Biologists are confident schools of perch and smallmouth bass in a small lake near Salmon Arm will suffer the same fate their cousins in other nearby Shuswap lakes have met.
And while the prospect of a massive fish kill usually sends shudders of regret up the spines of those who care about such things, this die-off will do the opposite.
Kamloops fisheries biologist Steve Maricle said a proposed kill-off of Gardom Lake near Enderby in early October will be his department's most ambitious lake "treatment" project yet.
It will be the fifth lake in three years that Ministry of Environment biologists hit with rotenone, an organic poison almost instantly lethal to fish.
Gardom Lake has been overrun in recent years by illegally introduced yellow perch and smallmouth bass. The species are native to eastern Canada - not B.C.
It's believed the spiny-ray invaders have been brought to Shuswap-area lakes by anglers wanting to create new sport fishing opportunities.
What the illegal transplanters create, however, are environmental messes.
Maricle said perch, bass and other eastern species such as sunfish have significant impact on lakes where they establish populations, wiping out native species of trout and changing the lake's ecosystems. Perch and bass have no natural predators in B.C. They are also prolific breeders, causing their numbers to swell unnaturally. Insects disappear, affecting everything from populations of amphibians and reptiles to birds.
Biologists also fear the invaders will escape to the Shuswap Lake system, where they could pose a serious risk to wild salmon and trout stocks.
The Environment Ministry has been aggressively working to eradicate perch and bass in area lakes in recent years before such an escape takes place. Skmana, Little Skmana, Nellies and Forrest lakes have already been poisoned.
Maricle said this project is complicated by the fact there are year-round residents on the lake who depend on it for their water, including an active dairy farm that draws nearly 50,000 litres a day. All residents will be unable to use lake water for at least four weeks.
Maricle said arrangements are being made to provide alternative water supplies. Most residents will have their water trucked in, but it's possible the farm will be supplied from a well the ministry will drill specifically for the purpose.
The cost of supplying the water to the residents will top $200,000. All together, the Gardom Lake project will cost about $500,000, he said. All the money will come from the Habitat Conservation Trust Fund, a fund supplied by surcharges collected from hunting and fishing licences.
Maricle said four more lakes in the Turtle Valley near Chase will be on the treatment list next year. All those lakes contain perch, smallmouth and largemouth bass and sunfish.
The ministry has had four public meetings with Gardom Lake residents in recent months. While some people were initially opposed, they have realized the impact perch and bass have had and are now on side.
Sporting groups in the area are also on board, he said. The lake was closed to sport fishing this season to keep it from becoming a source of fish for more illegal introductions.
Maricle said the wiped-out lakes will eventually be restocked with trout. He hopes the word is out about the impact such transplanting can have and it won't happen again.
Kamloops conservation officer Steve Waslick said a $25,000 reward remains in effect for information leading to convictions against those responsible.
Despite the reward, authorities have never received a single piece of useful information about those responsible.
Waslick said there have been no new reports of perch elsewhere in the area. He hopes that means whoever did the moving in the first place has moved on, but he's mindful of the fact transplanting perch is not rocket science.
"It's so easy to do. With a five-gallon pail, you can move perch," he said. "The fact there has been no new infestations is a good sign."