ACTON – A new infestation of invasive variable milfoil has been discovered in a lake that straddles the Maine-New Hampshire border, state officials said Monday.

Volunteers found the invasive species in Great East Lake, a 1,776-acre lake located in Acton and in Wakefield, N.H. The milfoil was found in New Hampshire waters just a few feet from a public boat ramp located in Maine.

It marks the first time in nearly two years that milfoil has been found in a Maine lake, said Paul Gregory, an environmental specialist with the Department of Environmental Protection.

The plant was spotted and pulled from the lake waters in July by a volunteer for the Great East Lake Improvement Association Weed Watcher Program. A DNA analysis at the University of Indiana this month confirmed that the plant was milfoil.

There have been no signs of additional milfoil in Great East Lake since the plant was pulled in July, but it won’t be known for sure until next spring if it was removed soon enough to prevent the spread of the plant.

Gregory said the discovery underscores the importance of volunteer groups that have monitored lakes and inspected boats since milfoil first became a problem a few years ago.

The Great East Lake group, for instance, has 60 volunteers who routinely monitor the lake’s 18 miles of shoreline.

“Once again citizen scientists have shown themselves to be the best first line of defense against invasive aquatic plant invasion,” Gregory said.

Invasive plant species have been found in 27 of Maine’s 5,700 lakes and ponds.