Invasive Species

What are Invasive Species?

Invasive Species are non-native animals, fish, plants and pathogens that have a harmful effect on our natural resources and the human use of those resources. Aquatic invasive species are commonly called Aquatic Nuisance Species (ANS) and were defined in 2008 by the State Legislature as any exotic or nonnative wildlife or any plant species that have been determined by the board to pose a significant threat to the aquatic resources or water infrastructure of the state. The Colorado Division of Wildlife is the lead agency on ANS statewide.

What are the ANS that Colorado is concerned about?

The Colorado Division of Wildlife has been monitoring the state’s waters for the introduction of ANS since 2005. Currently over 160 lakes and reservoirs, in addition to many rivers and streams, are being monitored. However, very few ANS are known to exist in Colorado. The ANS that Colorado are concerned about includes, but is not limited to, the list below:

Animals: (read more)
Crab, Mitten
Crayfish, rusty*
Frog, Green
Mussel, quagga*
Mussel, zebra*
New Zealand mudsnail*
Eriocheir (all species)
Orconectes rusticus
Rana clamitans
Dreissena bugensis
Dreissena polymorpha
Potamopyrgus antipodarum
Daphnia lumholtzii
Cercopagis pengoi
Bythotrephes longimanus (also known as Bythotrephes cederstroemi)

Fish: (read more)
Bowfin Amia calva
Carp All Species in the Genus' Aristichthys, Catla, Catlocarpio, Carrassius, Cirrhinus, Cyprinus, Hypophthalmichtys, Labeo, Mylopharyngodon, Tor
Hybrid Grass Carp
Catfish, walking
Asian swamp eel
Perch, White
Ruffe, Eurasian
Snakeheads and Murrels
Ctenopharyngodon idella x Aristichthys nobilis
Clarias batrachus
Monopterus albus
All species in the family Lepisosteidae
All species in the family Gobiidae
Morone Americana
Gymnocephalis cernuus
All species of the Genus' Serrasalmus and Pygocentrus
Scardinius erthrophthalmus
All species in the Genus' Channa, Parachanna, Ophicephalus, Bostrychoides, Ophiocephalus, Parophiocephalus
All species in the Genus' Apeltes, Gasterosteus, Pungitius, Culaea, Spinachia, Aulorhynchus
All species in the Genus' Tilapia, Oreochromis, Sarotherodon
Hoplias malabaricus

Didymo "Rock Snot" Didymosphenia geminate

Plants: (read more)
African elodea
Brazilian elodea
Eurasian watermilfoil*
Giant salvinia
Hyacinth, water*
Yellow floating heart
Purple loosestrife*
Lagarosiphon major
Egeria densa
Myriophyllum spicatum
Salvinia molesta
Eichornia crassipes
Hydrilla verticillata
Myriophyllum aquaticum
Nymphoides peltata
Lythrum salicaria

Pathogens: (read more)
Whirling Disease*
Viral Hemorrhagic Septicemia
Myxobolus cerbralis

*Species is known to Colorado.

Ecological Impacts

The introduction of Nonindigenous or non-native aquatic species into an established ecosystem can alter or disrupt existing relationships and ecological processes. Without natural predators, ANS out-compete and even displace native species by outcompeting them for light, nutrients and space. The most destructive ANS, the zebra and quagga mussels, attaches into the intake pipes of hundreds of facilities that use raw water, resulting in extensive monitoring and control costs. The U.S. Fish and Wildlife Service estimates the potential economic impact at $5 billion over the next ten years to U.S. and Canadian factories, water suppliers, power plants, ships and fisheries within the Great Lakes region. For example, the Consumers Energy Company currently spends nearly $1 million annually to control the zebra mussel.

How you can stop the spread of ANS:

CLEAN: Remove all plants, mud and animals from your boat, trailer, truck and other boating equipment (anchors, centerboards, rollers, axles, propellers, etc.) before leaving any water body. Be sure not to move plants, mud or any animals on waders or other fishing equipment. Biologists and Researchers must also take extra caution not to move plants, mud and animals on gear or equipment while working in the field by keeping all equipment clean and dry in between each use. Even moving an organism from one stretch of a river to another part of the same river can cause irreversible consequences for the ecosystem.

Clean your boat, gear and equipment that normally get wet with hot water (minimum temperature is 40°C or 140°F) and fully dry your boat and equipment in between each and every use to be sure that all organisms are killed and removed from the vessel. Adult zebra and quagga mussels are killed at 140°F on contact and other species are killed between 100-140°F.

DRAIN water from the motor, live well, bait well, bilge, ballast tanks, bladders and transom wells at the ramp or access before leaving any water body. Be sure your boat, including all compartments and equipment are fully dry in between each use and never move water from one water body to another.

DRY your boat and other boating equipment to kill harmful exotic animal species that were not visible at the boat launch. Be sure your vessel including all compartments are fully drained and dried in between each and every use.

LIVE BAIT: If you are fishing with live bait, be sure to empty your bait bucket in the garbage before leaving any water body. Never release live bait into a water body, or release aquatic animals from one water body into another.

AQUARIUM OWNERS & POND GARDENERS: Never release unwanted aquarium or backyard pond pets or plants into the wild. Many invasive species are escaped ornamental species or pets that were no longer wanted and were introduced into the wild. If you have animals or plants you no longer want, please dispose of them in the garbage or take them to your nearest Division of Wildlife office.


Since 2008, Colorado has implemented a mandatory state-certified boat inspection program to help prevent the spread of zebra and quagga mussels and other ANS in Colorado lakes, reservoirs, streams and rivers. Boaters, anglers and scientists should be clean, drained and dry in between each time they launch their boat or put their equipment into the water.

Resident Boaters must pass a state-certified boat inspection if:

  • You have traveled outside of the state to boat.
  • If you have launched on any of the Colorado lakes or reservoirs where mussels have been detected. You must submit to an inspection for aquatic nuisance species prior to leaving the body of water.
  • You enter a reservoir where inspections are required. Roving Patrols will randomly staff reservoirs where permanent inspection stations aren't currently in place. Boaters should expect to be inspected at any lake or reservoir in the state.

Out-of-State Boaters must pass a state-certified boat inspection if you plan on launching in any Colorado lake, reservoir or waterway.

Report any suspect or known ANS populations:

Timely and accurate identification is very important in dealing with invasive species. To help the Colorado Division of Wildlife quickly identify new populations of this unwanted species or to obtain more information about invasive species, please contact Elizabeth Brown, State Invasive Species Coordinator at 303-291-7362 or