Colorado is waging war against tiny, fast-reproducing invaders — the notorious zebra mussel — and state experts have one message for anyone getting outside this Fourth of July: Clean your gear.
The state’s first adult zebra mussel showed up in Highline Lake State Park near Grand Junction in 2022. Colorado officials have largely focused its efforts to limit the mussels’ spread on boats with motors moving among reservoirs, since they’re one of the easiest ways for invasive pests to hitchhike across large distances.
But now, with the invasive species popping up in the Colorado River, the state is expanding its warning to include any kind of gear: paddleboards, kayaks (inflatable or not), canoes, fishing gear, waders, boots, river shoes. The list goes on.
“In light of finding zebra mussel veligers and adults within the main stem of the Colorado River, that really heightened our awareness to the risk posed by nonmotorized water users,” said Madeline Baker, an invasive species specialist with Colorado’s Aquatic Nuisance Species program.
Zebra mussels start out life as microscopic organisms called veligers. These are invisible to the naked eye but can hide in small amounts of water. That includes the little pool of water left in your canoe or kayak, or the moisture left in duckies and paddleboards before they’re rolled up, Baker said.
These veligers can live in standing water for 30 days or more, she said.
“We just really want to make sure that people are completely draining and drying their craft as best as they can,” Baker said.
Adult zebra mussels, about the size of a thumbnail with a zebra-striped shell, reproduce quickly and can clog up pipes, valves and parts of dams that send water and hydropower to communities, costing millions of dollars to remove. They also suck up nutrients, outeating other native aquatic species, and their razor-sharp shells cause headaches for beachgoers.
The mussels have already spread across much of the eastern half of the country. States in the Great Lakes region in 2012 reported spending more than $100 million annually just to control invasive species, including zebra mussels, enough to maintain normal operation of their hydropower facilities and water plants, Baker said.
“We are fortunate that we are doing everything that we can to stay ahead of those impacts,” Baker said, “but the future is uncertain on how it will play out.”
Colorado has been working to keep these invasive species out of its waters since 2007, when a task force was created to coordinate management efforts.
In 2008, Colorado approved a law that makes it illegal to possess, import, export, transport, release or cause an aquatic nuisance species to be released.
Their appearance in Highline Lake in Mesa County meant they’d made it to Colorado. Last July, the mussels showed up in a private reservoir in Eagle County near the Colorado River. And in September, specialists found adult zebra mussels in a stretch of the Colorado River itself.
As of Tuesday, the list of infested bodies of water has grown to six:
- Highline Lake at Highline Lake State Park (2022)
- Mack Mesa Lake at Highline Lake State Park (2025)
- West and East Lake at the wildlife area section of James M. Robb-Colorado River State Park (2025)
- Colorado River from the confluence of the Eagle River downstream to the Colorado-Utah border (2025)
- Red Rocks Lake at the Fruita section of James M. Robb-Colorado River State Park (2025)
- Grand River Park in New Castle (2026)
The town of New Castle declined to comment on the state’s newest infestation at Grand River Park, referring questions to Colorado Parks and Wildlife. CPW also declined to share details of the infestation.
How to clean your gear
The state’s cleaning recommendations are geared to prevent the spread of zebra mussels and their co-invaders, like quagga mussels and New Zealand mudsnails, which reproduce through asexual cloning.
Think about hiking, Rachael Gonzales, a Colorado Parks and Wildlife spokesperson, said. As people cross streams and visit high alpine lakes, they could be picking up the tiny snails or veligers in the mud on their boots.
“Just clean your gear after every use,” Gonzales said. “Even if you are recreating in the same area, just take that extra step and make sure you are going in with clean gear.”
When it comes to cleaning gear, Baker urged people to focus on the big three: mud, plant material and moisture. That includes mud on boots and any standing water or wet areas of paddle boards before you roll them up.
“If you remove those three things, there’s a good chance that you are not going to be transporting any aquatic nuisance species,” Baker said.
The state has set up waterless cleaning stations around Colorado and along the now-infested Colorado River. These stations are intended to be waterless so contaminated water and plant life doesn’t wash back into rivers, streams and lakes. They come with air compressors, vacuums, tongs to remove plant materials, boot brushes and other tools.
Do you use waders or end up with muddy boots after hanging out near a river, stream or lake? Next time you go to the store, look for household products like white vinegar or disinfectants with quaternary ammonium (there are many brands) and add cleaning with the ammonium solution to your to-do list. For other species, like New Zealand mudsnails, Formula 409 disinfectant is a good option.
Not into that idea? Try cleaning with hot water (aim for 140 degrees Fahrenheit), sticking waders and boots into a freezer overnight, or letting gear dry in the sun for 10 days, Baker said.
“Sometimes people ask us questions about what stretches of the river are infested and what bodies of water might have aquatic nuisance species,” Baker said. “I would say you should just practice the habit, no matter where you’re recreating, every single time.”