State agencies report zebra mussel detections in Colorado River and stepped-up monitoring and treatments

Colorado Parks and Wildlife and Colorado Department of Agriculture officials described new detections of invasive zebra mussels and a scaling-up of sampling, lab capacity and coordinated containment efforts across western Colorado.

"At this time, we consider the Colorado River from Glenwood Springs to the state line all the way to Utah as positive for zebra mussels," Morgan Hoffman, an early-detection and sampling specialist, said, describing eDNA and veliger detections in 2024–2025 and the subsequent multi-entity response in the Grand Valley.

Hoffman reviewed the chronology: an adult zebra mussel was first detected at Highline Lake in 2022; follow-up eradication attempts (drawdowns and copper treatments) continued but subsequent sampling found veligers and eDNA signatures in Highline Canal and portions of the Colorado River in 2024–2025. A private Eagle County lake with heavy veliger counts and adults prompted a rapid treatment in which culverts were removed, and targeted application of EarthTec/ErBatek QC and further monthly monitoring was begun; managers said initial results from the treatment were promising but that five years of monitoring are required by regulation to delist a waterbody.

Officials described expanded lab capacity (multiplying technician staff and increasing equipment), weekly sampling on the Colorado River with roughly one-week turnaround for samples, use of eDNA and substrate monitoring, and coordination with irrigation districts and universities on response planning. They emphasized that quick detection, multiagency planning and regular monitoring are central to containment and response.