What are 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 effects aquatic insect larvae, native snails, as well as fish populations. Humans inadvertently move NZMS from one stream to another when they cling to waders, boots, boats, dogs and other gear. They can reproduce sexually or asexually, so just one snail can start an entirely new population! They are also able to pass through a fish's digestive system unharmed, leaving the fish malnourished.
New Zealand Mudsnail Positive Waters in Colorado
Year First Detected
|South Platte River (just below Eleven Mile dam in Park County)||2004|
|Boulder Creek, City of Boulder||2004|
|Green River within Dinosaur National Monument||2005|
|Dry Creek, City of Boulder|
(2 distinct populations)
|South Delaney Buttes State Wildlife Area (Jackson County)||2010|
|East Delaney Buttes State Wildlife Area (Jackson County)||2011|
|Eleven Mile Reservoir State Park & Charlie Meyer SWA||2011|
|College Lake, CSU, Fort Collins||2011|
|Spinney Mountain State Park||2012|
|Gunnison River (West of Delta)||2016|
|Fourmile Canyon Creek (Boulder County)||2017|
|South Platte River (Near Deckers)||2017|
|Uncompahgre River (Town of Montrose)||2017|
|Jimmy Camp Creek||2018|
|Chatfield Pond #1||2019|
|Elmer’s 2 Mile Park (Boulder County)||2019|
|South Platte River (City of Denver)||2020|
|South Boulder Creek||2020|
|Colorado River (Near Parachute)||2022|
|Highline Government Canal||2022|
|St. Vrain Creek||2022|
*Click on map for larger version
Help prevent the spread of New Zealand Mudsnails!
Keep all gear free of mud, plants, and organic debris in between each and every use. Unknowingly moving a species from one body of water to another, even within different stretches of the same river, can start a domino effect of invasion, causing irreversible ecological damage. It is especially important to keep waders clean.
People recreating in Colorado's waters should scrub the bottom of boots or waders with a brush and remove all mud, plants, and organic materials in
between each and every use. They should then perform ONE of the following options before going into the next body of water:
Submerge waders and gear in a large tub filled with a mixture of 6 ounces per gallon quaternary ammonia-based institutional cleaner (such as Super HDQ Neutral) and water for at least 10 minutes, scrubbing debris from the gear, and visually inspecting the gear for snails before rinsing. Follow all precautionary label instructions! Rinse water must be from a New Zealand mudsnail-free source (to avoid re-infection), and the chemical bath must
be properly disposed of, away from the water body.
Spray or soak waders and gear with 140º Fahrenheit water for at least 10 minutes.
Dry your waders and equipment completely for a minimum of 10 days in between each use (remember that mudsnails can survive several days out of water).
Place waders and boots in a freezer overnight between use.
Thank you for protecting Colorado’s waters from the harmful impacts of invasive species!