Losing the lakes

While low rainfall is certainly a root cause of low lake levels, the causes behind the phenomenon are complex and not the same everywhere.

By BILL COATS

© St. Petersburg Times, published April 23, 2000

The shrinkage of local lakes carries different meanings, depending on who's standing on the shore.

For boaters at Lake Carroll, it means the concrete ramp is too high now. Boats must be launched over the rocks and sand beyond the end of the ramp.

For monitors at lakes Fern, Buck and Mound, it means the official lake levels are a mystery, just when people are most interested. The retreating lakes have left their gauges high and dry.

For fishermen in the know, it means cramped fishing holes this year could lead to bumper crops a few years later.

And for property owners near Tampa Bay Water's well fields, it fires up bitterness that has ebbed and flowed like rain cycles for decades.

"The creeks are down. The rivers are down," said Eileen Hart, a veteran environmentalist who lives on Lake Juanita, next to the Cosme-Odessa well field. "They shouldn't be pumping any of them."

John Crilly, who is retired on his family homestead at Lutz's Lake Stemper, recalled that, "My dad, he died in 1978 and he was still cussing St. Petersburg."

That city's wells began sucking up seawater in the 1920s, and it has depended on well fields to the north ever since.

Today, much of Tampa Bay relies on well field pumping. The population, and consequently, the pumps, are running at all-time highs in a region thirsting for rain.

"Hurricane Floyd didn't come last year," explained Terence Owen, who helps monitor the health of Lake Carroll. "He went up to Carolina instead."

Since then, rain has been scant, even for the dry season. Only 3 inches have fallen in Tampa so far this year, compared with a normal 9.

About a third of the area's lakes consequently have shrunk below their official drought levels, which water authorities call the "extreme low minimum." Others are only fractions of an inch higher. (See How lakes have dropped, page 3.) Mud that was several feet deep under El Nino's floods two years ago is sun-dried and cracking now.

Underground, 30 of Tampa Bay Water's 31 key monitoring wells reflect aquifer levels that are below government targets, said AlisonAdams, manager of the agency's resource optimization department. Some have dropped 6 to 8 feet below the targets; some are a half-foot, she said.

She said this area's best aquifer levels are beneath Keystone, Odessa and Citrus Park. The worst are beneath New Tampa, Adams said. The aquifer near Section 21 has been 5 feet below the target, she said.

'No longer swamp'

Lake watchers disagree how far the current lake levels have fallen -- if at all -- beyond history's cyclical lows.

"People who have lived on the lake 20 years say this is the lowest they've ever seen it," moaned Bob Austin, who monitors Lutz's Lake Wilson.

"I've lived on Lake Carroll since '64," said Owen, "and I have never seen it this low. Never."

Art Hackett, who monitors Carrollwood's White Trout Lake, measured it Thursday at 32.35 feet, just below drought level and the lowest level since residents began keeping records in 1971.

But Paul Bearss, who has lived on Lake Magdalene since he was born there in 1916, said he certainly has seen its water lower.

"In 1973, I think it was, you could just drive your car out in the middle and do anything you wanted," Bearss said.

Balloonist Phil Sekora, who pilots his Big Red Balloon over north Hillsborough lakes more than 100 times a year, remembers the mornings five years ago when he floated over Lake Stemper and saw children's bicycle tracks lacing the exposed lake bed. Stemper had shrunk into three separate ponds.

"Nowadays, I frankly don't see a whole heck of a lot of low lakes," Sekora said.

He said big lakes like Stemper and Keystone look healthy. But Lake Starvation and smaller lakes in Tampa Bay Water's Section 21 well field have dropped noticeably. Pumping at Section 21 increased 44 percent in March.

"The areas that were swamp, they're no longer swamp," Sekora said. "They're dry."

Carlos Fernandes, Hillsborough County's lake and stream programs coordinator, said "Water is so low, it's basically a concentrated soup."

"I would say the association between the dry weather and the additional pumping of the wells is an unfortunate combination for the lakes," Fernandes said.

Hart, the Keystone environmentalist, said the lakes are only the visible aspect of a huge system of streams and swamps that should nourish the aquifer, but are drying. "All of Florida's just being continually bled down," said Hart. "You can see these open bodies of water. You can see how the damage is happening."

A green banquet

Besides drought and pumping, subtler factors influence how lakes shrink.

Bigger lakes tend to be sturdier because they have more sources, such as streams, springs and groundwater, said Michael Hancock, an engineer for the Southwest Florida Water Management District.

Smaller lakes hold up if they have sources beyond ground water, or if their outfalls are controlled by culverts, gates or other structures, Hancock said.

Odessa's chain of lakes Pretty, Josephine and Rock benefit from both assets. From the north, Rocky Creek flows into Rock, then Josephine, then Pretty. At the south end of Pretty, Swiftmud manages a gate.

Another important variable is an underground layer of dark gray clay. Through much of Tampa Bay, this clay separates high-level groundwater from the lower-level Floridan Aquifer, the source of drinking water. The clay slows the seeping of groundwater down to the deeper aquifer, holding it closer to the surface and reinforcing lakes.

A 1996 Swiftmud study found the clay's thickness varied greatly. Generally, it was thicker than 40 feet beneath Town "N Country, but thinner than 7 feet beneath Lutz and Carrollwood. In two places, test wells found clay thicker than 35 feet within a half mile of spots where it was absent altogether.

Finally, some lakes are partly refilled, where homeowner groups have obtained permits to "augment" them from wells. Hancock said those lakes tend to stay at a minimum level.

"Every lake has its own story, and there are exceptions," Hancock said. "Rainfall is always the dominating factor. When it's low, it tends to amplify these other effects."

For the lakes' fish populations, low rainfall can be the first step of a revitalization.

Wet relief

"It's actually very beneficial to the lake," said Phil Chapman, a fishery biologist with the Florida Fish and Wildlife Conservation Commission.

When lake waters recede, they expose decaying muck to sun and air. The muck eventually dries, breaks apart and scatters in breezes, leaving healthier sandy soil in the sunlight. Simultaneously, plants that normally sprout at the water's fringe spread down the open lake beds.

Whenever rain resumes and the lakes rise to normal levels, a green banquet awaits the fish.

"All our premier fisheries around the state are driven by these flood and drought cycles," Chapman said.

Weather watchers say this drought cycle, while severe, may be short-lived.

"For May, it's looking like there'll be normal rain," said Scott Goodrick, a meteorologist with the state Division of Forestry.

A normal May would bring only 3 inches of rain, but this year, that would double the rain total.

Similarly, the federal Climate Prediction Center forecasts normal rain into July. Then, at the peak of the rainy season, it predicts above normal rain, continuing into November.

But while dryness prevails, lake lovers fret.

"They're concerned right now," said Austin, the Lake Wilson resident. "They're pumping daily. In the 15 years I've lived on that lake, it's never recovered. It's constantly dropped down."

"At the rate things are going, there'll probably be meetings soon," said Keystone's Hart.

"They don't like it," 84-year-old Paul Bearss said of his neighbors on Lake Magdalene. "But there's not anything they can do about it as long as there's no rain."

-- Bill Coats can be reached at 226-3469 or coats@sptimes.com.

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