CPW announces additional zebra mussels found at Highline Lake State Park

Rachael Gonzales
Northwest Region Public Information Officer
970-773-8587 / [email protected]
Twitter: @CPW_NW CPW announces additional zebra mussels found at Highline Lake State Park

Five adult zebra mussels were found on the bottom of buoys located throughout Highline Lake on Sunday, Oct. 1.  Photo credit: CPW/R. Gonzales

GRAND JUNCTION, Colo. - One year after discovering zebra mussels at Highline Lake State Park, Colorado Parks and Wildlife staff found additional zebra mussels on Sunday, Oct. 1 during routine work to remove buoys from the water in preparation for winter. Five adult zebra mussels were found on the bottom of buoys located throughout the lake.

“This is heartbreaking,” said Robert Walters, Invasive Species Program Manager. “We knew this was a possibility, but held out hope lowering lake levels to expose shoreline and the application of EarthTech QZ would effectively eradicate the zebra mussels that were discovered last fall.”

Additional work is scheduled for October 12 to remove boat docks and two CPW boats. Once removed from the lake, boats and boat docks will be inspected for zebra mussels and decontaminated. 

Colorado Parks and Wildlife staff is currently evaluating multiple options in our efforts to both eradicate zebra mussels from Highline Lake and continue protecting other bodies of water in Colorado. While a new plan has not been finalized, all options being considered will have significant impacts on the fishery, boating and other water-based recreational opportunities in Highline Lake. This may include lowering or draining Highline Lake in 2024. 

Effective Monday, Oct. 9, an emergency fish salvage is in place at Highline Lake until further notice. All bag and possession limits for the reservoir are removed for the duration of the salvage. Anglers can keep all of the fish they catch utilizing the lawful angling methods currently allowed at the lake, but are reminded that all fish caught must be dead prior to leaving the lake. 

This fish salvage is only in effect at Highline Lake and DOES NOT include Mack Mesa Lake where all regulations remain in effect. 

“Eradicating invasive mussels is extremely difficult, which is why we focus so heavily on preventing their introduction," said Walters. “While this is disappointing, we are not considering this first attempt a failure. We believe if we had done nothing we would be looking at a much larger infestation today with fewer options for eradication and a greater chance of zebra mussels spreading to other bodies of water in Colorado.”

Anglers and waterfowl hunters are reminded to clean, drain, and dry their gear before going to and entering any new body of water. 

Media advisory
Colorado Parks and Wildlife is inviting the media to Highline Lake State Park on Thursday, Oct. 12. Media in attendance will have the opportunity to get video of CPW staff removing and inspecting boat docks and boats from the lake, as well as interview Colorado Parks and Wildlife staff.

Details
What: Highline Lake boat and dock removal
When: Thursday, Oct. 12 beginning at 10 a.m.
Where: Highline Lake State Park west boat ramp
Interview opportunities:

• Invasive Species Program Manager Robert Walters
• Highline Lake State Park Manager Alan Martinez
• Senior Aquatic Biologist Ben Felt

Media wishing to participate must RSVP to NW Region Public Information Officer Rachael Gonzales at [email protected] by close of business on Wednesday, Oct. 11. 

Background: Discovery of zebra mussels in Highline Lake at Highline Lake State Park
On Sept. 14, 2022, a single adult zebra mussel was discovered on an artificial PVC substrate in the lake during routine invasive species sampling. Additional zebra mussels would be discovered on docks and boats following increased sampling after the first mussel was found. This discovery of additional invasive mussels in the water prompted CPW to change the status of the body of water from “Suspect” to “Infested.” This is the first time a body of water has been categorized as infested with zebra mussels in the state of Colorado.

In November 2022, Highline Lake began what would become a two-phase approach in the attempt to eradicate zebra mussels, while conserving the warm-water fishery. Over the next several months, Highline Lake was lowered approximately 30 feet to expose areas along and near the shoreline to kill zebra mussels through the natural processes of desiccation and freezing. In March of 2023, CPW applied three separate treatments of EarthTech QZ, an EPA-registered copper-based molluscicide, to the lake.

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PHOTO CUTLINES:
Top: Highline Lake staff inspect rope floats for the swim beach line.
Bottom left: Zebra mussels found on several buoys throughout Highline Lake sit in a sample vial.
Bottom right: A single zebra mussel found on the bottom of a buoy at Highline Lake on Oct. 1.