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All choked up

In simpler times, the surface of Little Lake Wilson was clear. Now it's mostly covered with water fern. The lake bottom was clean and sandy. Now it's a slimy black muck.

"If you slip in it, you'll sink up to your knees," warns resident Kelly Polk. "In the summer, when the rains come, there's just an iridescent sheen on this lake."

People have lived around Little Lake Wilson for 30 years, but residents say the lake's decline is new. It followed two events:

First, N Dale Mabry Highway, which skirts the northwestern corner of the lake, was widened to four lanes in the mid 1990s.

Second, years of on-and-off drought ended in 1997 when a rainy El Nino winter arrived.

Water pouring into Little Lake Wilson from Dale Mabry's new drainage system apparently changed the water chemistry, and algae and water fern exploded across the surface.

Residents organized work crews to skim it off. One neighbor, Mollie Agnew, used some of the refuse to mulch a huge flower bed 6 inches deep.

The water fern, fed by fertilizerlike nutrients, didn't recede until drought returned and inflows into the lake stopped. Now El Nino has resumed, and so have Little Lake Wilson's pollution and plant problems.

But in this round, the frustrated neighbors have new allies.

Carlos Fernandes, an environmental scientist who coordinates the county's lake management programs, has become the first government official to blame the road construction for the problems.

Fernandes relies partly on calculations issued by the Florida Department of Transportation to defend its engineering. The DOT numbers show that Dale Mabry's new drainage system should decrease the water flowing into the lake during the heaviest rains, but would allow 23 percent more during ordinary thunderstorms.

"The purpose of the stormwater program is anti-flooding, not anti-pollution," Fernandes told a neighborhood group in January.

Faster, dirtier

Fernandes believes a major cause of the pollution is water flowing untreated under Dale Mabry.

Even when Dale Mabry was only two lanes, a 36-inch-wide pipe carried rainwater under the road from a ditch on the west side to a corner of Little Lake Wilson on the east side. When the road was widened, adding two lanes along its western flank, the pipe was extended.

Rainwater flows from 39 acres into the pipe. It comes from the roofs and parking lots of two convenience stores, a lawnmower shop and a small office park. It comes from the four lanes of Dale Mabry. It comes from patches of woods and swamps. And it comes from two horse farms.

The woods today are remnants of much larger ones that were replaced by the wider road.

"All that was a swampy, mucklike cypress bog," recalls Bob Alexander, who has lived on Little Lake Wilson since 1971.

The DOT's engineers say they have limited the new drainage system to the same volume of water as before. Maybe so, Fernandes responded. But if that water is arriving faster, then it's arriving dirtier.

This is the fundamental concept of retention ponds. Stalling a water flow helps cleanse it. Some of the water and oily pollutants evaporate. Heavier impurities sink into the bottom soil. When water meandered through woods and swamps on its way to Little Lake Wilson, the vegetation filtered pollutants out of it.

"It was coming through sheet flow, which was a much slower process which allowed the water to percolate," Fernandes said.

The DOT contends it didn't speed up the runoff.

"There should be no more water going under the highway with any greater velocity or volume than there was before," said Dwayne Kile, the DOT's design engineer for the Tampa Bay district.

He also noted that other changes in the area, such as construction of the office park three years ago, can accelerate water flow.

Files at the Florida Department of Environmental Regulation show the drainage plan was approved in 1994, with little if any questioning of the drainage into Little Lake Wilson.

The Southwest Florida Water Management District approved the drainage system for flood-control purposes.

"They built what they said they were going to build, and what we permitted," said Michael Molligan, Swiftmud's spokesman.

New protesters

Fernandes has tried to help improve the lake. Through a grant, he hired workers to rip out non-native Brazilian peppers last year. Fernandes is leading the neighborhood in an effort to plant native shoreline vegetation, which will compete for the nutrients that now feed the water fern.

To prevent floods, Fernandes persuaded the county to replace a long-crushed pipe linking the 7-acre Little Lake Wilson with the 54-acre Lake Wilson, its big brother to the east.

That drew a large new group of protesters into the pollution debate. Leaders of the Wilson Lakes Civic Association now fear the new pipe will convey pollution to the bigger lake, and from there into a somewhat circular flow across northern Lutz, through Cheval into Rocky Creek, which flows into Tampa Bay.

"All of that stuff that comes directly into Little Lake Wilson is going to have a downstream effect," complained Bob Austin, a resident who monitors Lake Wilson's quality for the statewide Lakewatch program.

An outcry from the lakes association convinced County Commissioner Jim Norman to get involved. He wrote to the DOT two weeks ago, essentially mirroring Fernandes' concerns and offering to facilitate a solution. DOT staffers arranged a meeting with Fernandes for this week.

Fernandes thinks the DOT should create a detour for the water running into Little Lake Wilson, perhaps into a retention pond. A cheaper improvement, costing up to $50,000 would be a "baffle box" on the 36-inch pipe, which would delay the water somewhat and would contain a barrier capturing floating pollutants.

For the residents along the larger lake, Fernandes already has installed a barrier at the new pipe connecting the two lakes. It lets water, but not water fern, flow through.

While Little Lake Wilson is cursed by water fern, Lake Wilson is blessed by it. Between the time polluted water enters Little Lake Wilson on the west and passes into big Lake Wilson on the east, the invasive weed is consuming most of the water's phosphorus and nitrogen.

Water flowing into Lake Wilson "is as clean as clean can be," Fernandes said.

If water fern didn't blanket much of Little Lake Wilson, algae or some other plant would.

"We're never going to get a handle on it until we can control what goes into the lake," said Alexander.

All the experts agree that most lakefront residents contribute to the pollution of their own lakes. This happens when they fertilize lawns, fail to maintain septic tanks and spread sod _ or worse, sand _ down to the water line. Lakes need buffers of native shoreline plants to filter pollutions from rain runoff. Sod and sand allow rainwater to flow fast and dirty into the lake.

"Everybody is responsible" for situations like Little Lake Wilson, Fernandes said. "The pipe is not the only culprit in this thing, but it is the No. 1."

_ Bill Coats can be reached at (813) 269-5309 or coatssptimes.com.

Mollie Agnew has lived on Little Lake Wilson since 1983. "We would look down and see the fish swimming and everything. We sure didn't have this scum."

Little Lake Wilson's ally, Hillsborough lakes manager Carlos Fernandes, persuaded the county to restore a link from Little Lake Wilson to Lake Wilson. That ruffled feathers, and now the DOT is involved. The barrier shown lets water, but not water fern, flow through.

When Dale Mabry was widened, the drainage system changed. A faster water flow would be dirtier. But DOT engineers say they did not change the speed or volume. DOT design engineer Dwayne Kile noted that other changes in the area could have hastened the flow.

Circular flow

About 43 acres of farms, swamps and pavement drain eastward into Little Lake Wilson. Last year, a blocked connection to the larger Lake Wilson was reopened. That puts Little Lake Wilson at the source of a water flow that again crosses Dale Mabry Highway and runs from Heritage Harbor into Cheval.

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