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How the Southwest’s drought has led to a record-breaking increase in invasive mussels on boats coming into Colorado

Lake Powell’s low water levels have given invasive mussels an easier way to latch onto boats and hitchhike into Colorado

A Colorado Parks and Wildlife employee power-washes invasive mussels off a boat that was attempting to come into Navajo Reservoir, in southwest Colorado, from Lake Powell in Arizona. CPW has seen a record number of mussel-infested boats attempting to launch into Colorado bodies of water this year. (Photo courtesy of Colorado Parks and Wildlife)
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The intense drought in the Southwest is threatening Colorado water supplies beyond just the lack of rainfall.

State wildlife officials report a record number of boats carrying invasive mussels coming into Colorado from out of state. And the arid summer and winter could be to blame.

The main culprit is Lake Powell, whose low water levels have exposed more mussels — which have infested that body of water in Arizona — and made it easier for the invasive species to cling to boats and hitchhike out of state.

“An explosive quagga mussel population, coupled with lower water in Lake Powell, has resulted in boaters being more exposed to mussels than in past years,” said Elizabeth Brown, Colorado Parks and Wildlife’s invasive species coordinator. “Mussels typically live deeper in the water column, but when the water is low they are exposed on the rock walls and islands that previously were submerged.”

CPW inspectors have found a record 43 boats containing invasive mussels this year, 32 of which came from Lake Powell. The previous record was 26.

“Lake Powell is infested, and a lot of boaters, a lot of people from Colorado, haul their boats over there,” said Joe Lewandowski, a spokesman for Colorado Parks and Wildlife. “A lot of them are bringing them back at this time of year.”

The invasive quagga and zebra mussels can reproduce quickly and can clog drinking water infrastructure if they make their way into a lake or reservoir.

That makes the threat all the more urgent since water levels are low in western Colorado reservoirs and there isn’t much moisture forecast in the next few months. Simply put: There isn’t water to spare should a mussel problem arise. 

A boat with a pipe clogged with invasive mussels at Ridgeway Reservoir in southwest Colorado last year. (Photo courtesy of Colorado Parks and Wildlife)

Although Colorado has had some infestation scares in recent years, lakes and reservoirs still are clean because of a rigorous boat inspection program.

“They grow like crazy once they get a foothold,” Lewandowski said. “It’s very difficult to clean those out, if not impossible. They could really tighten the noose on boating in Colorado if we start getting these things popping up in reservoirs.”

CPW is asking people to make sure they thoroughly check their boats for signs of mussels. They are not always easily spotted on a boat’s hull and have been found on ropes, in live wells, on fishing gear, in buckets, on recreational equipment and on boat trailers.

“When people are leaving Lake Powell, they need to look in all the compartments and at all their gear,” Ed Keleher,  Switzer Lake State Park’s manager in Delta County, said in a statement.

The Colorado legislature voted this year to increase boating fees to help sustain CPW’s program fending off invasive mussels.