Aquatic Nuisance Species

Aquatic Nuisance Species (ANS) are invasive plants and animals that hitchhike between waterways on boats, waders, boots, and gear - and they are here in the Roaring Fork Valley. Every water user has a role to play in stopping the spread. Learn what ANS are, what to look for, and how to slow the spread.

Be a Pain in the ANS: Say “trip’s over” to ANS

Many ANS can spread between bodies of water in ways we’re unlikely to notice. Once zebra mussels and other aquatic nuisance species establish themselves in a waterway, they are nearly impossible to remove. That’s why Colorado Parks & Wildlife (CPW) is working with anglers, boaters, and waterway recreationists to stop the spread before it’s too late. 

Clean, Drain, Dry - Every Time

Whether you are wading a stretch of river, floating a raft, or paddling a SUP, the ask is the same: Clean, Drain, and Dry all gear after every use, and before moving between waterways.

  • Clean off all mud, plant material, and organisms from your gear, hull, wader soles, fins, and compartments.
  • Drain every compartment, live well, bilge, and container that holds water.
  • Dry everything completely. Do not let water drain into gutters, storm drains, or near any waterway.
Person in yellow hat scrubbing a raft with a large cleaning brush

Find a Cleaning Station

Gear cleaning stations are available locally at Two Rivers Park in Glenwood Springs, the Carbondale Boat Launch, and at outfitter locations in Basalt. More stations will open this summer.

Button with text: Find a Cleaning Station

By taking these small but essential steps, you’re not just protecting your gear, you’re safeguarding Colorado’s rivers, lakes, reservoirs, and the future of fishing in our state.

zebra mussels attached to a log

What are Aquatic Nuisance Species?

Aquatic nuisance species (ANS) are invasive plants and animals that harm lakes, rivers, and streams by displacing native species and disrupting ecosystems. They also damage the infrastructure that delivers our drinking water and supports local agriculture.

Zebra mussel veligers were confirmed in the Colorado River in 2024, and New Zealand mudsnails were detected in the Roaring Fork River in 2025. The invasive species that water managers across the West have been working to keep out are now in our waterways. Once established, they are nearly impossible to eradicate.

Zebra, quagga, and golden mussels start as microscopic larvae called veligers that can survive in standing water inside a boat, wader, or water bottle. Adult mussels attach to hard surfaces in massive numbers, clogging irrigation pipes, water treatment systems, and reservoir infrastructure, reducing water flow and changing the taste and smell of drinking water.

New Zealand mudsnails are sometimes no larger than a grain of sand. They reproduce asexually, meaning a single snail can start an entirely new colony. They outcompete native aquatic insects that fish like trout depend on for food. When eaten by fish, they pass through the digestive system unharmed, leaving the fish malnourished and the snail free to keep spreading.

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