There are currently 6 known invasive species in Lake George:
A submersed aquatic plant with leaves divided into many leaflets, giving a feathery appearance. Eurasian watermilfoil grows in up to 20 feet of water, forming dense mats in areas of water 15 feet or less. These dense mats crowd out native plants, affect food web structure, hinder recreation, and can even decrease property values.
First found in Lake George in 1985, Eurasian watermilfoil has been managed since 1986 using benthic barriers and hand harvesting. High concentrations still remain near human population centers and boat-use areas in the Lake.
A submersed aquatic plant with spaghetti-like stems and lasagna-like leaves that are serrated on the edges. Curly-leaf pondweed grows in up to 12 feet of water, is very tolerant of low-light conditions, and can often reach the surface by mid-June. With a die-off in early summer, oxygen depletion in shallow water can occur.
Curly-leaf pondweed is not currently managed in Lake George.
A small bi-valve that is native to Eurasia. Zebra mussels are triangular in shape and can measure up to two inches long, though most are under one inch. Their striped, sharp shells cover rocks and litter beaches, as well as attaching to hard surfaces with byssal thread, fouling boat hulls and dock posts and clogging water pipes. A single mussel can filter up to 1 quart of water per day, drastically altering the food web.
Microscopic veligers were first detected in 1995, with the first infestation of adults being found in Lake George Village in 1999. Since then another 9 sites have been found, all less significant than the first infestation. To date, 25,000 adult zebra mussels have been removed. Due to low lake-wide calcium levels, reproduction appears to be inhibited, so far sparing Lake George from being overrun by this invader.
A small, rounded bi-valve approximately the size of a dime and golden or brown in color. Asian clams are often found in shallow, calm, warm water with a sandy bottom. They outcompete native mollusks and increase nutrients in the water, facilitating algal growth. Microscopic Asian clam larvae can be transported in water.
The total number of Asian clam sites is 24 throughout the lake, mostly in the southern basin on the more developed western shoreline, which has many sandy areas. The most recent Asian clan control/eradication effort was in 2015 at Rogers Rock campground in the Town of Hague. At this time, there have not been any significant recreational or environmental impacts from this species in Lake George, although populations have been expanding throughout the lake and the future remains unclear.
Spiny Water Flea
A tiny crustacean zooplankton measuring 1/4-1/2” long, including a long, barbed tail that makes up 70% of the total length. Spiny water fleas compete with juvenile fish for food and impact the plankton community structure. Over winter, eggs rest in lake bottom sediments, and after hatching, collect in masses on fishing line.
There is no known management for spiny water flea.
Chinese Mystery Snail
Cipangopaludina chinensis malleata
Called “mystery” snails because in spring, they give birth to young, fully developed snails that suddenly and mysteriously appear. Adult snails are more than 1.5 inches in length and vary in color from olive green to brown to reddish brown. The shell has 6 to 7 whorls and no banding, and an operculum (trapdoor) seals off the snail from adverse water conditions.
Chinese Mystery Snails achieve very high densities and adversely affect aquatic food webs by competing with native snails for food and habitat, which may contribute to their decline. They may also transmit parasites and diseases. This species also clogs screens on any size water-intake pipe, making them an economic nuisance in addition to an ecological threat.
Chinese mystery snails were found in 2011 in Middleworth Bay (on the southwest side of the Lake) during the lake-wide survey for Asian clam.
For more details on invasives in Lake George and the threat, visit the LGA’s website.