Last fall, 250 grass carp were placed in the waters of Taunton Lake, a scenic 124-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, 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.

To gauge conditions in the lake, the Connecticut Agricultural Experiment Station is conducting a study of its current milfoil infestation.

George Benson, town director of planning and land use, said the town requested that the experiment station document weed conditions in the lake.

Sara Benson and Samantha Wysocki, who are seasonal research assistants for the experiment station, have been gathering data to be used to map current conditions. The two women plied the waters of the lake last week in a power boat collecting data on the nuisance weed’s location and density. Ms Benson is Mr Benson’s daughter.

The two women work for the experiment station’s Invasive Aquatic Plant Program, which is headed by scientist Gregory Bugbee.

Weed mapping is expected to be done by early next year and will be posted on the Internet for public review.

Milfoil infestation in the lake is present in shallower areas where the water is less than 13 feet deep, Mr Benson said.

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, 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.

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 Eurasian 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 infested waterbodies and then inadvertently introduced the weed into Taunton Lake.

Mr Benson is a limnologist by training, specializing in the science of fresh bodies of water.

He 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 that were released in Taunton Lake last fall are sterile and will not reproduce, preventing uncontrolled growth of the grass carp population. The need to maintain a certain population of grass carp would require occasional restocking.

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. The grass carp are expected to grow to more than three feet.

Excessive milfoil in a lake tends inhibit other species and to damage its wildlife habitat. As of last year, about 28 acres of the 124-acre lake were infested with milfoil.