CPW provides update on zebra mussels in the Grand Valley

Rachael Gonzales
Northwest Region Public Information Officer
970-773-8587 / [email protected]
Twitter: @CPW_NW CPW provides update on zebra mussel veligers in the Colorado River and Government Highline Canal, and Highline Lake eradication plan

GRAND JUNCTION, Colo. — Colorado Parks and Wildlife concluded sampling efforts in the Colorado River and Government Highline Canal for 2024. As of Nov. 1, CPW staff collected nearly 450 water samples from the Colorado River, Government Highline Canal, James M. Robb-Colorado River and Highline Lake State Parks, as well as additional areas throughout the Grand Valley. In addition to samples collected by CPW, the Bureau of Reclamation (BOR), and the Grand Valley Water Entities collected additional samples within the canal system. No additional veligers or adult zebra mussels have been found in the Colorado River or Government Highline Canal since veligers were first found through routine testing in early July. 

In addition to sampling, CPW continued the increased education efforts on the Colorado River, including voluntary watercraft inspections. Since July, CPW worked with our local government and BLM partners to post signage and conduct education outreach at multiple water access points from the De Beque Canyon to the Utah Westwater boat ramp. Since July, CPW staff made more than 4,000 face-to-face educational contacts on the Colorado River. During one multi-day operation in July, staff talked to close to 600 people regarding the importance of cleaning, draining and drying their watercraft and equipment.

In early September, CPW ANS staff partnered with the United States Geological Survey (USGS) to install an autonomous sampler on the Colorado River near the Grand Valley Water Users Canal diversion. The sampler was programmed to collect eDNA samples from the river once per day and store them for up to eight days. Technicians collect the filters that the samples were collected on and replace them with new filters once a week.

“While we have concluded our sampling efforts for the year, our work is not done,” said Robert Walters, Invasive Species Program Manager. “Staff will continue to look for opportunities to educate the public on simple steps to prevent the spread of zebra mussels or any invasive species in Colorado waters.” 

Invasive species sampling will resume in the spring of 2025 once water temperatures are suitable for veliger production. With the designation of “positive” bodies of water, the increased sampling in the Colorado River and Government Highline Canal will continue for the next five years. 

On Monday, Nov. 18, Colorado Parks and Wildlife completed draining Highline Lake at Highline Lake State Park as part of the plan to eradicate zebra mussels from the lake. Small areas of water are expected to remain but are expected to evaporate with sun exposure or freeze with the colder temperatures. The lake will stay empty throughout the winter to expose as many areas as possible on the lake bed and shoreline, eliminating any remaining veligers or adult zebra mussels. During routine inspections in early November, park staff discovered five adult mussels, all of which were dead.

Highline Lake State Park staff does anticipate Highline Lake refilling and being open to boating in the spring of 2025. In anticipation of the upcoming boating season and in order to take advantage of low lake levels, the original boat ramp located on the west side of the park received much-needed repairs, including a new concrete pad. 

Recreational boaters and anglers can expect to see similar boating protocols in place for the upcoming 2025 boating season that were in place at Highline Lake State Park in 2023. These changes were put in place after the discovery of zebra mussels in September of 2022, prompting CPW to designate Highline Lake as Colorado’s first infested body of water.

What to expect for the 2025 boating season: 

• Boats launching​ at Highline Lake will continue to be subject to inspection and decontamination protocols before launching. 

• All boats must be clean, drained and dry prior to launching at Highline Lake or they will be decontaminated.

• Upon exiting the lake, all boaters will have their boats inspected and decontaminated, and they will be issued a green seal and a blue receipt​ that indicates it was last used on a body of water with a known aquatic nuisance species. The zebra mussel infestation is being fought at the source, and boats will not be permitted to leave the lake until they have been decontaminated by our team. 

​CPW will begin restocking Highline Lake following the return of normal water levels. Initially, catchable trout will be harvestable for anglers. Our longer-term plan is to develop a robust and diverse warm-water fishery that offers a variety of fish targeted by anglers and encourages ecological balance to enhance fish growth for memorable fishing and quality harvest. 

After the discovery of zebra mussels in the Government Highline Canal and Colorado River, CPW initiated the Invasive Species Rapid Response Plan and increased sampling efforts in the Colorado River from Glenwood Springs down to the Colorado-Utah border and within the Government Highline Canal. CPW staff will continue working closely with our partners at the Bureau of Reclamation, U.S. Fish and Wildlife Service, and Grand Valley Water Users Association on sampling efforts as we continue to learn more about the extent of zebra mussels in these locations and educate the public on prevention.

Questions from the media for the Bureau of Reclamation can be directed to BOR Public Affairs Specialist Justyn Liff at 970-248-0625 or [email protected].

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