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Aquatic Nuisance Species
Aquatic Nuisance Species
Dirty Boat

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​ANS ALERT: Monitoring finds Evidence of Quagga Mussel Larvae in Green Mountain Reservoir

State and federal officials have confirmed the presence of invasive quagga mussel larvae, known as veligers, in Green Mountain Reservoir​.

On Aug. 18, as part of a state and federal initiative to monitor aquatic nuisance species (ANS) in the state, specialists with the U.S. Bureau of Reclamation first confirmed the presence of the veligers, initially through microscopic analysis followed by DNA testing. An independent laboratory contracted by Colorado Parks and Wildlife confirmed Reclamation's findings. It is unknown if the veligers were dead or alive at the time of detection. 

To learn more about how this will impact boaters, please visit the boating inspection page.


Listen to the Story: Aquatic Nuisance Species​

Aquatic nuisance species can wreak havoc on ecosystems, outdoor recreation, hydroelectric power equipment and the economy. When dreaded mussel larvae were discovered  at Green Mountain Reservoir in August, state leaders sent a plea for help all the way to the White House. As part of the Connecting the Drops series, KGNU's Hannah Leigh Myers joined a Colorado Parks and Wildlife team as they took samples at Green Mountain Reservoir in an effort to ward off the invasive mussels and keep Colorado waters safe from threatening species​.

Listen to the interview on yourwatercolorado.org​.​​

​​​​​​​Aquatic Nuisance Species (ANS)

Aquatic Nuisance Species (ANS) are aquatic plants and animals that invade lakes, reservoirs, rivers and streams. Examples of ANS include:

  • ​​Zebra mussel
  • Quagga mussel
  • New Zealand mudsnail
  • Asian carp
  • Rusty crayfish
  • Eurasian watermilfoil. 
​ANS can also include fish pathogens and diseases, such as viral hemorrhagic septicemia (VHS) or whirling disease. ​

Top concerns:

Zebra Mussels

Zebra and Quagga Mussels
Zebra mussels are native to the Black, Caspian and Azov Seas of Eastern Europe.  They were discovered in the Great Lakes in Lake St. Clair in 1988 and have since spread to 33 states in the United States. >> Learn more.​
New Zealand Mudsnails

New Zealand Mudsnails
New Zealand mudsnails are an invasive freshwater snail. They are voracious eaters that reproduce rapidly, eating much of the available food.  >> Learn more.​​
Rusty CrayfishRusty Crayfish
Rusty crayfish are a larger, aggressive freshwater crayfish, native to the Ohio River Basin. The rusty patches on either side of their body can sometimes identify them.​ >> Learn more​.​​
​WaterfleaWaterflea
Waterfleas are zooplankton aquatic crustaceans that have a jumpy or jerky mode of swimming. They are often identified by their long tails, up to 70% of total body length.​ >> Learn more.​​


ANS Program Legislative Declaration:

The General Assembly hereby recognizes the devastating eco​nomic, environmental and social impacts of aquatic nuisance species on the aquatic resources and water infrastructure of the state. The General Assembly further recognizes the potential of recreational vessels to be a significant source of the spread of aquatic nuisance species in Colorado. Therefore, the General Assembly finds, determines and declares that the purposes of enacting this article are to implement actions to detect, prevent, contain, control, monitor, and, whenever possible, eradicate aquatic nuisance species from waters of the state and to protect human health, safety and welfare from aquatic nuisance species. It is the intent of the general assembly to foster and encourage t​​​o the greatest extent possible voluntary compliance with this article. It is the intent of the general assembly that prevention, containment and eradiation of aquatic nuisance species have been detected or are likely to be introduced shall be the Divisions' highest priorities.