The Highline Government Canal and Colorado River were declared positive for zebra mussels after additional sampling detected mussel veligers.

One additional zebra mussel veliger was discovered and confirmed in the Government Highline Canal. Two additional veligers were discovered and confirmed in the Colorado River at two separate locations between De Beque and Grand Junction. There have been no veligers found upstream of the Beavertail Mountain Tunnel in De Beque Canyon nor have any adult mussels been found in the canal or river. A veliger is the free-floating larval stage of the mussel.

“These results will help guide us on the next steps as we continue working closely with our partners to work on a plan to protect our natural resources and infrastructure crucial to the Grand Valley, including our goal of locating the source,” said Jeff Davis director of Colorado Parks and Wildlife (CPW).

Zebra mussels pose ecological effects, hurting native fish populations due to their filter-feeding strategies that strip essential prey items, such as plankton, from the water. Zebra mussels also pose a risk to infrastructure that pulls water from the Colorado River. Female zebra mussels can produce up to 1 million eggs in a spawning season. As they mature, mussels bond to surfaces with byssal threads, making them difficult to remove. This rapid reproduction coupled with their attachment by byssal threads can lead to clogged water infrastructures and long-term
maintenance issues.

CPW Aquatic Nuisance Species (ANS) and Northwest Region aquatics staff, along with the U.S. Fish and Wildlife Upper Colorado Native Fish Recovery Program and U.S. Bureau of Reclamation will continue sampling in the Colorado River and Grand Valley canal systems to attempt to locate the source of the zebra mussel veligers.

In addition to sampling, CPW will continues increased education efforts on the Colorado River, including voluntary watercraft inspections. CPW encourages anyone boating, floating, paddling or fishing in the Colorado River to clean, drain and dry their vessels and equipment, including motorized boats, rafts, paddle boards, kayaks and fishing gear after exiting the river.

CPW is evaluating options for the management of Highline Lake. The state agency drained Highline Lake west of Grand Junction as part of additional efforts to eradicate an infestation of zebra mussels there.