Keeping Invasive Mussels out of Colorado

As boating season approaches, we continue to ask for help from boat owners in maintaining our mussel-free status.
boat inspection
Colorado Parks and Wildlife’s aquatic nuisance species Inspector Travis Beam checks a boat for invasive mussels at the Loma Point of Entry on May 15, 2022.

More boats requiring decontamination due to fouling by destructive mussels entered Colorado in 2021 compared to previous years, but the statewide inspection program coordinated by Colorado Parks and Wildlife again succeeded in keeping invasive mussels out of the state’s lakes and reservoirs.

“Colorado Parks and Wildlife continues to meet the challenge of protecting the state’s waters and infrastructure from aquatic nuisance species,” said Robert Walters, Colorado Parks and Wildlife’s aquatic nuisance species program manager. “But as boating season approaches we continue to ask for help from boat owners in maintaining our mussel-free status.”

Mussels are destructive to aquatic habitat, can seriously damage reservoir infrastructure, and cause problems on boats.

A Busy Year for Anuisance Species Inspectors

boat inspection station
Boat Inspection Station

Colorado’s aquatic nuisance species inspectors were busy during 2021. Staff conducted a total of 514,028 inspections and decontaminated 27,877 boats suspected of carrying mussels, other aquatic invasive species or standing water. Most concerning is the continued increase in the number of boats fouled with mussels. In 2019, 86 boats were found to be fouled with invasive mussels. In 2020, that number jumped to 100. And in 2021 that skyrocketed to 181. Only 16 boats with mussels were found in 2017.

Contaminated boats come into Colorado from neighboring states, especially Utah and Arizona because of our proximity to Lake Powell which has been mussel-infested for years. Other neighboring states with mussel infestations include Kansas, Nebraska, Oklahoma, Texas and South Dakota. Most Midwestern and East Coast states also have infested waters.

A Coordinated Effort

In 2021, Colorado Legislature passed House Bill 21-1226 which authorized Colorado Parks and Wildlife to implement a pilot roadside watercraft inspection and decontamination program. In 2022, the Aquatic Nuisance Species Check Station at the Loma Port of Entry on I-70 will be checking vehicles with watercraft on May 15, July 23 and September 5

Some of the increase in inspections can be attributed to the large influx of outdoor recreation Colorado has experienced since the start of the pandemic. Colorado Parks and Wildlife understands that outdoor recreation is important to everyone’s physical and mental health and the state made a commitment to keep state parks open during the pandemic.

Since CPW’s ANS inspection program started in 2008, 6.1 million boats have been inspected and 172,460 boats have been decontaminated. The agency is aided in the program by Colorado counties, municipalities, water districts, federal agencies and private companies that also conduct inspections. CPW also works proactively looking for aquatic nuisance species by sampling waters throughout the state. In 2021, crews sampled 157 standing waters and eight flowing waters. The National Park Service provided CPW with 31 water samples.

Vigilant in the Fight Against Mussels

boat inspection
Inspectors are checking the

CPW has also been instrumental in establishing the Water Inspection and Decontamination (WID) protocols which are now used by states throughout the West. Agency staff also are active with the Western Regional Panel on Aquatic Nuisance Species Watercraft Inspection and Decontamination Committee.

Walters said that CPW will always remain vigilant in the fight against mussels.

“Mussels aren’t going away. However, by continuing our preventative watercraft inspection program we can keep Colorado’s waters free of invasive mussels.”

CLEAN, DRAIN, and DRY.  Every Time!

Boat owners are reminded to “clean, drain and dry” boats after every use. Boaters should also inspect their trailers and look in hard-to-reach spots on boats and engines for evidence of mussels. Anyone who has used a boat in waters outside of Colorado should tell boat inspectors. Boat owners can also call any state park or wildlife office if they have questions or concerns.

Follow these guidelines ​before leaving a body of water:


  • Remove any visible plant or plant fragments as well as mud or other debris. Plant material, mud and other debris routinely contain other organisms that may be an aquatic nuisance species, and plant fragments and animals can survive in mud many days out of water. Some plant species are aquatic nuisance species. 
  • Check trailer, including axel and wheel areas – in and around the boat itself: anchor, props and jet engines, ropes, boat bumpers, paddles.
  • Clean, ​​​check and dry off all parts and equipment that c​ame in contact with water.
  • Empty bait buckets into trash. Do not empty any bait fish into the lake or reservoir.


  • Drain every conceivable space or item that can hold water.
  • Follow factory guidelines for eliminating water from engines. All engines hold water, but jet drives on personal watercraft and other boats can hold extra water.
  • Remove the drain plug from boats and put boat on an incline so that the water drains out.​​​​
  • Drain live-wells, bilge, ballast tanks and transom wells.
  • Empty water out of kayaks, canoes, rafts, etc.


  • Allow everything to completely dry before launching into another body of water.

Information for Boaters

Boater’s Guide to Aquatic Nuisance Species (ANS) Inspections

Boaters should take full advantage of Colorado’s green seal and receipt program, which provides documentation of compliance and will reduce wait times to get through inspection station lines and get you on the water faster. All stations use green seals. However, waters that are positive for ANS use blue receipts, while waters that are negative use white receipts. For more details, visit the CPW WID Manual.

Check out the map of Statewide Watercraft Inspection and Decontamination Sites​​​​​​ in Colorado.

Please read the Boater’s Guide to Aquatic Nuisance Species (ANS) Inspections to educate yourself on the requirement to boat in Colorado and how you can protect our waters by helping to stop the spread of invasive species.

Don’t Move a Mussel! Getting Tough on Aquatic Nuisance Species

In the following video, CPW educator Jessie explores how Coloradans and Colorado Parks and Wildlife are protecting Colorado’s waters from aquatic nuisance species.

Video: Don’t Move a Mussel! Getting Tough on Aquatic Nuisance Species

Please visit the Colorado Parks and Wildlife Website, for more information about aquatic nuisance species and CPW’s program.

Travis Duncan is a public information officer for Colorado Parks and Wildlife in Denver. Travis has lived in Colorado nearly 20 years and loves the outdoors. If you have a question, please email him at

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