The invasive aquatic weed, Eurasian Watermilfoil has made an early appearance in valley lakes. As a result, calls to the Okanagan Basin Water Board have already started.
“Usually we are just starting to survey the lakes to see where the milfoil is growing under the water and where we need to start working,” said James Littley, operations and grants manager for the water board.
He added that the first call this year came in last week.
In the summer of 1972, the provincial government partnered with the water board and started an intensive program to remove the newly introduced, invasive milfoil from Okanagan lakes.
Early efforts focused on harvesting the weed, using everything from floating barges to hand-scythes and pitch forks.
The program was handed over to the water board in 1998 and more recent control efforts have included research into breeding special weevils to eat the weed.
Today, the water board employs three operators who spend thousands of hours on the water annually to control the volume of the invader at our beaches, boat launches and marinas, at more than 200 sites in the valley.
Economically, uncontrolled milfoil has negative effects on tourism, and studies have shown that thick milfoil mats can lower lakefront property values by as much as 19 per cent, Littley said.
Environmentally, milfoil robs oxygen from the water, increases water temperature, slows the flow at the mouths of rivers, and increases polluting nutrients in the water.
It has also been linked to fish kills and loss of biodiversity.
Last year, a provincial study found the primary factor reducing the flow of Okanagan River out of Vaseaux Lake was milfoil growth.
“The Okanagan River there runs at about 10,000 litres per second in the summer — enough to fill an Olympic swimming pool in around four minutes — and milfoil is slowing it down,” Littley said.
Most milfoil in Okanagan lakes is controlled. Wood, Kalamalka, Okanagan, Skaha and Osoyoos all receive regular milfoil treatment through the water board’s program.
In the winter, milfoil operators rototill the weed while it’s dormant.
The roots are then left to freeze and die.
In the summer, the weed is harvested or mowed two metres below the surface and collected, then trucked to local gardens and orchards for fertilizer.
The program takes into account fish and other species habitats, spawning seasons, sensitive plants, at-risk animals, and special events like triathlons.
“This year, the combination of the early snow melt and the record warm temperatures seem to have created perfect conditions for the milfoil to grow early,” Littley said.
“We spent extra time on the water over the winter trying to get ahead of the summer growing season, but we just can’t compete with the changing climate.”
The threat now is if zebra and quagga mussels get into the Okanagan.
The invasive mussels are voracious water filters, allowing light to penetrate much deeper and increasing the habitat for milfoil.
The public can prevent the spread of both species by remembering to clean, drain, and dry our boats and other water equipment.
Now in its 41st year, the program has cost a total of over $18 million.
“This is a drop in the bucket of what the next invasive could cost,” said Littley.