Despite Lake Okeechobee’s high water level, relatively little water from Lake Okeechobee has been released to the Caloosahatchee River this wet season.
According to the U.S. Army Corps of Engineer data, since the 2023 wet season started on May 15, total flows through the Franklin Lock and Dam have been 87% local basin runoff and just 13% water from Lake Okeechobee.
During the wet season, USACE has maintained an average target flow at the Franklin Lock of 2,000 cubic feet per second (cfs). That’s within the “beneficial flow range” for the estuary. Too little freshwater makes the estuary too saline and too much freshwater makes the estuary too fresh for the health of the plants and animals that live in the estuary.
The Franklin Lock is more than 43 miles from the Julian Keen Jr. Lock at Moore Haven, where the lake connects with the river. If local basin runoff meets or exceeds that 2,000 cfs target flow, no lake water is released. That’s what has happened most of the wet season. Heavy basin rainfall met or exceeded the target. Lake water was only released during dry times when the flow would have fallen before 2,000 cfs with help from the lake.
If and when the rains stop, and the basin dries out, USACE will release lake water to maintain the beneficial freshwater flow needed to keep the Caloosahatchee estuary healthy.
What about the nutrient load in the lake water? According to South Florida Water Management District data, the phosphorus load in the lake water is about the same as the phosphorus load in the basin runoff. Nitrogen levels in the lake water tend to be lower than nitrogen levels in the basin runoff.
According to information shared at meetings of the Blue-Green Algae Task Force, during an average year, lake water makes up 30 to 40% of the Caloosahatchee River flow and 30 to 40% of the phosphorus load. Most of the lake water flow is in the dry season, when the river does not receive sufficient local basin runoff to meet the beneficial flow target to the estuary.