Help Wanted: Otero College: Coordinator of Payroll and Human Resources
Doc Jones and Co. Chuckwagon Supper and Music Show Sept 20 in La Junta, CO
Fine Arts League to Host Early Settlers Day Art Show Sept. 4-7
La Junta High School Pool Schedule
Bent's Old Fort NHS to Reopen for Guided Tours
SecoNews SwapShop

Oh Shell No! Colorado Parks and Wildlife Reports Zebra Mussels Invading Western Slope Waters


Description: The Colorado Parks and Wildlife Released the Following Information Regarding the Current Status of Colorado Waters Contaminated with Invasive Zebra Mussels on September 15, 2025...

Oh Shell No! Colorado Parks and Wildlife Reports Zebra Mussels Invading Western Slope Waters

GRAND JUNCTION, Colo. — Through ongoing increased sampling efforts on the Colorado River and nearby bodies of water, Colorado Parks and Wildlife (CPW) Aquatic Nuisance Species (ANS) staff have detected adult zebra mussels in the Colorado River and a nearby lake in Grand Junction.

“While this is news we never wanted to hear, we knew this was a possibility since we began finding veligers in the river,” said CPW Director Jeff Davis. “I can’t reiterate this enough. It was because we have a group of individuals dedicated to protecting Colorado’s water resources that these detections were made. It is because of these same dedicated individuals and our partners that we will continue our efforts to understand the extent of zebra mussels in western Colorado. ”

On Thursday, Aug. 28, the Aquatic Animal Health Lab (AAHL) notified Robert Walters, CPW Invasive Species Program Manager, that suspect veligers (the microscopic larval stage of zebra mussels) collected from West and East Lake, west of 31 Road within the Wildlife Area section of James M. Robb-Colorado River State Park, had tested positive for zebra mussel DNA. During a follow-up survey on Tuesday, Sept. 2, staff discovered suspected adult zebra mussels in the lake. 

Surveys were also conducted in the side channel, where water from the lake is released before flowing into the Colorado River.  During these subsequent surveys, additional suspect adult zebra mussels were found in the side channel and in the Colorado River where the side channel meets the mainstem of the river. 

Visual identification of the samples from the lake, channel, and river was performed by ANS staff. Samples were then sent to the AAHL for DNA confirmation. On Monday, Sept. 8, the AAHL confirmed the samples collected are adult zebra mussels. 

With this discovery, the Colorado River is now considered an “infested” body of water from the 32 Road bridge downstream to the Colorado-Utah border. This is the first time adult zebra mussels have been detected in the Colorado River. 

A body of water is considered “infested” when a water body has an established (recruiting or reproducing) population of invasive species; in this instance, multiple zebra mussel life stages have been found in that body of water. 

The following bodies of water have the designation of an “infested” body of water

  • Highline Lake at Highline Lake State Park (2022)

  • Mack Mesa Lake at Highline Lake State Park (2025)

  • West and East Lake at the Wildlife Area Section of James M. Robb - Colorado River State Park (2025)

  • Colorado River from 32 Road bridge downstream to the Colorado-Utah border (2025)

  • Private body of water in Eagle County (2025)

The Colorado River remains “positive” for zebra mussels from the confluence of the Roaring Fork River to the 32 Road bridge.

No detections of zebra mussels have occurred between the headwaters of the Colorado River and the confluence of the Roaring Fork River.

CPW, in collaboration with our partners at the local, state and federal levels, will continue our increased sampling and monitoring efforts from the headwaters of the Colorado River in Grand County to the Colorado-Utah border.  

“We won’t give up,” said CPW Invasive Species Program Manager Robert Walters. “Our priority remains utilizing containment, population management and education to protect the uninfested waters of the state.”

CPW will continue to evaluate options for the future containment and mitigation of Highline Lake, Mack Mesa Lake, and West and East Lake. CPW does not intend to treat the mainstem of the Colorado River due to multiple factors, including risk to native fish populations and critical habitat, length of the potential treatment area, and complexity of canals and ditches that are fed by the Colorado River.

Since sampling efforts began in mid-April, CPW has collected 427 water samples from various locations in the Colorado River. Of those samples, CPW has confirmed six samples to contain zebra mussel veligers. ANS staff has also collected 41 samples from the Eagle River and 42 samples from the Roaring Fork River. There have been no detections of zebra mussel veligers in the samples from the Eagle and Roaring Fork rivers. 

Private Body of Water in Eagle County treatment
During the week of August 25, CPW ANS staff treated a privately owned body of water in western Eagle County using EarthTec QZ, an EPA-registered copper-based molluscicide. In follow-up surveys conducted during the weeks of Sept. 1 and Sept. 8, staff observed positive initial results, having found dead adult zebra mussels in multiple areas around the body of water. CPW staff will continue to routinely monitor the water to evaluate its effectiveness. 

Oh, Shell No!
The Colorado Parks and Wildlife Aquatic Nuisance Species team is asking for your 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 inspect your body of water. You can request sampling of your body of water by CPW staff at Invasive.Species@state.co.us.

“Despite these additional detections, it remains critical for the continued protection of Colorado’s aquatic resources and infrastructure to fully understand the distribution of zebra mussels in western Colorado,” said Walters. “We can only achieve this with the assistance and participation of the public.”

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.

Prevent the spread: Be a Pain in the ANS
With the additional discoveries of adult zebra mussels, it is even more important for everyone to play their part in protecting Colorado’s bodies of water and preventing the spread of invasive species. 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.