Eurasian Watermilfoil

Cutting Back on Invasive Species


As part of a coalition of organizations, the Lake George Association is working to remove milfoil from Lake George, investing tens of thousands of dollars each year to hand-harvest the plants or use diver assisted suction harvesting and reduce in the invasive species' footprint. Additionally, we swim through and survey milfoil sites in Lake George multiple times each summer to ensure the removal process is effective after our contractor has stopped working in an area.

But it is not an easy job. Because the plant self-fragments, pieces of milfoil from patches break off and re-root nearby, confounding efforts to completely eradicate it. The invasive aquatic plant is in more than 200 locations in Lake George's 32 mile length. Several methods to control milfoil in Lake George have been used, including hand harvesting and matting.

See the 2018 Comprehensive report of milfoil management operations on Lake George - pdf.

What is Eurasian watermilfoil?

Eurasian watermilfoil (Myriophyllum spicatum) is an invasive aquatic plant native to Europe, Asia and North Africa. It was first documented in North America in 1942 in the District of Columbia. It was most likely brought to this continent in the ballast of a ship and has since spread to almost every continental state and throughout Canada.

Why is it a problem?

Eurasian watermilfoil spreads easily and grows quickly. Eurasian watermilfoil crowds out native plants, reducing biodiversity, diminishes fish habitat and negatively impacts wetland habitats. Dense mats form near the surface.  They entangle boat propellers and interfere with swimming and fishing.  As a result, Eurasian watermilfoil can adversely affect our local tourist-dependent economy.

What does Eurasian watermilfoil look like?

Eurasian watermilfoil resembles the native Northern Watermilfoil (Myriophyllum sibiricum).Unlike the Eurasian variety, Northern milfoil offers shade, shelter and foraging opportunities for fish. There are several distinguishing characteristics that can be used to differentiate between the two species; please see graphic for the details.

closeup of Eurasian milfoil in water

Image Credit Alison Fox, University of Florida,

Eurasian Milfoil takes over a pond

Image credit: Leslie J. Mehrhoff, UConn,

Invasive Eurasian Watermilfoil

Invasive Eurasian Watermilfoil
  • Usually 12-21 leaflet pairs per leaf
  • Delicate, feather-like leaves
  • Leaflets are mostly the same length
  • Leaves arranged in whorls (circles) of three to five around each stem
  • Leaves are limp when out of water
  • Stem is as thick or thicker than a pencil and is long and spaghetti-like

Native Northern Watermilfoil

Native Northern Milfoil
  • Usually 7-10 leaflet pairs per stem
  • Rigid feather-like leaves form a Christmas tree shape
  • Lower leaflets are usually quite long
  • Leaves arranged in whorls (circles) of four to six around stem
  • Leaves are usually rigid when out of water
  • Stem is usually whitish, or whitish-green in color

Click here to print out the LGA "Good vs. Bad" Milfoil card - pdf. Click here for a Milfoil Look-a-Likes fact sheet - pdf that includes additional look-a-like species.

What should you do if you find Eurasian Watermilfoil in Lake George?

Leave it alone. As a homeowner you can carefully remove plants immediately around the area of your dock. (Read more details in the Adirondack Park Agency's Advice for Hand Harvesting - pdf) You need to know how to properly remove it, though, because if you break the plant up you will just create more plants and do more harm than good.

Eurasian Watermilfoil reproduces through vegetative propagation, so each tiny bit that floats off can form a new plant. If you find an area of Eurasian watermilfoil contact us.  Alternatively, you can check the milfoil location maps to see if the Lake George Park Commission knows about the bed.

Where is it located in Lake George?

As noted above, the 2016 Report explains that a total of 216 Eurasian watermilfoil sites have been identified. In the southern basin, there are high concentrations of milfoil sites near human population centers and boat-use areas including, but not limited to Lake George Village, Bolton Landing, Harris Bay, Warner Bay, Dunham's Bay, Huddle Bay and off of Long Island. In the north basin, clusters of Eurasian watermilfoil sites are also found in areas of high use near Huletts Landing, Putnam, Hague, and Roger’s Rock

A total 186,590 pounds -- or about 93 tons -- of Eurasian watermilfoil was harvested in 2020.

Management activities in Lake George continue to have a positive impact on the control of many milfoil sites.

How does Eurasian watermilfoil spread?

The primary way Eurasian watermilfoil spreads is through vegetative reproduction. This spread is mainly through fragmentation of plant tips or through root expansion. With fragmentation, even a very small piece of this aquatic plant can float away, re-root and begin a new colony. It is easily fragmented and moved around within lakes by boats, or between lakes on boats and trailers. Eurasian watermilfoil milfoil can form thick, floating mats of vegetation, clogging the water and hindering recreation. It can grow in water 0.5 -10 meters deep.