Last year, members of the Skaneateles Lake Eurasian Watermilfoil Eradication Corp. did a few test runs. But this year, it's the real deal.

After settling sail from the Mandana boat launch off of Route 41A earlier this month for their first dive of the season, they had only one thing in mind: Kill those weeds.

In recent years, Eurasian watermilfoil, a non-native species, has been spreading rapidly in Skaneateles Lake, generally at depths of approximately eight to 15 feet, according to SLMEC. In the last five years, the number of milfoil patches in the lake has tripled.

Members of SLMEC worry that this will create problems in terms of recreation and aesthetics, not to mention larger, more far-reaching issues.

“The most important reason is that once the milfoil is formally entrenched in the lake ... it will permanently change the ecology of the lake,” said Larry Rothenberg, who founded the nonprofit along with Robert Werner. “Really, that's the end of that kind of pristine cleanliness that we have.”

And so the group, formed in January 2007 at the suggestion of the town's Aquatic Invasive Species Committee, is going forth with a project that it estimates will cost approximately $850,000 over three years.

Though SLMEC is applying for state grants, it hopes to raise $500,000 in private donations for this season's work.

“The more we can get done this year, the easier the task becomes,” Rothenberg said, noting that the group has thus far raised about $100,000.

Project manager John Menapace, owner of Skaneateles Wooden Boat Co. and the man who helped design the two pontoon boats that will be used, said that the plan this season is to go around the lake and try to hit all the milfoil patches at least once.

This should cut down the milfoil enough that divers can sweep the lake twice in 2008, and the third year - and the years thereafter - will primarily be used for monitoring of the real persistent patches.

So how does one go about killing an invasive species? Dig, dig, dig.

From now through October - or as long as the good weather holds out - certified divers will be working five days a week to physically dig up the roots of the milfoil.

“They have to get their hands under the roots, and I guess they call it tickling them up,” Menapace said, noting that the roots come up pretty easily. “If you don't get the whole root, you've basically left the plant, so it's not very effective.”

The divers can stay down a long time because they will be using compressed air and hoses rather than scuba gear. Since they don't need to resurface to fill and change tanks, the record so far is a four-hour dive, Menapace said.

John Wickwire, 62, of Spafford, and Nathan Brady, 20, a student at the State University of New York College of Environmental Science and Forestry, were the first two divers to go down this season.

“I just thought it would be a good way to spend my summer,” said Wickwire, who has been a certified diver since 1991. “I think we're both fortunate that we're kind of on the cutting edge of a very interesting research project.”

SLMEC is fashioning its suction dredging system off of similar programs that have been successful in Upper Saranac and Lake George. The plan is to have two divers going down at a time, each for two-hour shifts. Another diver will be in charge of bagging the plant after the divers below feed the milfoil into a suction hose.

The milfoil will then be distributed to local farmers who can use it for compost.

Additionally, SLMEC is partnering with Syracuse University, where Christopher Scholz, a member of the SLMEC board of directors, is an associate professor in the Department of Earth Sciences. Scholz's graduate students will be investigating the kinds of bottom conditions in which milfoil is prevalent.

So why do this all now? Because, Rothenberg said, Skaneateles Lake and the citizens that use it don't have a time to waste.

The weed grows when pieces that break off take root, and at the rate things are going, there will be a ring of milfoil around the lake in three to five years, Rothenberg explained. This will have an effect on the water clarity and will lead to unnaturally muddy, silty areas close to shore that will create increased algae levels and crowd out more beneficial plants, he said.

“Practically speaking, the problem gets harder to tackle as the weed gains a foothold,” Rothenberg said. “It's still a manageable problem, and in a couple of years, it's likely to become unmanageable.”