Lake Jackson, a 4,000-acre lake just outside Tallahassee, Florida, drained into underground caves through a sinkhole in its floor over the course of several months. The lake, which once held about 12 billion gallons of water, is now largely exposed mud and sediment. The drain began in late November 2025, after months of drought in the region, and continued into early 2026. By March, vegetation was growing across the exposed lake bed.

The lake sits inside a closed basin with no rivers or streams feeding it. It fills primarily by rainfall and drains through two natural sinkholes in its floor, known as Lime Sink and Porter Sink. When sediment plugs these openings, the lake holds water. When the plugs give way, the water drains into the limestone aquifer below.

State geologist Harley Means of the Florida Geological Survey described the process as similar to a checking account, in which rainfall deposits and drainage withdrawals determine the water level. Florida sits on porous limestone, and the underground system beneath Lake Jackson is an active cave network.

A 2018 dye-tracing study led by Dr. Shawn McGlynn of McGlynn Laboratories tracked water from Porter Sink to Wakulla Spring, about 19 miles south. The water traveled through the Upper Florida Aquifer, surfacing at the spring about 35 days later. The current drainage is expected to follow the same route.

Wakulla Spring is a first-magnitude spring and is already on Florida’s impaired waters list due to existing water quality issues. McGlynn, who chairs the Wakulla Springs Alliance, said the lake needs consistent rainfall events of three to six inches to maintain water levels above the sinkhole. Forecasts of one to three inches from an approaching cold front, he said, would likely not be enough to keep the basin flooded.

The aquifer beneath the region also supplies drinking water to nearly 400,000 people in the Tallahassee area.

Lake Jackson has drained repeatedly throughout recorded history. The documented record includes events in 1829, 1907, 1932, 1957, and 1982, for an average of roughly once per generation. Since the late 1990s, however, the lake has drained partially or fully in 1999, 2001, 2006, 2012, 2021, and 2025. The interval between drain events has shortened considerably.

The 2025 drain occurred during the worst drought in Tallahassee’s recorded history. In February 2025, the Northwest Florida Water Management District issued a water shortage warning, only the third such order in its 26-year history. All five water management districts in Florida were under shortage warnings at the same time.

The lower water levels have affected local fishing. Fish populations, including bluegill, largemouth bass, and gar, have concentrated in deeper pools in two areas of the lake as their habitat has shrunk. Chris Paxton, a biologist with the Florida Fish and Wildlife Conservation Commission, said the ecosystem is expected to benefit when the lake refills, with renewed vegetation and sediment, but he did not specify a timeline for recovery.

Cypress trees along the shoreline now stand in dry air with exposed trunks, and a bobcat was photographed crossing a former boat ramp. A similar pattern was reported at Cascade Lake near Tallahassee International Airport, where cypress trunks also stand exposed.

The sinkhole at Porter Sink does not remain open indefinitely. Sediment typically re-plugs the opening after each dry down, as it has for at least two centuries. The timeline for resealing, however, is not predictable.

The questions raised by the current drainage are whether the cycle is accelerating and what it means for the underground system that supplies drinking water to the region and feeds Wakulla Spring. The lake has refilled after past drainages, often following a tropical system. Whether that occurs this time depends on rainfall in the coming months.