The Vermont Department of Environmental Conservation says adult zebra mussels have been found in Lake Dunmore in Leicester.
The state tested the specimens after an inquiry from the Lake Dunmore Public Access Greeter Program.
The Lake Dunmore lake association then contracted divers who removed an estimated 100 to 200 specimens.
The state is now developing a plan to contain the mussels and prevent their further spread.
The mussels were found next to a Vermont Fish and Wildlife Public Access Area, highlighting the need for boaters to check and clean boats to prevent the spread of aquatic invasive species.
Zebra mussels are a small freshwater mollusk first found in Lake Champlain in 1993. They reproduce rapidly and cause serious harm to the ecological systems.