Right now there is no deviation from the plan,” he said. “We are still on an expedited schedule.”