Ruedi Reservoir, near Basalt, recorded less mussel-contaminated watercraft in 2024 than in 2023, likely due to additional inspection locations around the state.

“There’s new inspection points around the state access, so the big ones catch the ones that come from (Utah’s Lake) Powell,” said Basalt Mayor Pro-Tem Ryan Slack during an early November town council meeting.

During the meeting, Slack provided updates on the Ruedi Reservoir aquatic nuisance species (ANS) inspections for 2024 as the boating season ended around the state at the end of November. Inspections are performed in partnership with the U.S. Forest Service and Colorado Parks and Wildlife.

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The town of Basalt contributes $15,000 annually toward the inspections. In 2024, out of the 5,837 inspections that were conducted, 2,959 were entrance inspections, and 2,823 were outgoing inspections.

A total of 161 boats were decontaminated. This means these boats were dirty enough, typically at the motor, to trigger a decontamination of their vessel.

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Four boats were found with mussels. These boats had evidence of mussels, such as shells, fully-intact quagga, or zebra mussels.

The Roaring Fork Conservancy has set out about eight decontamination stations to clean gear, with one at Taylor Creek Outfitters and another at the Roaring Fork Conservancy. Despite conversations about paddleboarding beginning due to evidence of mussels being found in the lower Colorado, boats are still of more concern.

Boats hold water and have areas that do not dry out completely, whereas paddleboards and fishing equipment tend to dry out completely, which can kill the mussels.

In 2020, Ruedi Reservoir, in the Fryingpan River Valley, recorded Colorado’s highest number of intercepted boats carrying mussels. Officials said that is probably due to the reservoir’s relative proximity to Lake Powell, which has dealt with an invasive mussel infestation for years and became fully colonized by mussels in 2016, according to previous reporting from The Aspen Times.

Boats leaving Lake Powell are required to undergo inspection by the National Park Service, but many boats slip through. Nearly 70% of the mussel-infested boats intercepted in Colorado come from Lake Powell.

Ruedi is particularly vulnerable to mussels, according to the previous reporting. The turbines and pipes inside its hydroelectric dam are difficult to clean and could be destroyed if they are colonized. Mussels are also a filtering species, meaning they feed off the microinvertebrates, such as plankton, in their ecosystem. These microinvertebrates make up the base of the food chain, which helps sustain the renowned fishery downstream of the reservoir on the Fryingpan River.

Mussels also pose a high threat in Colorado because of the state’s position upstream of other watersheds. Scientists suspect that zebra and quagga mussels would have difficulty establishing in a high-elevation river, but it is still possible that they could be distributed downstream.

Quagga and zebra mussels are native to eastern Europe but have infested waters around the world. The creatures, each wrapped in a hard, sharp shell, cling to surfaces in fresh water and quickly breed. The larvae of these aquatic nuisance species — as they are designated by the state — have been detected in several Colorado reservoirs over the years.

“Looking at Highline, how long that’s been closed, you don’t want to go there,” Basalt Mayor David Knight said. The Government Highline Canal near Grand Junction was shut down for decontamination after the presence of zebra mussels was detected in July.

No adult zebra mussels have been found, only “veligers,” which are the free-floating larval stage of the mussel. The veligers can only be seen with a microscope. CPW has partnered with U.S. Fish and Wildlife and the U.S. Bureau of Reclamation to continue sampling in the areas with the goal of finding the source of the veligers.

“I’m all about continuing that education, even though it’s the winter time,” said CPW Northwest Region Public Information Officer Rachel Gonzalez.

“But now we’re starting to see the angling community taking advantage of the cooler weather, getting out there and fishing, so it’s not just about the boats, but it’s also about that angling gear too,” she added. “We want to make sure that we’re cleaning and drying and not taking potentially invasive species from one portion of the water to another.”