About 250 grass carp are now silently swimming in the waters of Taunton Lake, the scenic 125-acre spring-fed, glacial lake in the Taunton District whose waters drain into Pond Brook and eventually to the Housatonic River.

The grass carp, which are not native to the lake, recently were released into it as part of a project designed to curb the growth of the weed known as aquatic milfoil. Grass carp eat milfoil.

Taunton Lake, which once served as a public water supply reservoir, has only limited public access. Its waters largely have been fished by members of Newtown Fish & Game Club, a group which maintains a private boat launch for its members at Taunton Lake Road.

To spare the lake from water turbulence and turbidity, fishing boat propulsion is limited to low-powered electric trolling motors. Club members also are allowed to fish from shore. Ice fishing is popular. Trout and bass make for prized catches.

The lake has a maximum depth of 30 feet, with an average depth of 22 feet. It has an estimated water volume of 950 million gallons. The lake has an 850-acre watershed.

Taunton Lake has remained a relatively clean water body over the years due to its limited access and because only a fraction of its shoreline has been residentially developed.

In 2007, however, testing indicated that the lake had become infested with aquatic milfoil, an invasive weed that has entered many lakes and ponds in North America.

In this region, Lake Zoar, Lake Lillinonah and Candlewood Lake have heavy milfoil infestations.

It is unclear exactly how the milfoil contamination started in Taunton Lake.

It is thought that boats that had been in use elsewhere picked up milfoil fragments on their hulls in those other waterbodies and then introduced the weed into Taunton Lake.

George Benson, the town director of planning and land use, is an aquatic biologist, or limnologist, by training.

During the past several years, since milfoil was discovered in the lake, Mr Benson has advised the Newtown Fish & Game Club and the Taunton Lake Landowners Association on measures that could be taken to curb the weed’s spread.

As a limnologist, Mr Benson has overseen a successful milfoil control project at the 83-acre Ball Pond in New Fairfield, where grass carp were placed in the water and have been eating milfoil for years, thus controlling the weed.

The 250 grass carp which recently were placed in Taunton Lake are sterile and will not reproduce, preventing  uncontrolled growth of the grass carp population, Mr Benson said.

The need to maintain a certain population of grass carp would require occasional restocking. Grass carp are native to Asia.

Although grass carp are a food fish in China, in Europe and the US the herbivorous fish are used for aquatic weed control.

Rowledge Pond Aquaculture of Newtown did the fish stocking from the fish and game club’s boat launch.

The state Department of Energy and Environmental Protection (DEEP) reviewed the stocking plans and endorsed the project.

The grass carp, which were 10 inches to 12 inches long when placed in the lake, should be effective in controlling milfoil growth for about four to five years, Mr Benson said.

The grass carp are large enough so that they will not be the prey of other fish in the lake.

“They eat the milfoil,” Mr Benson said, describing the simplicity of the approach.

The harvesting of milfoil is sometimes used to control the weed. But that approach can be problematic, Mr Benson said, noting that as the long strands of milfoil are being gathered, the plant breaks into small pieces, with those plant fragments then falling downward into the lake and rerooting on the lakebed.

After milfoil was discovered in Taunton Lake, herbicides were applied, with less than desired results.

Fortunately, no zebra mussels have yet been discovered in Taunton Lake, he said. That small freshwater mussel has become an invasive species across the world.

Big Fish

The grass carp are expected to grow to more than three feet long. They are easy to catch.

The people who are managing the grass carp project ask anyone who catches a grass carp to put it back into the water to let it continue eating milfoil.

A special barrier has been positioned at the lake’s outlet to Pond Brook to prevent the carp from leaving the lake.

Mr Benson said that approximately 28 acres of the 125-acre lake are infested with milfoil. There has been a steady increase of the infested area since milfoil was discovered in the southeastern corner of the lake, he said. When discovered in 2007, about four acres of the lake were contaminated with milfoil.

Milfoil, which has long stems surrounded by feathery foliage, spreads along the shoreline in shallower water where conditions are suitable for its growth, he explained.

Excessive milfoil in a lake tends inhibit others species and damages its wildlife habitat, he said. Mr Benson termed the lake as “moderately” infested with milfoil. 

The dense pockets of milfoil now in the lake would become even denser if measures are not taken to curb its growth, he said.

Besides aesthetic problems, the presence of milfoil impedes fishing, he said.  Also, the propellers of boats that travel through milfoil pockets tear up the milfoil and tend to spread its growth, he said.

By next summer, those monitoring the grass carp stocking project should have some sense of how effective it has been, he said.

Landowners

Pat Barkman of the Taunton Lake Landowners Association, Inc, said the presence of grass carp in the lake probably will not eradicate the milfoil infestation, but would keep the problem in check. Ms Barkman advises the association on conservation issues.

Ms Barkman said she hopes to learn in within two years whether placing the grass carp is an effective way to control the milfoil in Taunton Lake.

Frank Hufner, who heads the fish and game club, said the project to place grass carp in the lake has been in the planning stages for several years.

Besides Mr Benson’s advice on the fish stocking, Town Engineer Ronald Bolmer aided with designing a device to keep the grass carp from leaving the lake by swimming into its outlet, Mr Hufner noted.

Also, DEEP recommended the number of grass carp that should be stocked in the lake.

“We’ve got our fingers crossed. We hope for the best,” Mr Hufner said.

“It should work. We’ve got great expectations,” he said, pointing to the effectiveness of a similar project at Ball Pond.