Click the link to read the article on the Colorado Parks & Wildlife website (Rachael Gonzales):
November 13, 2025
GRAND JUNCTION, Colo. — On Oct. 29, over 70 people from multiple partner agencies and groups joined Colorado Parks and Wildlife (CPW) for a one-day sampling effort on the Colorado River. From the headwaters in Grand County to Westwater, Utah, volunteers from nine agencies spent the day floating the river in search of adult zebra mussels.
Similar surveys were conducted on the Eagle and Roaring Fork rivers, as well as the tail end of the Gunnison River near the confluence of the Colorado River.
The rivers were divided into smaller sections to simplify the identification of potential zebra mussel habitat and maximize the amount of surveying that could be done in each section. Stopping at points along the way, teams conducted shoreline surveys by inspecting rocks and other hard surfaces where zebra mussels may attach.
Staff and volunteers sampled approximately 200 locations, covering over 200 miles between the four rivers.
Through this sampling effort, CPW confirmed a single adult zebra mussel in the Colorado River near Rifle. During surveys following the large-scale effort, CPW Aquatic Nuisance Species (ANS) staff discovered additional adult zebra mussels within Glenwood Canyon.
With these new findings, the Colorado River is now considered infested from the confluence of the Eagle River down to the Colorado-Utah border.
“Although it is disappointing to have found additional zebra mussels in the Colorado River,” said Robert Walters, CPW’s Invasive Species Program Manager, “this survey achieved its primary objective of gaining a more comprehensive understanding of the extent of the zebra mussel population in western Colorado.”
To date, no zebra mussels — adult or veliger — have been found in the Colorado River upstream of the confluence with the Eagle River.
As a result of the one-day sampling effort, CPW also confirmed the presence of New Zealand mudsnails in the Roaring Fork River. While New Zealand mudsnails have previously been identified in the Colorado, Gunnison and Eagle rivers, this is the first time they have been detected in the Roaring Fork River.
“We could not have pulled off such a massive effort without our partners. These partnerships are instrumental in the continued protection of Colorado’s aquatic resources and infrastructure from invasive mussels,” said Walters.
CPW would like to thank the following agencies and groups who also participated in the one-day sampling effort, in addition to our federal partners at the U.S. Fish and Wildlife Service and Bureau of Reclamation:
- City of Grand Junction
- Eagle County
- Mesa County
- Orchard Mesa Irrigation District
- Roaring Fork Conservancy
- Utah Department of Natural Resources
“It’s not just our federal, state and local partners that play a role in understanding the extent of zebra mussels in the Valley, but also the general public,” Walters continued. “That is why we are continuing to ask for the public’s help.”
If you own a pond or lake that utilizes water from the Colorado River or Grand Junction area canal systems, CPW would like to sample your body of water. You can request sampling of your body of water by CPW staff at Invasive.Species@state.co.us.
In addition to privately owned ponds and lakes, CPW also encourages those who use water pulled from the Colorado River and find any evidence of mussels or clams to send photos to the above email for identification. It is extremely important to accurately report the location in these reports for follow-up surveying.
CPW will continue sampling through Thanksgiving, focusing on smaller ponds in the Grand Valley.
Prevent the spread: Be a Pain in the ANS
Simple actions like cleaning, draining and drying your motorized and hand-launched vessels — including paddleboards and kayaks — and angling gear after you leave the water can make a big difference to protect Colorado’s waters.Learn more about how you can prevent the spread of aquatic nuisance species and tips to properly clean, drain and dry your boating and fishing gear by visiting our website. Tips for anglers and a map of CPW’s new gear and watercraft cleaning stations are available here.
