Following months of concern and worry, fisheries biologists with the Nevada Department of Wildlife have finally received some good news in the ongoing saga of the invasive quagga mussel.

Plankton samples collected from Wildhorse Reservoir in Elko County have tested negative for both quagga and zebra mussel larvae.

Experts at the Portland State University Center for Lakes and Reservoirs processed the sample, which was collected in June by department fisheries biologists. Scientists were looking for mussel DNA to determine whether the mollusks were present in Wildhorse.

Samples from other Nevada waters have yet to be processed, but this early result from Wildhorse has given department and other agencies hope that the results for those waters could be the same.

"Our biggest concern is protecting watersheds and protecting ecosystems, especially sport fisheries," said Kim Tisdale, supervising fisheries biologist in the department's Western Region. "Anytime you have an aquatic nuisance species, like the quagga mussel, it can attack the ecosystem and have dramatic impacts on the fishery."

A relative of the zebra mussel, the quagga is a prolific breeder, with a single mature female capable of releasing a million eggs per season.

Over time these mussels can affect recreational boats, water supplies, agricultural irrigation and water quality.

"The quagga is a prodigious filter feeder capable of removing phytoplankton and other particles in the water to a point of altering an entire ecosystem. This can lead to an increase in aquatic plant species and have serious impacts on the sports fisheries," said Jeff Peterson of the department.

Subsequent to their discovery in the lower Colorado River System, invasive quagga mussels were also found in the Lake Mead Fish Hatchery. That discovery created an extra level of anxiety among fisheries experts not only from Nevada, but also from surrounding states.

Their concern was that mussels might have been inadvertently moved from the hatchery to interior waters during trout stocking operations in 2006.

One of those waters is Wildhorse, which ultimately drains into the Columbia River Basin. Other waters of concern include Southfork Reservoir, the Ruby Marshes and Topaz Lake in northern Nevada.

To the south, reservoirs at the Kirch Wildlife Management Area, Eagle Valley and Echo Canyon are also on the list. Although this doesn't necessarily mean that the mussel was introduced into these waters, it does greatly increase the chances.

"Department biologists are closely monitoring these and other bodies of water for both settled sub-adults and the free-floating larval veligers, " Peterson said. "The department is also urging boaters from all waters to take positive action to not only avoid the spread of these mussels, but all aquatic species that might have negative impacts on area waters."

Quagga mussels can survive in small pockets of water and they are capable of enduring dry conditions for as long as five days or more.

Boaters and anglers are being asked to take a few minutes to thoroughly inspect and clean their boats, trailers, canoes, waders, float tubes, and other related gear before leaving one body of water and heading to another.

This applies not only to Lake Mead, Mohave and the Colorado River system, but also to every other body of water in the state.

The cleaning steps should include:

Drain the water from motor, live well, and bilge and flush with hot soapy water or a 5 percent solution of household bleach.

Remove any visible mud, plants, fish or animals from all gear. This is includes fishing rods and reels, nets, waders, float tubes, tackle boxes and any other item that comes in contact with the water or shoreline.

Wash all exposed surfaces with hot, soapy water or a 5 percent solution of household bleach.

Air-dry equipment for at least five days.