By Cam Fortems
Kamloops This Week
Behaviour of the North Thompson River as it peaks will help determine how many slaps are made to exposed legs, arms and necks this season.
“We’re hoping the river will peak in the next few days and next week we’ll be launching a massive campaign from Vavenby to Kamloops,” said BWP Consulting owner Cheryl Phippen, who conducts mosquito control for the Thompson-Nicola Regional District.
The river, which typically peaks in late May or early June, is days away from reaching its maximum volume and will then begin to decline, she predicted.
“The river is shooting straight up.”
The control program will be more effective if the river peaks only once, Phippen said.
BWP staff have already seeded snowmelt areas with a naturally occurring larvicide, including in Pinantan, Pritchard, Knutsford and Lac Le Jeune.
That program began on April 15.
“We finished up there,” Phippen said. “Now we’re waiting for the river to flood.”
Despite waiting for the river to peak before beginning the helicopter program, Phippen said some riverside areas that flooded earlier are already producing larvae, forcing early application of larvicide by air.
Once rivers peak, particularly the North Thompson, the program uses larvicide on areas of standing water left behind that become breeding areas for mosquitoes.
A helicopter is used for the river-based program.
The larvicide must also be applied so it coincides with the correct stage of larval development.
BWP uses a larvicide contained within kernels of corn.
The product, Btk, is a naturally occurring bacteria.
It has no known affect on humans, plants, honeybees, birds or beetles, according to the Ministry of Forests and Natural Resource Development.
Phippen said an ideal peak for the North Thompson is over two to three days, followed by a steady decline.
Using the helicopter, the company broadcasts the material over one to two days in key areas.
“And we hope it’s not pouring rain,” Phippen said.
A one-centimetre rise in the North Thompson River corresponds with a one-hectare area of fields flooding with water.
The South Thompson River peaks later and its rise and fall is steady and predictable.