Current Invaders

There are currently 6 known invasive species in Lake George.  They are Eurasian watermilfoil, curly-leaf pondweed, zebra mussels, Asian clam, Chinese mystery snail and spiny water flea.  Brittle naiad and water chestnut have been found in the lake in the past, but were removed, and no current known populations of these plants remain.

Eurasian Watermilfoil
Curly-leaf Pondweed
Zebra Mussels
Asian Clam
Spiny Water Flea
Chinese Mystery Snail

Eurasian watermilfoil

Eurasian watermilfoil in Lake George. photo courtesy LGA


Eurasian Watermilfoil (Myriophyllum spicatum)

  • Submersed, aquatic plant with leaves divided into many leaflets, giving a feathery appearance.
  • Grows in up to 20 feet of water, forming dense mats in areas of water 15 feet or less.
  • Forms dense mats that crowd out native plants, affect food web structure, hinder recreation, and can even decrease property values



Current Status:
First found in Lake George is 1985; managed since 1986. EWM has been managed in Lake George for many years with benthic barriers and hand harvesting. High concentrations of milfoil sites still remain near human population centers and boat-use areas in the Lake.

EWM management

Divers harvesting Eurasian watermilfoil in LG. photo courtesy Rich King, Lycott Environmental

During 2011, Lycott Environmental was contracted by the Lake George Park Commission for EWM management activities, and Aquatic Invasives Management (AIM) was contracted by the Fund for Lake George for EWM management activities.

Summary of Lycott Management Activities
By the conclusion of the 2013 management effort, a total of 203 Eurasian Watermilfoil sites were identified.Of the 204 known milfoil sites, 203 have been managed for milfoil in one or more years since the start of aquatic plant management efforts. Of these, 101 were cleared of milfoil in 2013 by Lycott and an additional 74 sites remained clear of milfoil from prior efforts. Thus, at the close of the 2013 effort, 175 of the 203 sites were cleared of milfoil growth. Further, five sites were controlled but not cleared resulting in 180 total controlled sites in Lake George.

Click here for the entire 2013 Report prepared for the Lake George Park Commission by Lycott Environmental.

Click here for a pdf of a presentation by Rich King of Lycott Environmental on ‘Long-­Term Strategic Management of Eurasian Watermilfoil in Lake George: a 20-year perspective’.

Summary of AIM Management Activities
Click here to see interactive maps of AIM’s EWM harvesting activites in LG in 2010 and 2011.

curly-leaf pondweed

curly-leaf pondweed in LG. photo courtesy LGA

Curly-leaf Pondweed (Potamogeton crispus)

  • Submersed, aquatic plant with spaghetti-like stems that can often reach the surface by mid-June
  • Lasagna-like leaves are serrated on edges
  • Grows in up to 12 feet of water and can tolerate low light conditions
  • Die offs in early summer can lead to oxygen depletion in shallow water
  • Not currently managed in Lake George



Zebra Mussels (Dreissena polymorpha)

zebra mussels. photo courtesy LGA

  • Small bi-valves native to Eurasia that are triangular in shape and have striped shells.
  • Up to two inches long, but most are under one inch in length
  • Attach to hard surfaces with byssal thread, fouling boat hulls and dock posts and clogging water pipes.
  • Sharp shells cover rocks and litter beaches.
  • A single mussel can filter up to 1 quart of water per day; drastically altering the food web.


Current Status: Microscopic veligers first detected in Lake George in 1995. Adults first found at single site in Lake George Village on Dec 18, 1999.  Over 19,000 individual mussels were hand harvest from the site in 2000.

Another 9 sites have been found since the first site, bringing the total to 10 known locations of zebra mussels in the lake. However, the first site was the largest infestation by far. As of the end of 2009, over 25,000 adult zebra mussels have been removed from the lake.  Due to low lake-wide calcium levels, zebra mussel reproduction appears to be inhibited, so far sparing Lake George from being overrun by this invader.

graphic courtesy LGA


Asian clams. photo courtesy LGA.

Asian Clam (Corbicula fluminea)

  • small, rounded bivalves about the size of a dime
  • golden or brown in color
  • often found in shallow, calm, warm water with a sandy bottom
  • outcompete native mollusks
  • increase nutrients in water; facilitating algal growth
  • microscopic larvae can be transported in water
  • To learn more about Asian clams in Lake George, go to

spiny water fleas from LG. photo courtesy Emily DeBolt

Spiny Water Flea (Bythotrephes longimanus)

  • tiny crustacean zooplankton
  • 1/4-1/2″ long overall with long, barbed tail
  • tail is 70% of total body length
  • predate on other zooplankton; compete with juvenile fish for food
  • impact plankton community structure
  • no known management
  • resting eggs overwinter in lake bottom sediments
  • collect in masses on fishing line

Click here for a fact sheet about spiny water flea in Lake George.

spiny water fleas from Lake George on fishing line. photo courtesy Emily DeBolt

Chinese Mystery Snail

Chinese Mystery Snail was found in Lake George in August 2011 during the lake-wide survey for Asian clam. The snails were found in Middleworth Bay, on the southwest side of the Lake.

Click here to learn more about the Chinese Mystery Snail.