Curly leaf pondweed is an invasive nonnative plant that's infested ponds and lakes across North America.

NORTH ADAMS, Mass. — Windsor Lake will be closed Thursday and Friday for herbicide to be applied to invasive species in the lake.

The treatment along areas near the shoreline with an aquatic herbicide registered with the state and the U.S. Environmental Protection Agency will target non-native curly leaf pondweed.

The entire lake will be closed to all water uses (including swimming, fishing and boating) on those two days of treatment. The lake shoreline will be posted with printed signs warning of these restrictions, in advance of treatment.

Pets or wildlife that may drink the lake water will not be harmed. These water uses will resume on Saturday morning, June 25.

The treatment is part of the city's five-year Windsor Lake Management Plan. The plan was instituted last year to largely to deal with the explosive growth of invasive phragmites, tall grassy plants that had taken over large areas of the shallows. The treatments that began last year have very visibly reduced the coverage of the plants that formerly blocked the view of the campground beach from the public areas.

The curly leaf pondweed has also made inroads at Fish Pond. The hardy, aggressive plant emerges in spring and dies back by June or July and can grow in water up to 15 feet deep. It is a native to Africa, Australia and Eurasia.

The plant has spread rapidly throughout North America largely because of fisheries and hatcheries using the plant as source of food and habitat for their fish. Curly-leaf pondweed is characterized by lasagna-like leaves, which are stiff and semitransparent with serrated edges. The leaves are arranged alternating up the stem with increasing frequency as they approach the tip. Only a flower stalk emerges above the water; the rest of the plant grows beneath the surface of the water.