Wildlife officials recieved word from a Bureau of Reclamation lab in Colorado late last week that samples taken from Pelican Lake and Red Fleet Reservoir in the Uintah Basin and at Midview Reservoir on Ute Tribal Lands tested positive for the larval form of what could be zebra or quagga mussels.

Further testing on the larvae DNA will reveal which of the exotic and invasive trouble makers have migrated to Utah, although there is a chance the creature spotted under the micrscopes in Denver could be something other than the mussels. The DNA test results won't be available until the end of this week, at the earliest.

"It is possible that it won't bear out to be these critters. We use two methodologies to confirm an infestation because this is a big deal," said Larry Dalton, aquatic nuisance species coordinator for the Utah Division of Wildife Resources. "In the interim, we are taking the appropriate steps of trying to contain them."

Zebra and quagga mussels were brought to North America from Europe by ship and introduced in the Great Lakes about 20 years ago. The tiny mussels reproduce rapidly and pose a threat to fish by reducing plankton. The mussels build huge colonies and can threaten dam operations, culinary water projects and boats of all sizes.

They are difficult and expensive to remove from boats and docks and nearly impossible to eradicate when in a lake or reservoir.

"We have shifted to a containment mode," said Roger Schneidervin, the Division of Wildlife Resource's regional fisheries director in Vernal. "We will be running boat spraying shifts from day break to to dark daily asking people if we can clean their boats as they leave Red Fleet and Pelican."

High pressure sprayers are used to clean the exterior of the boat and hot water is pumped through the live well and bilge system of boats as part of the process. Ute Tribe officials will be operating their own sprayer at Midview.

Forty-one biologists and technicians are monitoring boats launching across Utah as part of the DWR's aquatic nuisance species team. The effort to keep exotic species out of Utah was funded by a legislative appropriation of $2.5 million.

Dalton said the aquatic invasive team has had more than 50,000 interactions with boaters this summer and performed 800 decontaminations.

"People don't tell us no once they understand the risk," he said.

In an effort to stop the possible spread to other Uintah Basin waters, DWR officials were on hand this weekend during the annual Starvation Classic walleye fishing tournament at Starvation Reservoir. They asked all boaters, including those not fishing in the tournament, if they had recently had their vessel in either Pelican or Red Fleet. One boat was treated and allowed to enter the water.

"We have just added Pelican and Red Fleet to the list of waters we are already asking people about," Schneidervin said.

At every spray station, boaters are asked if they have been at Lake Powell, Lake Mead (Nevada) or any waters in Colorado. If so, the boat gets treated.

Lake Powell was the first Utah water to be identified as carrying the mussels a year ago, but further tests showed the first sample was a false-positive for the mussels, which is what DWR bioligists hope will happen with the samples from Pelican, Red Fleet and Midview (also known as Boreham).

A mussel scare also occurred at Flaming Gorge in June when a boat bought in Minnesota and launched at the large reservoir on the Utah/Wyoming border was pulled back for engine work. The mechanic noticed mussels attached to the boat and contacted wildlife officials. All of the mussel bodies attached to the boat were dead and containation is believed to have been avoided.

Schneidervin visited Pelican Lake Saturday looking for adult forms of the mussels.

"I looked under rocks and in vegetation, all the places you would expect to see them and I couldn't find anything even suspect by its shape that looked like a quagga or zebra mussel," he said. "That doesn't mean they aren't there. They are famous for population explosions."

He isn't too worried about the impact the mussels could have on a place like Pelican - which is small at less than a mile across and only 10-feet deep - because it is so productive. But if the mussels hit Flaming Gorge, they could easily wipe out the already delicate kokanee salmon population and impact the popular lake trout fishing.

"If Pelican is that hot [with mussels], it will be miraculous if other places in the northeastern region like Stravation, Steinaker and Flaming Gorge don't also show up as positive," Schneidervin said.

Strawberry Reservoir, Utah's most popular trout fishery, is another nearby water that could be affected by a mussel invasion.

"These mussels rob the food right out of the mouth of the fish by eating the plankton," Dalton said. At Lake Michigan they saw a 95 percent decrease in the lake trout population in 10 years. This is a major threat."

BRETT PRETTYMAN can be contacted at brettp@sltrib.com or 801-257-8902.