JACKSONVILLE — The U.S. Army Corps of Engineers (USACE) Jacksonville District plans to make discretionary releases from Lake Okeechobee Feb. 13-16 as part of an ongoing sediment study by the South Florida Water Management District (SFWMD) and the U.S. Geological Survey (USGS) to better understand nutrient and sediment transport to the estuaries under different flow conditions.
The releases will affect the Julian Keen, Jr. Lock and Dam (S-77) and the Port Mayaca Lock and Dam (S-308) as water is released to support the study.
The initial releases are planned for the morning of February 13 at S-77 and are expected to last for a maximum of eight hours, not to exceed 4,000 cubic feet per second (cfs). Sampling will take place February 14 through 15 at S-308 and is expected to last for a maximum of eight hours per day, without exceeding 2,000 cfs. Releases from the S-308 during this time will be captured by the C-44 Reservoir using pump station S-401.
The St. Lucie Lock and Dam (S-80) is not expected to release any water during the test. Sampling will be done at S-77 again on Friday, February 15, and is expected to last for a maximum of eight hours with flows not to exceed 4,000 cfs.
The estimated total volume for the releases at S-77 is 4,600 acre-feet, which is the equivalent of 0.01 feet, a tenth of an inch on the lake. The estimated total volume for the releases at S-308 is 1,060 acre-feet, which is the equivalent of 0.002 feet, less than a tenth of an inch on the lake.
No downstream impacts are expected in the Caloosahatchee River Estuary due to the short duration of the study. No downstream impacts are expected in the St. Lucie Estuary since it is not expected that water will be released into the estuary.
This important research will help us understand the relationship between suspended sediment concentrations, how they originate, how they carry nutrients, and how that might impact algal bloom development and growth. The Corps has executed similar actions several times since 2021 in support of the same study and will work with USGS and SFWMD to adjust flows for these studies should conditions on the lake or in the estuaries change.