JACKSONVILLE – The U.S. Army Corps of Engineers Jacksonville District will reduce Lake Okeechobee releases to coastal estuaries beginning Saturday, April 3.
On Friday, the corps announced plans to reduce the flow to the Caloosahatchee River, measured at the W.P. Franklin Lock, from 1,500 cubic feet per second to 1,200 cfs. They will also reduce the releases to the St. Lucie River, measured at the St. Lucie Lock, from 500 cfs to 300 cfs.
Some of the water included in the measured flow may be local basin runoff. Releases to the St. Lucie River are measured at the St. Lucie Lock, which is 23.9 miles from Port Mayca, where the lake water enters the St. Lucie Canal. Releases to the Caloosahatchee are measured at the Franklin Lock, which is 43.4 miles from Moore Haven, where the Lake Okeechobee water enters the Caloosahatchee River.
The releases are being continued as part of a planned deviation approved in September 2020 to reduce the risk of lake releases when harmful algal blooms are more likely to be present this summer. The deviation has released about 80,500 acre feet of additional water from the lake since it began in February. That’s the equivalent of 26 billion gallons of water – or a little more than 2 inches on Lake Okeechobee.
One of the requirements for using the Harmful Algal Bloom deviation is for USACE to maintain a recession rate of no more than 0.5 feet per month to avoid harm to nesting birds. On Friday, the lake stage was at 14.44 feet. The lake has fallen 0.87 feet in the past 30 days, but is still 2.61 feet higher than it was one year ago and 2.58 feet higher than it was two years ago. The releases will be re-evaluated regularly as conditions in the system change.
On hot sunny days, most of the water that leaves the lake does so through evapotranspiration into the air and percolation into the aquifer.
“We constantly monitor conditions around Lake Okeechobee, and as evapotranspiration and dry conditions have accelerated the lake recession, we are reducing our releases to protect the nesting birds that have returned to the lake in large numbers for the first time in several years,” said Col. Andrew Kelly, Jacksonville District commander. “The lake is higher than we would like, but we must try to balance the ecology of the lake as well as the northern estuaries as we make efforts to reduce the lake level before the onset of the wet season.”
Recently, water managers have been able to send more water south, and the southern portion of the system has begun to return to more normal levels. The very wet Fall of 2020 limited the flows south earlier in the dry season. The corps continues to provide water to the south for the Everglades as well as for agricultural and urban water users.
Recent satellite images show conditions are at a low potential for algal blooms on Lake Okeechobee.
An isolate algal bloom was found in a stagant area of the Port Mayaca (S-308) water control structure. The Florida Department of Environmental Protection algae dashboard shows results from samples taken near S-308 detected low presence of the cyanobacteria Microsystis aeruginsoa. Toxin levels measured were 0.79 micrograms per liter on March 29. The World Health Organization considers levels of microcystin above 1 microgram to be unsafe to drink and levels above 8 micrograms to be unsafe for human recreational contact.
Warning signs were placed around USACE structures and facilities, the USACE website was updated, and operators continue daily monitoring.
For more information on water level and flows data for Lake Okeechobee, visit the Corps’ water management website at http://www.saj.usace.army.mil/Missions/CivilWorks/WaterManagement.aspx.