Zebra Mussels Found on Highline Lake Equipment

Colorado Parks and Wildlife staff identified a record number of invasive mussels during seasonal maintenance.

Updated on Oct. 30, 2026 in Hiking

Gouache-painted editorial illustration of mussel-covered wooden pilings in clear reservoir water, representing the ongoing environmental challenge of invasive species. — Colorado Parks and Wildlife officials confirmed a record-breaking number of zebra mussels on submerged equipment at Highline Lake this October. AI Illustration. Upload story photo >

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Colorado Parks and Wildlife officials discovered a record-breaking number of adult zebra mussels on docks and buoys at Highline Lake in October 2026. This finding follows years of ongoing efforts to control the invasive species within the state.

Why it matters

The discovery underscores the persistent challenge of managing invasive zebra mussels, which were first identified in the reservoir in 2022. Despite a full lake drainage in 2024, the presence of these shellfish continues to impact regional water bodies.

Staff identified the infestation after removing lake equipment on October 3, 2026. Previous eradication attempts included a 27-foot water level reduction in January 2023 and a full lake drainage in 2024.

The players

Colorado Parks and Wildlife

This state agency is responsible for managing Colorado's state parks and wildlife resources, including the monitoring and prevention of aquatic invasive species.

The details

Personnel inspected docks, buoys, and work boats during seasonal winter maintenance to track the scope of the infestation. Officials confirmed that the source of the broader infestation was traced to Eagle County in July 2025.

Zebra mussels were first discovered in Highline Lake in 2022.
The lake water level was lowered for eradication efforts in January 2023.
Colorado Parks and Wildlife drained the entire lake in 2024.
Zebra mussel veligers were identified in the Colorado River and Highline Canal during summer 2024.
Maintenance staff removed equipment for inspection on October 3, 2026.

Culture Shift

The discovery of adult mussels at Highline Lake indicates that the invasive species remains a persistent threat despite the 2024 full drainage of Highline Lake. This outcome marks a departure from hopes that total drainage would successfully eradicate the population.

Highline Lake State Park visitors should remain aware of strict equipment cleaning requirements to prevent the spread of invasive species to other waters. Colorado Parks and Wildlife does not currently plan to repeat the full lake drainage, meaning ongoing monitoring will continue.

The takeaway

Zebra mussels pose a continuous challenge for water management that requires constant vigilance from all lake users. Boaters and outdoor enthusiasts can help mitigate the spread by thoroughly cleaning and drying all equipment after every outing.