CPW resumes ANS sampling efforts in the Colorado River for 2026

Colorado Parks and Wildlife invasive species specialist throws a plankton tow into the Colorado River to collect water samples for zebra mussel testing. CPW/R. Gonzales

May 13, 2026

 

GRAND JUNCTION, Colo. — Colorado Parks and Wildlife (CPW) has begun aquatic nuisance species (ANS) sampling efforts on the Colorado River for 2026. CPW staff will conduct weekly shoreline and water samplings along sections of the Colorado River between Granby and the Colorado-Utah border. These frequent samplings are part of CPW’s increased efforts following the discovery of zebra mussel veligers (larvae) in the river in July 2024 and adult zebra mussels in the river in 2025.

In 2026, CPW is expanding our partnership with River Corps, an AmeriCorps program operated by the nonprofit River Science, which places members with organizations and agencies throughout Colorado. River Science members help their assigned organizations improve the efficiency, efficacy and scale of river data and management to improve recreation, water resources, and overall resiliency. Three River Corps members have been placed with staff from CPW’s ANS program, two of whom are focused on expanding CPW’s capacity to monitor the Colorado River.

CPW and River Corps ANS technicians will utilize different techniques, including collecting water samples using a plankton net, to survey for invasive mussels. Each of these techniques will target a different life stage of the species. Water samples will be sent to the ANS lab in Denver to be evaluated for the presence of mussel veligers. High-priority samples will also be evaluated for the presence of zebra mussel eDNA at CPW’s Aquatic Animal Health Lab.

In addition to increased sampling, CPW ANS technicians, wildlife officers, and state park staff will continue increased education efforts through the summer months at boat launches between Palisade and Loma.

CPW staff will continue working closely with our partners at the U.S. Fish and Wildlife Service on sampling efforts in the Colorado River.

The following bodies of water have the designation of “infested” with zebra mussels:

• 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)

In addition to the above-mentioned bodies of water, CPW has identified several privately owned bodies of water infested with zebra mussels. CPW ANS staff anticipates additional discoveries with the increased sampling efforts on private bodies of water in the Grand Valley. 

No detections of zebra mussels have occurred between the headwaters of the Colorado River and the confluence of the Eagle River.

No detections of zebra mussels have occurred in the Eagle or Roaring Fork rivers.

Oh, Shell No!
The Colorado Parks and Wildlife Aquatic Nuisance Species team is asking for your help. If you own a pond or lake that utilizes water from the Colorado River or Grand Junction area canal systems, CPW would like to inspect your body of water. You can request sampling of your body of water by emailing CPW staff at [email protected].

“Despite these additional detections, it remains critical for the continued protection of Colorado’s aquatic resources and infrastructure to fully understand the distribution of zebra mussels in western Colorado,” said Robert Walters, CPW’s Invasive Species Program Manager. “We can only achieve this with the assistance and participation of the public.”

In addition to privately owned ponds and lakes, CPW  also encourages those who use water pulled from the Colorado River and find any evidence of mussels to send photos to the above email for identification. It is extremely important to accurately report the location in these reports for follow-up surveying.

Prevent the Spread: Be a Pain in the ANS
With the additional discoveries of adult zebra mussels, it is even more important for everyone to play their part in protecting Colorado’s bodies of water and preventing the spread of ANS. Simple actions like cleaning, draining and drying your motorized and hand-launched vessels — including paddleboards and kayaks — and angling gear after you leave the water can make a big difference to protect Colorado's waters.

Learn more about how you can prevent the spread of aquatic nuisance species and tips to properly clean, drain and dry your boating and fishing gear by visiting our website. Tips for anglers and a map of CPW’s new gear and watercraft cleaning stations are available here.

# # #

Media Kit: OH Shell NO! Media Kit: Photos and videos from 2022 - 2025