Lake George Watershed -- 02010001

Watershed Name: Lake George
USGS Cataloging Unit: 02010001
VT 0th Congressional District
NY 20th Congressional District
NY 23th Congressional District


Aquatic Invasive Species in EPA Region 2

Several unwelcome aquatic invasive species have made their way into New York and New Jersey waters and many more are knocking at the door. Aquatic invasive plants like Eurasian watermilfoil, hydrilla, didymo (rock snot) and water chestnut choke once thriving waterways. Invasive fish species such as the snakehead, flathead catfish, and Asian swamp eel can outcompete other fish, including rarely encountered native species and prized recreational fish, for food and available habitat. Zebra mussels choke intake pipes and cover critical spawning substrate. Many of the same mechanisms which transport invasive plants and animals also transmit diseases such as Viral Hemorrhagic Septicemia (VHS), Infectious Pancreatic Necrosis Virus (IPN) and Largemouth Bass Virus (LMBV) which threaten fish populations.

Why are invasive species a problem?
Invasive species are defined as "a species that is non-native to an ecosystem and whose introduction causes or is likely to cause harm be it economic, environmental or to human health."

  • Predation: Large snakeheads and flatheads indiscriminately consume any fish species small enough to fit into their enormous mouths.
  • Competition: Food, spawning areas and habitat are sought by invasive fish, leaving less available for desirable species.
    Habitat Loss: Plants like purple loosestrife or common reed (phragmites) can take over a wetland making it less suitable for native wildlife.
  • Loss of Recreation: Bighead and silver carp threaten recreational boating as these large fish, when startled, leap out of the water high enough to intercept passing boaters.
  • Decreased Property Value: Beautiful lakefront property can be transformed into a weed-choked monoculture once Eurasian watermilfoil or water chestnut become established.
    Economic Impact: Zebra mussels cause millions of dollars of damage each year in the Great Lakes alone.

Potentially Dangerous Fish Species

New Jersey statutes prohibit the possession or release of live, potentially dangerous animals including fish. Dangerous species are defined as "a species that is non-native to an ecosystem and whose introduction causes, or is likely to cause, economic or environmental harm or harm to human health." The Fish Code identified ten such species (see below). These fish are considered to possess the potential for becoming a significant threat to indigenous animals, the environment, or public safety. Possession and/or release of live potentially dangerous fish species is prohibited and if these species are encountered while angling they must be destroyed. 

Common Carp
Common Carp

Although common carp are considered an invasive species by most, they are not designated as a potentially dangerous fish species, in part because of how widespread they have become. The stocking of common carp is prohibited, in an effort to minimize their establishment into new waters.

Snakeheads and flathead catfish are top-level predators and may negatively impact the structure of indigenous and established fish populations. Bighead carp and silver carp threaten human health as they leap out of the water when startled and may intercept passing boaters. When unregulated, grass carp are an invasive species that can over-graze aquatic vegetation, thus destroying fish habitat. Green sunfish and warmouths have a larger mouth than the state's native sunfish, thus have the ability to outcompete native fish. Asian swamp eel, brook stickleback, and oriental weatherfish are highly tolerant, generalist feeders that compete with native fish.


New York and New Jersey list three carp species as potentially dangerous fish species among their invasive species:


Invasive Bighead Carp

Hypophthalmichthys nobolis


Invasive Grass Carp

Ctenopharyngodon idella


Invasive Silver Carp

Hypophthalmichthys molitrix


Brook Stickleback

Culaea inconstans


Green Sunfish

Lepomis cyanellus

ASIAN SWAMP EEL - Monopterus albus

American eels are a diadromous native species, using both fresh and marine water during their lifecycle.

Invasive Alert - Asian Swamp Eel (pdf, 68kb) by Christopher Smith, Principal Biologist, 2009 Freshwater Fishing Digest 
Asian Swamp Eel Management Activities: 2010


FLATHEAD CATFISH - Pylodictis olivaris

The flathead catfish is considered an invasive species capable of causing ecological damage by out-competing other recreationally important species for food and habitat. Although not a native species, channel catfish are stocked by Fish and Wildlife in select locations as it is a desirable recreational and food species. They do not reproduce in most waters, and in the few where they do, populations do not reach problematic proportions.

SNAKEHEAD - Channa spp.

Bowfin is a native species, actually dating back 250 million years and should be released unharmed. However, snakeheads are invasive and should be destroyed and submitted to the Division of Fish and Wildlife for verification.

Snakehead Management Activities 2010 (pdf, 11kb)



The introduction of invasive aquatic plants not only affects the waterbody ecology but negatively affects the local economy of a lake community. Before leaving any body of water all aquatic plants should be removed from boats, motors, and trailers.

Water Chestnut Management Activities: 2010 (pdf, 8kb)


How to Identify Zebra Mussels

Look like small clams with a yellowish or brownish "D"-shaped shell, usually with alternating dark and light colored stripes.

  • Up to two inches long, but most are under an inch.
  • Usually grow in clusters
  • Zebra mussels are the ONLY freshwater mollusk that can firmly attach itself to solid objects-rocks, dock pilings, boat hulls, water intake pipes, etc.