Several agencies are looking at ways to control water fern growth in Little Lake Wilson. So far, spraying seems to produce the best results.
By BILL COATS
Published January 9, 2004
LUTZ - Last October, four government agencies and a county commissioner agreed to get to the origins of Little Lake Wilson's pollution by testing samples as it flowed into the lake.
But there was one problem. About that time, the pollution stopped flowing into the lake. Everything else did, too, because the rain stopped.
Richard Boler, an environmental scientist with the Hillsborough County Environmental Protection Commission, rushed to Lutz during a Sunday morning thunderstorm in December, hoping to scoop up stormwater samples. But the rain wasn't enough.
"It barely wet the bottom of the ditches," he said.
Testing is critical because nobody is prepared to accept blame for the lake's infestation of salvinia minima, or water fern, which seems to amplify after every rainy spell. The only solution may be a retention pond, which would require a significant piece of land.
And more than the health of Little Lake Wilson is at stake. It forms the headwaters of a chain of lakes that drains toward the northwest, then through Cheval into Rocky Creek and Tampa Bay.
Dredged from swamp in the 1940s, Little Lake Wilson really is a spidery linkage of coves. Boler, who has worked for the EPC for 27 years, remembers Little Lake Wilson's water fern problem as far back as the 1980s. The 7-acre lake is ideal for the weed, which thrives in calm, wind-shielded water.
The problem has vacillated with rain. In the early 1990s, a period of drought, the water fern was relatively tame. Then came the El Nino rains of 1997-98, and the problem exploded. Residents blamed the Department of Transportation, which had just widened N Dale Mabry Highway beside the lake.
The road's drainage system was engineered to decrease the flow into Little Lake Wilson during major thunderstorms, but increase it during ordinary ones.
When Dale Mabry had two lanes, water drained through a pipe under the road from a dense cypress swamp on the west to Little Lake Wilson on the east. Cypress swamps cleanse many pollutants out of water as it meanders through them.
The widened Dale Mabry paved over much of that swamp. The pipe was lengthened, connecting to a network of culverts that drain more directly from an office center, two convenience stores and two horse farms.
The horse farms are a prime suspect for whatever's fertilizing the water fern. Boler's testing has shown that bacteria in the lake's water comes primarily from mammals.
Like other lakes, Little Lake Wilson received an infusion of new water, and pollution, from heavy rains of the past two summers. That triggered a new surge of water fern in the lake and angst along its shoreline.
Residents enlisted the help of Hillsborough County's lakes and streams coordinator, Carlos Fernandes, who encouraged them to clear out water fern and other invasive plants. Fernandes also persuaded the county to replace a crushed pipe that connected the lake under Geraci Road to its big brother, the 54-acre Lake Wilson. The county installed a plastic screen at the pipe's entrance to block water fern.
Nevertheless, the new connection mobilized the larger lake's residents, who worry that pollution will creep from the little lake to the big one. They enlisted county Commissioner Ken Hagan, who brought the state and county agencies together.
"We've gotten their attention that we have a problem," said Olivia Mead, president of the Wilson Lakes Neighborhood Association. "We've gotten a verbal commitment to get it cleared up."
As neighbors lobbied for government help, they also tackled the problem on their own. In the summer, the Wilson Lakes Neighborhood Association marshaled the community to scoop water fern out of Little Lake Wilson.
"We had 70 people out there over a four-weekend period, clearing this stuff out, breaking our backs," Mead said.
But small patches of water fern, which can quadruple its mass every week, remained. In four weeks, it had fully recovered.
That prompted the neighborhood to undertake herbicide spraying. It's controversial, partly because killing water fern converts it into more fertilizer in the lake.
Mead and most residents believe they have no choice. Letting water fern grow means even more water fern will die, wrecking the lake's chemistry worse.
Lately, the lake's fingers have been mostly covered with the weed, but its open areas have been mostly clear.
Bob Terrill Jr., owner of Weedbusters Inc. of Palm Harbor, sprayed the water fern again Monday and was encouraged by the results. He hopes to reduce the weed to a level that would require spraying only twice a year.
"If I got it under control for them, they should be able to do it themselves," Terrill said.
