SEPTEMBER 1999

FEATURES

Lake Cascade

FSU GEOLOGIST KISH,
INVESTIGATES VANISHING LAKE

By Bill Varian
Reprinted from the Tallahassee Democrat

It has all the making of a prime-time David Copperfield special: Watch the world-famous magician make an entire lake disappear. Trouble is, it would be old hat. Mother Nature pulls this stunt on a fairly regular basis at Lake Cascade on Tallahassee's southwest side, as the people who live near it will testify.

Stephen Kish, an associate professor of geology (at FSU), is trying to unlock the magic that makes Lake Cascade disappear every few years - as it has recently. People who have lived in Leon County long know that its lakes occasionally disappear, even Lake Jackson.

At Jackson, it happens with predictable regularity - about every 25 years. The next occurence will be within the next seven years.

Under the right drought conditions - like what we experienced this past summer and spring - the groundwater table falls, creating a vacuum. The vacuum essentially sucks the lake water into the ground through a hole in the lake's surface, sometimes within a matter of days.

Lake Cascade, just outside Capital Circle Southwest and west of Tallahassee Regional Airport, disappears with much greater frequency, however. It's nearly bone-dry now (published July 5).

Cascade is part of a larger chain of four lakes that includes Lake Bradford, which itself has dropped, but inexplicably only a foot or two compared to the bottoming out at Cascade. The lake level at Cascade started falling in early February, according to nearby residents. By May, it had dropped from its normal 10-to-12-foot depth to a couple of small pools at its edges.

Occasionally the entire Bradford/Cascade chain of lakes dries up. Michael Kasha, an FSU science professor who lives on Bradford, said he once took part in a hike from Bradford west to Aenon Church Road, across lake and swamp bottom. Clumps of cypress trees stand naked. Birds, including blue herons and cattle egrets, arrive and leave quickly, seemingly befuddled by the missing lake. The occasional turtle shell of an unlucky straggler is found.

There are plenty of artifacts: mainly pull-off aluminum beer tabs. Surprisingly, there are few fish carcasses.

"There's a lot of wading birds around here," Kish said. "I think they've taken care of them."

Kish is using a relatively old-fashioned piece of surveying equipment, known as an alidade, to map the lake's bottom. He'll use the measurements to calculate an estimate of the volume of water held by the lake when it's full, and to create a three-dimensional rendering of the lake bottom.

The older technique allows him to better account for dips and rises that are not as easily distinguished from satellite maps. He's also keeping track of how much rain falls and measuring how quickly the water rises. Kish said he suspects that sinkholes do not fully explain the mysterious disappearing lake.

In other lakes, groundwater can also act to stabilize a lake by essentially replenishing it as it evaporates. Residents here are not so sure.

They suspect a separate pool of groundwater, not linked to the other lakes in the chain, accounts for its unique fluctuation. They speak of seeing logs twirl down a sinkhole at the eastern edge of Cascade.

Kish said that, more so than some lakes, Cascade is fed directly by rain. But clearly there's more at work than evaporation. "That's ultimately what we're investigating," Kish said. "We're trying to understand why this lake is so sensitive to variations in rainfall."

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