SALEM &

It's almost as if the cavalry threw poison down the homesteaders' well.




In April and May 2006, more than 34,000 trout from Nevada's Lake Mead Hatchery were planted in northwestern Nevada's Wildhorse Reservoir.




And along with the trout, hundreds of gallons of water &

potentially contaminated with microscopic quagga mussel larvae known as veligers &

were added to the reservoir.




Wildhorse is the headwater of the Owyhee River, which feeds into the Snake River, which runs into the Columbia River.




"We knew that boaters were going to transport (water). We knew that boaters were moving," said Mark Sytsma, the director of the Center for Lakes and Reservoirs at Portland State University. "But we just never had any idea that there would be massive transfers of water from Lake Mead to the Columbia Basin."




Quaggas and their cousin the zebra mussel are two of the most-feared invasive species in the Pacific Northwest, said Sam Chan, an aquatic ecosystem health educator with Oregon State University's Sea Grant Extension Program in Corvallis.




As soon as officials in Oregon found out about the potential for contamination, extensive monitoring was set up at the reservoir and downstream.




"We've sampled Wildhorse for the juveniles. And we've looked all over for the adults, and so far we haven't found anything," Sytsma said.




But because quaggas were in Lake Mead for several years before those were detected, sampling and surveys will continue.




"Now that one season of monitoring is completed, and nothing's been detected, I think we can breathe a little bit easier," said Paul Heimowitz, the aquatic invasive species and research coordinator for U.S. Fish and Wildlife Service in Portland. "But it's going to take monitoring over a number of years ... Just like cancer, you can't just assume that once you think you're safe that you can stop checking. You just have to be very vigilant and watching and constantly checking and ready to act quickly if something shows up."




Sytsma said states downstream from Wildhorse may have caught a break because of standard hatchery precautions used in moving and stocking fish.




"They do take some precautions when they transport fish," he said. "Like for an example, they add salt to the water. So there's some reason to be optimistic that if there were quaggas in the water that they were transporting the fish in, they died.




"At least that's a thin thread of hopeful thinking that we're hanging on to," he said.