LOMA, Colorado — Colorado Parks and Wildlife announced it has finalized a new plan to eradicate mussels found in Highline Lake State Park.
The agency said five adult zebra mussels were found while removing buoys at the western Colorado lake Oct. 1.
The plan will be a phased approach with the first beginning in late 2023, with the second phase taking place gradually over 2024.
During the first phase, Colorado Parks and Wildlife (CPW) will apply a higher concentration of EarthTec QZ, the same EPA-registered copper-based molluscicide that was applied to the lake in March, in order to suppress the population.
In early 2024, CPW will begin slowly lowering Highline Lake with an complete emptying of the lake by the end of the year. With the lower water levels, CPW said Highline Lake will be closed to all motorized boating for the 2024 boating season.
“We did not make this decision lightly or in haste,” said CPW's Invasive Species Program Manager Robert Walters. “Over the past year we have had numerous discussions with CPW’s Northwest Region aquatic, regional, and state park staff, and we have come up with a plan that builds upon that work that was performed last spring.”
Emergency fish salvage
CPW said it cannot move fish out of Highline Lake into other waters prior to draining due to the risk of moving viable mussels on or inside fish. In this case, the only option is to reduce fish loss by removing bag and possession limits.
An emergency fish salvage is now in place at Highline Lake until further notice. CPW said 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 from the shoreline utilizing the lawful angling methods currently allowed at the lake. CPW said all fish must be dead prior to transport away from the lake.
“While the efforts in early 2023 did not achieve our ultimate goal of eradicating zebra mussels, we believe it helped to keep population numbers at a manageable level,” said Walters. “A single female zebra mussel can produce more than 30,000 eggs per reproductive cycle. Any mussel we can keep from reproducing in the immediate future increases the probability of our success next fall.”
“We understand that this isn’t ideal for our boating and angling community,” said Alan Martinez, Highline Lake State Park Manager. “What we hope is that people see this and understand how serious this problem is, and that it can be avoided by simply cleaning, draining, and drying your boat or any equipment that comes in contact with the water in between each and every use.”
“Eradication of zebra mussels has been, and will continue to be, our goal at Highline Lake,” said Ben Felt, Northwest Region Senior Aquatic Biologist. "Earlier this year, we pursued an option that had the potential to eradicate the mussels while maintaining the fishery. Based on this recent discovery, we recognize achieving both is not feasible. To do nothing would be detrimental to Highline Lake and would put fisheries across the state at risk. CPW is committed to rebuilding the Highline Lake fishery once the zebra mussel eradication project is complete."
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