Lake Powell boaters are among the most heavily monitored water recreationists in the West because their crafts are potential vectors for invasive mussels infesting Utah’s largest lake.

In an effort to avoid spread of the coronavirus, however, federal and state officials were not fully inspecting or decontaminating boats that have come off the lake since early April. That move paused Utah’s main defense against the spread of quagga mussels just as boating season shifts into gear.

These uninspected boats could pose a threat to Flaming Gorge National Recreation Area and other lakes if contaminated vessels move quagga mussels from Lake Powell into a new body of water.

Nearly 1,000 boats launched onto Lake Powell between April 1 and 6, when the ramps closed to any new launches, according to the Utah Division of Wildlife Resources. The agency is requiring owners of boats that came off the lake without being inspected to keep them in dry storage for at least 30 days before launching in another Utah lake, but officials acknowledge enforcement could be difficult.

“A certain part of our program depends on the boating public voluntarily complying,” said Nathan Owens, who runs DWR’s aquatic invasive species program. “We can’t be everywhere all at once.”

With the warming weather and growing enthusiasm for fishing, Utah lakes that remain open for boating are expected to see greater use in coming weeks.

“We are seeing much higher boating traffic at our local reservoirs than we normally would,” Owens said. “Part of it is people have cabin fever, and they want to go out. ... People have fewer options for places to go, so they all go to the same place.”

It takes just one boat

The Green River, backed up behind Flaming Gorge Dam, is one of those places. Meanwhile, Lake Powell is largely closed to boating, while nearly all Utah state parks that access reservoirs are open to everyone. Summit County’s Echo and Rockport state parks remain open to only in-county residents.

Native to the Caspian Sea, quagga and its cousin, the zebra mussel, are invaders introduced in the Great Lakes decades ago from freighters discharging their ballast tanks in North American waters. Cementing themselves in vast colonies onto any hard surfaces, these tiny mollusks disrupt ecosystems and damage infrastructure wherever they get established. Recreational boaters helped move them westward. They appeared in Lake Mead and Lake Powell several years ago.

(Courtesy file photo from National Park Service) Dropping water levels at Lake Powell expose invasive quagga mussels clinging to rock walls.

Coordinating with counterparts in neighboring states, Utah wildlife officials have gone to great lengths to keep quagga mussels confined to Powell, where they are proliferating. Those efforts have so far been successful, but it would take just one contaminated boat to unleash the quagga contagion on Flaming Gorge, Bear Lake or other bodies of water used for fishing and recreation. Because they have no natural checks on their populations, quagga mussels cannot be removed after they are established.

“Once the footprint of quagga infestation has been expanded," said former Salt Lake Tribune reporter Brett Prettyman of Trout Unlimited, "it exponentially increases the availability of it to spread even further,”

During the April 1-6 period, when inspections were suspended at Lake Powell, DWR officers recorded bow numbers of boats leaving without being inspected or decontaminated, according to Owens. Those numbers were entered into a database that officials could check when examining boats seeking to launch elsewhere.

“All were encouraged to drain their boats of all water,” Owens said. “That would eliminate 90% of the risk.”

Boaters will be subject to citations if they try launching before the 30-day wait, warned DWR spokeswoman Faith Heaton Jolley.

“We were informing boaters as they came off Powell,” she said. “Everyone has to do their part to prevent the spread of quagga. Everything has gotten more complicated with COVID-19 and social distancing.”

‘That would be a nightmare’

Under normal circumstances, the National Park Service, along with Utah and Arizona wildlife officials, inspects boats as they are towed from Lake Powell, ensuring their drain plugs are pulled and examining them for adult mussels attached to the hull and larval mussels in water holds. If quagga is found, the boat must either be decontaminated on the spot, using blasts of hot water, or spend time in dry storage to ensure any mussels are dead before the boat reenters uninfested waters.

“Larval quagga can live in residual water like in ballast tanks for up to 26 to 28 days,” Owens said, “so 30 days should provide enough time to kill anything left in residual water."

Trailered boats approaching ramps at Bear, Flaming Gorge, Deer Creek and other popular lakes are normally inspected and barred from launching if they appear to be carrying quagga.

Flaming Gorge is a particularly difficult lake to defend against a quagga introduction because it stretches over 90 miles with many places to launch boats. Some are developed ramps, but many are informal ramps in remote areas that cannot be staffed with inspectors. This season, Utah and Wyoming inspectors may station themselves on the highways surrounding the lake, so they can contact boaters on their way to the ramps.

“Our law enforcement section is stepping up and providing more invasive-species inspections, especially at the Gorge,” Owens said. “It’s the headwaters to a lot of other reservoirs. If that was infested, you would see the whole Green River infested. You are talking about hundreds of miles. That would be a nightmare for recreation and water infrastructure.”