MAHOPAC, N.Y. - The growing weed menace in Lake Mahopac is the worst it’s been in more than two decades and the Lake Mahopac Park District Advisory Board is trying to convince the state Department of Environmental Conservation (DEC) to be proactive on the matter before the problem gets any worse.

The weeds make swimming in the lake unpleasant, if not impossible, and can damage boat propellers and Jet Ski motors.

The Advisory Board met Monday night, Oct. 1, to discuss the issue and the strategies it’s pursuing to remedy the problem.

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The No. 1 tactic the board is employing is trying to convince the DEC to add more weed-eating carp to the lake. Back in 1993-94, when the lake had a weed problem as severe as it is now experiencing, the district spent $33,000 on 2,565 carp and the problem was remedied within a year, said Ed Barnett, chair of the Advisory Board.

“That lasted for 22 years,” Barnett said.

The carp in question are sterile and unable to reproduce, so as they die off they need to be replaced. The Advisory Board would like the DEC to do that on a somewhat regular basis, but it’s not part of the DEC’s standard operating procedure.

Two hundred carp were put in the lake in 2016 and 1,500 were added in 2017.

“That’s not nearly enough,” said board member John Maxwell.

Barnett said the best way to convince the DEC to bring in more carp is by providing the agency with research and data. In August, the Advisory Board flew a drone over the lake and took photos that illustrate the dramatic encroachment of the weeds. The photos will be passed on to the DEC.

The district also performed a biomass study this summer in which water and weed samples were removed from the lake from various locations and sent to a limnologist (a scientist who studies regional waterways and freshwater ecosystems, conducting chemical analysis to understand ecological impact). The limnologist will send the results of the analysis to the DEC.

“We need more fish; it’s a scientific thing,” Barnett said.

Town Councilman Mike Barile said, “With some pressure, maybe [DEC] will do it.” Barile, who sat in on the meeting, said that adding carp “worked once before. It worked great. We basically want more fish.”

Barnett said it was best to take a diplomatic approach with the DEC, rather than become confrontational.

“We are doing it scientifically before we get political,” he said.

Board members noted that the weeds not only cause problems for swimmers and boaters, but they can also wreak havoc on property values for homes around the lake.

“It devalues the homes; there’s no doubt about it,” Barnett said.

Adding to the problem, and perhaps contributing to the cause of the weed issue, is the growing number of geese that inhabit Lake Mahopac and its shoreline.  They poop everywhere, and their feces act as fertilizer for the weeds.

“You can’t go on the lake and you can’t go in your own backyard,” Barile lamented.

To deal with the geese issue, the birds are harvested at a flat rate of $2,900, plus $6.75 per animal for dressing. They are then donated to area food pantries.

The district also tries to reduce the geese population by tracking down the eggs.

“We go out on the islands and find the nests and [shake] the eggs and put them back,” said board member Jim Maxwell.