As enjoyers of our aquatic playgrounds in the summertime, most of us that fish and boat are aware that human activity has impacts. We’re probably less conscious that our own recreation practices may be leaving a mark. Invasive pests known as aquatic nuisance species are a growing threat to our water systems. These aquatic hitchhikers include disease-spreading bacteria, animals, and plants — some can be seen, others can’t. As non-native species they have no natural competition or predator, which makes it easy for them to spread rapidly and decimate our native species.


Some of the worst offenders in Colorado include zebra and quagga mussels, the New Zealand mudsnail and Eurasian watermilfoil.

Their impacts are big enough for the state of Colorado to have a budget of over $5 million for the control of aquatic nuisance species.

Zebra and quagga mussels can wreak havoc on boat engines and water supply infrastructure by encrusting and clogging pipes and fans. The New Zealand mudsnail feasts on the same aquatic insects that form the foundation of our native species’ food supply, surviving up to 50 days on a damp surface and several days on a dry one. Eurasian watermilfoil forms dense mats of noxious weeds that choke out native plants, slow water flow, invite mosquitoes to breed and decrease the water’s oxygen content. All of this inhibits swimming, fishing and boating.


In Eagle County, didymo (“rock snot”), the rusty crayfish and whirling disease are rampant in our waterways. Didymo or “rock snot” produces thick brown or bright green algae blooms that line stream bottoms and rocks, limiting oxygen for bottom-feeder organisms. The rusty crayfish is an intrusive and aggressive crustacean that feasts on the small insects and plant life that feed native fish.


Whirling disease causes skeletal and neurological problems and sometimes death, in young rainbow, brook and cutthroat trout. This is a particular issue at the confluence of the Eagle River and Lake Creek, where the substrate hosts the disease-causing tubifex worm. Colorado Department of Wildlife now stocks whirling disease-resistant rainbow trout to lessen the blow for the angling community, but mitigation efforts are costly and fail to completely solve the spread of disease, which makes prevention more important than ever.


Since 2008 the Aquatic Nuisance Species Act has required mandatory inspection for all out-of-state boats entering Colorado waters and all of the boats entering or leaving known aquatic nuisance species-positive and high-risk waters. While there are no Colorado Department of Wildlife inspection stations in our county, there are several in reservoirs frequented by Eagle County residents including Rifle Gap, Ruedi, Harvey Gap and Blue Mesa Reservoirs.


While Colorado has been a leader in aggressive aquatic nuisance species containment compared to its neighboring states, the program budget is facing major cuts. Only two local government contracts from Denver Water and Colorado Springs Utilities, in addition to contributions from the U.S. Forest Service, remain. If Colorado slashes its aquatic nuisance species programs, then an epidemic like that seen in other states will likely follow. In 2015, Colorado Department of Wildlife caught and decontaminated a record breaking number of out-of-state boats before they entered Colorado waters. Already in 2016 that record has almost been broken, providing clear evidence that this is not the time to cut the program.


You don’t need a boat to contribute to the spread, either. Even the most innocent behaviors can transfer these nuisance species to healthy streams. They can be spread by wading boots, fishing and construction equipment, bait, and standing water. Even our beloved pets can transport these pests from stream to stream so it’s important to check, brush and wash your dog’s coat and paws after every dip.


What’s the good news? Despite all of these issues, some relatively simple measures can make a huge difference and help stop the further spread of aquatic nuisance species in the waters we enjoy. Here are four ways to decontaminate anything that comes in contact with a water source.

Pick one:

• Dry equipment for a minimum of 10 days.

• Freeze equipment overnight.

• Clean with hot water (140 degrees) for a minimum of 10 minutes.

• Remove any mud, algae or debris and soak equipment for 10 minutes in a decontamination solution of 6 ounces of ammonia-based, industrial-strength cleaner per gallon of water.

Though these species have made it to the heavily traveled lakes and rivers in our county, many high mountain lakes and streams are as pristine as they were thousands of years ago. While I encourage everyone to seek out, explore, fish and enjoy their favorite mountain stream this summer, I urge you to consider what you may be bringing with you.


Nick Rzyska-Filipek is the habitat and restoration intern for Eagle River Watershed Council. The Watershed Council has a mission to advocate for the health and conservation of the Upper Colorado and Eagle River basins through research, education, and projects. Contact the Watershed Council at 970-827-5406 or visit

This article ran in the Vail Daily on July 18, 2016.