A recent scientific survey of Taunton Lake indicates that the lake’s infestation with milfoil, a pesky invasive aquatic plant native to Eurasia, has decreased by almost 90 percent when compared to the lake’s extensive infestation with the weed during 2015, according to George Benson, town planning director.

The plant also is known by the name Eurasian aquatic milfoil.

According to calculations by Kevin Dunkin, the town’s Geographic Information System (GIS) specialist, an August survey of the lake found that about 1.88 acres of the lake were infested with milfoil, as compared to 18.04 acres of infestation, which were recorded in a 2015 survey, representing an approximately 89 percent decrease in the infested area. Taunton Lake is a 126-acre spring-fed glacial lake located near Taunton Lake Road.

To show the change in weed infestation in the shallow waters of the lake near its shoreline, Mr Dunkin prepared an illustrated aerial photo of the lake that uses color coding to depict the decreased area of infestation.

Mr Benson said this week he believes that the presence of grass carp, a species of fish, in Taunton Lake have had a “significant effect” there in terms of reducing milfoil infestation. Sterile grass carp have been stocked in the lake in seeking to reduce the presence of milfoil. Grass carp eat milfoil. Mr Benson added that weather conditions also may have led to a reduction in the milfoil.

“It’s obviously a big change,” Mr Benson said of the 89 percent drop in milfoil coverage at Taunton Lake.

Mr Benson is a limnologist by training. Limnology is the study of lakes and other bodies of fresh water. Since milfoil was discovered in the lake in 2007, Mr Benson has advised the private Newtown Fish & Game Club and the private Taunton Lake Landowners Association on measures that could be taken to curb the weed’s spread.

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

Scientific research, which occurred at Taunton Lake after milfoil was first discovered in 2007, will continue, Mr Benson said. This fall, the state Department of Energy and Environmental Protection (DEEP) is slated to study the fish population of the lake through the elctro-shock method, in which fish which are temporarily stunned by electrical shocks and are then examined, after which they returned to the water. Next June, the state’s Agricultural Experiment Station plans to conduct another survey on milfoil infestation.

Such scientific study will help in determining whether more grass carp should be stocked in Taunton Lake for milfoil control, Mr Benson said.

In the past, when more milfoil was present, the weeds grew up to the water’s surface and floated there, he said. The tops of the milfoil plants detected in the recent survey had not grown upward far enough to reach the surface, remaining about one foot below the surface, on average.

On August 23, Mr Benson, Mr Dunkin, and Steve Maguire, the town’s senior land use enforcement officer, methodically toured the lake’s perimeter in a 12-foot Jon boat in recording the presence of the weed.

Milfoil spreads within a body of water by fragmentation. When broken into fragments, those fragments take root and grow upward from the lakebed.

Mr Benson estimated that water visibility in the lake ranges from about three to four feet. Milfoil, which requires sunlight to grow upward from a lakebed, grows more readily in water that is transparent rather than murky, he said.

Milfoil infestation of water bodies is a common problem in North America in lakes and waterways. Many lakes in the area have milfoil infestations, including Lake Zoar and Lake Lillinonah, both of which are impoundments on the Housatonic River. Candlewood Lake also is infested.

The infestations make water conditions irksome for swimmers, anglers, and boaters because the weeds tend to get tangled up on swimmers’ limbs, on fishing tackle, and on boat oars and propeller blades. Milfoil has long stems from which long needlelike leaflets radiate. It is transferred among lakes when fragments of the invasive weed cling to boats that are then placed in other lakes. About four acres of milfoil infestation in Taunton Lake were first noted in 2007 in the shallow waters at the southeastern end of the lake, near an old brick pump house. Milfoil was later discovered in the shallow-water southwestern section of the lake near a dam and also at the Newtown Fish & Game Club’s boat launch at the northwestern end of the lake.

In Taunton Lake, the deepest water in which milfoil is found is five to six feet deep. The lake’s deepest point is 29.5 feet. Milfoil will grow in the wintertime, provided that sunlight can penetrate transparent surface ice at the shallow areas of a lake.

Taunton Lake is ringed by private properties and has only limited public access. Only the southern side of the lake has dense residential development, with other lake sections being either lightly developed or undeveloped.