When state wildlife officials first found signs of invasive zebra mussels in a reservoir in western Colorado several years ago, they took steps to halt an infestation and try to prevent their spread into the Colorado River: partially drain the lake and deploy a pesticide that targets mollusks.
It failed.
Even after Colorado Parks and Wildlife intensified its efforts — more pesticide and a complete closure of the lake in summer 2024 — monitoring still turned up mussel veligers, or the larval stage of the species visible only under a microscope.
As it turns out, Colorado wildlife officials were battling an even bigger issue: a privately owned body of water in Eagle County that had become home to a well-established population of adult zebra mussels and is believed to be the source of the infestation.
