Don’t move a mussel: Boaters key to preventing dangerous infestation in Colorado |

Don’t move a mussel: Boaters key to preventing dangerous infestation in Colorado

Signage at Elkhead Reservoir reminds boaters of the proper protocol to avoid transmission of zebra or quagga mussels between bodies of water.
Samantha Johnston

Two of the most ominous Aquatic Nuisance Species threatening Colorado lakes and reservoirs are most easily prevented by boaters who follow simple guidelines before they enter and after they exit the water.

The zebra and quagga mussels are the most concerning species to state officials.

“Colorado is under significant threat right now,” Colorado Parks and Wildlife Northwest Regional Public Information Officer Mike Porras said earlier this month. “If just one mussel escapes detection, it could lead to the first infestation in the state.”

Colorado Parks and Wildlife Resources

Boaters Guide to Aquatic Nuisance Species (ANS) Inspections

Clean, Drain and Dry Recommendations

2019 Colorado Statewide Watercraft and Inspection and Decontamination Stations

Colorado Parks and Wildlife Boat ANS Inspection and Decontamination

Colorado Parks and Wildlife Invasive Species Resources & Publications

CPW issued a news release in early July that Colorado’s boat inspectors are overwhelmed by mussel-infested boats. As of early July, inspectors had intercepted 51 boats infested with mussels this year, already on par with the total from 2018.

“Small amounts of water that come in contact with the species are sufficient to transport the larval form of the mussel,” he said Tuesday.

While mussels have not been detected anywhere in Colorado, the state is no longer considered 100% mussel-free because quagga mussel larvae were discovered in Green Mountain Reservoir in 2017. The issue rose to a priority level with state legislators at that time, and they wrote a letter to then-Interior Secretary Ryan Zinke.

“We urge you to respond rapidly, deploy available resources and work with the state and local communities to prevent this initial detection from growing into a full infestation,” the letter stated.

In 2006, Virginia Department of Game and Inland Fisheries successfully eradicated zebra mussels from the Millbrook Quarry. In Colorado, eradication of the species once it is present is nearly impossible with the current technology, Walters said.

“To complete the eradication (in Virginia), it took 174,000 gallons of potassium chloride solution being injected into the quarry over a three-week period,” he said. “It took more than $400,000 to treat that 12-acre quarry.”

In comparison, Elkhead Reservoir has a total capacity of 13,700 acre feet of water — an area that could hold the Millbrook Quarry more than 1,100 times over.

Even if cost and technology weren’t a factor, the flow of water in and out of Colorado reservoirs and lakes makes eradication unrealistic, Walters said.

While there are no current causes of concern at Elkhead Reservoir, vigilance is necessary because so many boats are coming back to Colorado from areas with infested waters. Interceptions are happening nearly daily and many of those boats are coming from Lake Powell, Walters said.

“If you’re a boater and you’ve been to Powell, you’ve seen how devastating the infestation is,” Porras said. “If one boat were to launch illegally at Elkhead and mussels get into the water, they will essentially end up in the situation like we’ve seen at Powell. Once you get them, there’s no going back.”

Zebra mussels are native to the Black, Caspian and Azov seas of Eastern Europe, but were discovered in the Great Lakes in 1988 and have since spread to 33 states in the United States according to CPW. Quagga mussels are native to Dnieper River Drainage in the Ukraine and were discovered in the Great Lakes in 1989 and have since spread to 27 states.

While there are several issues with mussel infestations, the big three are trouble for recreation, ecology and economics.

“They take over lakes and reservoirs and cover shorelines, rocks, docks … you can’t walk on the sandy beach anymore because you are walking on razor-sharp shells,” Walters said. “As water levels fall, it exposes millions of rotting mussels, which creates a rotting smell and unsafe conditions.”

From an ecological perspective, mussels are filter feeders, which means that they filter out nutrients and phytoplankton in the water at a rate of up to one liter of water per day by a single mussel, according to Walters. If millions of mussels are filtering up to a liter per day, they are essentially consuming the aquatic food chain that supports the rest of the water body’s ecosystem.

Infested waters are also less attractive to visitors and can wreak havoc on hydroelectric infrastructures, which come at a cost that will eventually trickle down to the consumer, according to Walters.

“Cleaning dams and water distribution pipes … power and water companies aren’t just going to absorb those costs,” Walters said.

The most common transmission of these nuisance species are boaters. Colorado is a mandatory boat inspection state, which means that all motorized watercraft are required to be inspected by state certified personnel.

According to the CPW website, inspections are mandatory prior to launching in any Colorado water after boating in a different state; upon exiting any water that is positive for an invasive species; any time an inspection is required prior to entering or exiting a water body in Colorado.

“There’s not one area that’s more susceptible than others,” Porras said. “All it takes is one boat with a few mussels attached, and it’s over.”

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