Aquatic Nuisance Species
Invasive Wildlife
Aquatic Nuisance Species
Aquatic Nuisance Species are aquatic plants and animals that invade lakes, reservoirs, rivers and streams. The invasive species can also include fish pathogens and diseases.
Threats to Colorado
Zebra and Quagga Mussels
Zebra and quagga mussels are not native to the nation’s rivers, lakes and reservoirs and are considered our most serious threat. They cause enormous problems for water infrastructure used for municipal, agriculture and industrial purposes by attaching to, clogging and impairing water storage, treatment and distribution systems.
New Zealand Mudsnails
New Zealand mudsnails are an invasive freshwater snail. They are voracious eaters that reproduce rapidly, eating much of the available food. This negatively affects aquatic insect larvae, native snails, as well as fish populations. They are able to pass through a fish's digestive system unharmed, leaving the fish malnourished.
Rusty Crayfish
Rusty crayfish are a larger, more aggressive freshwater crayfish, native to the Ohio River Basin. The rusty patches on either side of their body can sometimes identify them. They are believed to have been introduced to Colorado by anglers as bait. These crayfish will eat small fish, aquatic insects, eggs and even aquatic vegetation, damaging underwater habitat that is important for fish spawning, cover and food. They also outcompete and displace native crayfish.
Waterflea
Fishhook Water Fleas are small aquatic crustaceans that have a jumpy or jerky mode of swimming. There are two other species prohibited in Colorado. They are spiny waterflea (Bythotrephes longimanus) and fishhook waterflea (Ceropagis pengoi).Unlike the fleas dogs are known to carry, waterfleas are very different. They do not live outside the water, and do not bite or harm people or pets.
Infected Waters in Colorado
South Platte River (just below Eleven Mile dam in Park County)
Positive since 2004
Boulder Creek
Positive since 2004
Green River within Dinosaur National Monument
Positive since 2005
Dry Creek, City of Boulder
South Delaney Buttes State Wildlife Area
Positive since 2010
East Delaney Buttes State Wildlife Area
Positive since 2010
Eleven Mile Reservoir State Park
Positive since 2011
Charlie Meyer State Wildlife Area
Positive since 2011
College Lake, Colorado State University
Positive since 2011
Spinney Mountain State Park
Positive since 2011
Fountain Creek
Positive since 2012
Chatfield Reservoir
Positive since 2013
Gunnison River (West of Delta)
Positive since 2015
Fourmile Canyon Creek (Boulder County)
Positive since 2016
Monument Lake
Positive since 2017
South Platte River (Near Deckers)
Positive since 2017
Uncompahgre River (Town of Montrose)
Positive since 2017
Jimmy Camp Creek
Positive since 2017
Monument Reservoir
Positive since 2018
Trinidad Lake
Positive since 2018
Lake Capote
Positive since 2018
Chatfield Pond #1
Positive since 2019
Elmer’s 2 Mile Park (Boulder County)
Positive since 2019
South Platte River (City of Denver)
Positive since 2019
Trout Creek
Positive since 2020
South Boulder Creek
Positive since 2020
Antero Reservoir
Positive Since 2024
South Platte River (just below Eleven Mile dam in Park County)
Positive since 2004
Boulder Creek
Positive since 2004
Green River within Dinosaur National Monument
Positive since 2005
Dry Creek, City of Boulder
South Delaney Buttes State Wildlife Area
Positive since 2010
East Delaney Buttes State Wildlife Area
Positive since 2010
Eleven Mile Reservoir State Park
Positive since 2011
Charlie Meyer State Wildlife Area
Positive since 2011
College Lake, Colorado State University
Positive since 2011
Spinney Mountain State Park
Positive since 2011
Fountain Creek
Positive since 2012
Chatfield Reservoir
Positive since 2013
Gunnison River (West of Delta)
Positive since 2015
Fourmile Canyon Creek (Boulder County)
Positive since 2016
Monument Lake
Positive since 2017
South Platte River (Near Deckers)
Positive since 2017
Uncompahgre River (Town of Montrose)
Positive since 2017
Jimmy Camp Creek
Positive since 2017
Monument Reservoir
Positive since 2018
Trinidad Lake
Positive since 2018
Lake Capote
Positive since 2018
Chatfield Pond #1
Positive since 2019
Elmer’s 2 Mile Park (Boulder County)
Positive since 2019
South Platte River (City of Denver)
Positive since 2019
Trout Creek
Positive since 2020
South Boulder Creek
Positive since 2020
Antero Reservoir
Positive Since 2024
Yampa River
Positive since 2009
Catamount Reservoir
Positive since 2009
Sanchez State Wildlife Area
Positive since 2010
Stagecoach Reservoir State Park
Positive since 2011
Yampa River
Positive since 2009
Catamount Reservoir
Positive since 2009
Sanchez State Wildlife Area
Positive since 2010
Stagecoach Reservoir State Park
Positive since 2011
Adobe Creek Reservoir
Daphnia lumholtzi
Arkansas River (below Pueblo Dam)
Daphnia lumholtzi
Barr Lake
Daphnia lumholtzi
Bear Creek Reservoir
Daphnia lumholtzi
Boedecker Reservoir
Daphnia lumholtzi
Boulder Reservoir
Daphnia lumholtzi
Boxelder Lake #3/Smith Lake
Daphnia lumholtzi
Boyd Lake
Daphnia lumholtzi
Chatfield Reservoir
Daphnia lumholtzi
Cherry Creek Reservoir
Daphnia lumholtzi
Douglas Reservoir
Daphnia lumholtzi
Holbrook Reservoir
Daphnia lumholtzi
Horsetooth Reservoir
Daphnia lumholtzi
Jackson Reservoir
Daphnia lumholtzi
John Martin Reservoir
Daphnia lumholtzi
Jumbo Reservoir
Daphnia lumholtzi
Navajo Reservoir
Daphnia lumholtzi
North Sterling Reservoir
Daphnia lumholtzi
Prewitt Reservoir
Daphnia lumholtzi
Prospect Lake
Daphnia lumholtzi
Pueblo Hatchery
Daphnia lumholtzi
Pueblo Reservoir
Daphnia lumholtzi
Union Reservoir
Daphnia lumholtzi
Windsor Reservoir
Daphnia lumholtzi
Adobe Creek Reservoir
Daphnia lumholtzi
Arkansas River (below Pueblo Dam)
Daphnia lumholtzi
Barr Lake
Daphnia lumholtzi
Bear Creek Reservoir
Daphnia lumholtzi
Boedecker Reservoir
Daphnia lumholtzi
Boulder Reservoir
Daphnia lumholtzi
Boxelder Lake #3/Smith Lake
Daphnia lumholtzi
Boyd Lake
Daphnia lumholtzi
Chatfield Reservoir
Daphnia lumholtzi
Cherry Creek Reservoir
Daphnia lumholtzi
Douglas Reservoir
Daphnia lumholtzi
Holbrook Reservoir
Daphnia lumholtzi
Horsetooth Reservoir
Daphnia lumholtzi
Jackson Reservoir
Daphnia lumholtzi
John Martin Reservoir
Daphnia lumholtzi
Jumbo Reservoir
Daphnia lumholtzi
Navajo Reservoir
Daphnia lumholtzi
North Sterling Reservoir
Daphnia lumholtzi
Prewitt Reservoir
Daphnia lumholtzi
Prospect Lake
Daphnia lumholtzi
Pueblo Hatchery
Daphnia lumholtzi
Pueblo Reservoir
Daphnia lumholtzi
Union Reservoir
Daphnia lumholtzi
Windsor Reservoir
Daphnia lumholtzi
Highline Lake and the Colorado River (in Grand Junction) have tested positive for zebra mussels.
Out of State
Colorado is experiencing a significant increase in the amount of mussel boats being intercepted at lakes and reservoirs across the state. While these boats are coming in from all directions, the majority are originating from Lake Powell (72%).
Invasion of mussels from out-of-state waters continues to be a threat, and will likely increase. Almost all states to the east of Colorado have a zebra or quagga mussel infestation. The closest is Cedar Bluff Reservoir which is only 150 miles from our border in Kansas. The southwest US has many widespread infestations including Lake Powell, Lake Mead, Lake Mohave, and Lake Havasu, which are all frequented by Colorado boaters.
Water Education Colorado
Aquatic nuisance species 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.
Listen to the Story
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.
Find out more