News Article

Clean! Drain! And Dry! Your boats, waders, tires, paddleboards and fishing gear

What you can do to help protect Colorado’s headwaters from invasive aquatic species.

Colorado officials are calling on people who boat, fish, wade, paddleboard or simply float on the state’s streams, rivers and reservoirs to do their part to help stop the spread of invasive aquatic species into mountain waterways.

The majority of aquatic nuisance species spread by hitching rides on boats, motors, trailers and other watercraft. Cleaning, draining and drying boats, waders, tires, paddleboards, kayaks and fishing gear can help prevent their spread.

A boat propeller is covered in zebra mussels. — Zebra mussels encrusted on a boat propeller. Photo credit: National Park Service via Wikimedia Commons.

Preventing the spread of two specific species, the zebra mussels and their cousins the quagga mussels, took on heightened importance this summer.

In July 2025, the Colorado Parks and Wildlife department announced that the Colorado River is now considered “positive” for zebra mussels from where the river meets the Roaring Fork River at Glenwood Springs downstream to the Colorado-Utah border.

The department, which has been on the lookout for the aquatic nuisance species since 2008, said in July that testing had confirmed the presence of adult zebra mussels, which can clog pipes and infrastructure and damage aquatic ecosystems, in a private lake in western Eagle County.

Additional zebra mussel veligers, the mussel’s larval stage, were confirmed in the Colorado River at New Castle, downstream of Glenwood Springs, and in the Highline and Mack Mesa lakes at the Highline Lake State Park near the Colorado-Utah border.

A close-up of a zebra mussel. — Two invasive zebra mussels, seen with striped shells, cling to the shell of a North American native freshwater fatmucket mussel. Photo credit: US Fish and Wildlife Service, Mara Koenig.

CPW Director Jeff Davis credited the new discoveries of adult zebra mussels and veligers in Colorado’s waterways to the dedicated work of the department’s aquatic nuisance species staff to collect and test water samples throughout the state.

“This discovery is a significant step toward identifying a potential source of zebra mussels and advancing our efforts for eradication,” Davis said in the July 2025 announcement.

It’s also a chance for everyone who recreates on Colorado’s rivers, streams and reservoirs to redouble their efforts to help prevent the zebra mussels’ spread, as the mussels typically spread by hitching rides on boats, paddleboards, kayaks and fishing gear.

“These new test results give us a heightened sense of concern, as Colorado is a headwaters state and it’s up to all of us to protect our waterways,” said Brandon Ransom, Denver Water’s manager of recreation.

“People need to stay vigilant and do their part to keep these invasive species out of our waterways,” he said.

A woman cleans a paddleboard. — Colorado Parks and Wildlife is installing cleaning stations for paddleboards, kayaks, fishing gear and motorized boats around the state to help recreators prevent the spread of aquatic nuisance species in the state’s waters. Photo credit: Colorado Parks and Wildlife.

Adult mussels can attach to any surface and can live several days out of water (depending on the time of year) in moist, shaded areas. The microscopic mussel larvae (known as veligers) can be transferred in water contained in live wells, bilge, ballast tanks or “minnow” buckets.

“It just takes a few microscopic larvae entering the reservoir, or adults attached to a boat, and before you know it these mussels can overtake dams, valves and pipes, causing millions of dollars of damage to critical drinking water infrastructure,” Ransom said.

Denver Water, which gets half its water supply from the Colorado River, allows motorized boating on its Antero, Dillon, Eleven Mile and Williams Fork reservoirs. Nonmotorized boating is allowed on Gross Reservoir in Boulder County.

What is Denver Water doing to help prevent the spread of these aquatic nuisance species?

Denver Water reservoirs are regularly sampled and tested as part of CPW’s aquatic nuisance species monitoring program, Ransom said.

A person washes off boots. — Cleaning, draining and drying fishing gear, along with nonmotorized and motorized boats, helps prevent the spread of aquatic nuisance species. Cleaning stations are available around the state. Photo credit: Colorado Parks and Wildlife.

And since 2008, Denver Water has paid $200,000 a year for CPW to conduct boat inspections at Antero, Eleven Mile and Williams Fork reservoirs. The utility also pays for inspectors, at a cost of $95,000 in 2025, to be stationed at Frisco and Dillon marinas on Dillon Reservoir in Summit County.

Motorized boats must be inspected before they’re allowed onto the reservoirs.

And those inspectors have proved crucial, Ransom said.

During the first week of the 2025 boating season, two boats were flagged and barred from entering Dillon Reservoir due to evidence of mussels on the boat. Samples from the two boats (one boat at the Dillon Marina and a second boat at the Frisco Marina) tested positive for zebra mussels, Ransom said.

The utility also has Colorado Parks and Wildlife’s watercraft or gear cleaning stations (find a map of cleaning stations statewide) available for recreators to take advantage of at:

Antero Reservoir — One cleaning station is on the north ramp and another one is on the south ramp.
Gross Reservoir — A station for cleaning nonmotorized boats is now available.
Eleven Mile Reservoir — A new station is planned for 2025.
Waterton Canyon — A new wader cleaning station is planned in Waterton Canyon in 2025.
The South Platte River near Deckers, between the Cheesman and Strontia reservoirs — New wader cleaning stations are planned in 2025.

“We want people to have a fun day on the water,” Ransom said. “We just ask that visitors remain mindful of how critical these waterways are to Denver Water’s drinking water system and continue to be responsible stewards of these facilities.”