Colorado River Zebra Mussel Spread Continues as CPW Ramps Up 2026 Monitoring
Colorado Parks and Wildlife has launched its 2026 aquatic nuisance species sampling program along the Colorado River, expanding monitoring efforts in response to the ongoing zebra mussel infestation that has grown significantly since first detected in 2024.
CPW staff will conduct weekly shoreline and water sampling along sections of the Colorado River between Granby and the Colorado-Utah border. The intensified effort follows the discovery of zebra mussel larvae in the river in July 2024 and adult mussels confirmed in 2025.
This year, CPW is expanding its partnership with River Corps, an AmeriCorps program operated by the nonprofit River Science. Three River Corps members have been placed within CPW’s aquatic nuisance species program, two of whom are dedicated to increasing the agency’s Colorado River monitoring capacity. Technicians will collect water samples using plankton nets to survey for invasive mussels at different life stages. High-priority samples will be evaluated for zebra mussel environmental DNA at CPW’s Aquatic Animal Health Lab in Denver.
The list of infested water bodies in western Colorado continues to grow. Currently designated as infested include Highline Lake at Highline Lake State Park, Mack Mesa Lake at Highline Lake State Park, West and East Lake at James M. Robb-Colorado River State Park, the Colorado River from the Eagle River confluence to the Utah border, Red Rocks Lake at James M. Robb-Colorado River State Park, and Grand River Park in New Castle.
CPW has also identified several privately owned water bodies with confirmed infestations and anticipates additional discoveries as sampling expands.
No detections have been recorded between the Colorado River headwaters and the Eagle River confluence, or in the Eagle or Roaring Fork rivers.
CPW is urging anyone who owns a pond or lake drawing from the Colorado River or Grand Valley canal systems to request a free inspection by emailing Invasive.Species@state.co.us. Boaters and anglers are reminded to clean, drain, and dry all watercraft and gear after every outing.
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