Eurasian water-milfoil (Myriophyllum spicatum). (Contributed)

Climate change brings higher numbers of invasive aquatic plants in Okanagan

Eurasian watermilfoil thrives in warmer waters, and the water board is expecting it to get worse

A warming planet is allowing invasive plants to thrive in Okanagan lakes.

James Littley, operations and grants manager with the Okanagan Basin Water Board, said milfoil thrives and spreads in warmer waters, which means more money spent to keep the invasive weed at bay.

Eurasian watermilfoil is a very aggressive invasive plant that kills native species, first identified in the Vernon area of Okanagan Lake in 1970. By 1974, the plant was well established in the main lakes of the Okanagan.

Environment Canada scientists recently released a report stating that Canada is warming twice as fast as the rest of the world.

The country is also not on track to hit its 2030 target in reducing greenhouse gases.

READ MORE: Canada’s failure to fight climate change ‘disturbing,’ environment watchdog says

According to dated collected from Summerland’s weather station between 1916 to 2016, winter temperatures have increased by 1.6 C.

Erratic weather patterns are also more common in recent years, according to data compiled by Denise Neilsen, a former research scientist at the science and technology branch of Agriculture and Agri-Food Canada.

READ MORE: Canada heating up faster than rest of world: Report

“With milfoil, the more hot summers we have and the more the lake stays warmer, the more milfoil we’ll see and the faster it will grow. Ideal conditions for milfoil are bright, sunny and hot with warm water temperatures,” Littley said.

READ MORE: Collaborating with First Nations in B.C. to combat climate change

“Right now we’re becoming more and more restricted on our milfoil till program because of concerns around (endangered mussel species.)”

The Okanagan Basin Water Board uses a rototiller in the winter to remove the plant from the bottom of the lake, so it dies in the cold water temperatures.

In the summer, a harvester cuts off the tops of the weed where they’re taken and composted, as part of its program to control milfoil numbers.

The best way to deal with the plant is by removing it from the lakebed, Littley said.

”If we have to switch to the summer harvesting program, there’s not a lot we can really do. We’ll have to concentrate our efforts solely to public beaches and taxes will go up because we’ll have to purchase new equipment and hire new operators and be out there for longer.”

READ MORE: Kelowna: UBCO economist and water stewardship members question ALR change

More milfoil also means increased incidents of blue-green toxic algae blooms.

Invasive zebra and quagga mussels, which haven’t yet been seen in the Okanagan, also thrive and reproduce more in warmer waters, and grow on milfoil, he said.

Floods also provide nutrients to the water and contribute to thriving milfoil numbers.

The cost of the milfoil containment program in the Okanagan Valley is between $600,000 to $800,000 a year, with the expectation that the warming of Okanagan lakes due to climate change will increase that cost, Littley said.

Editor’s note: A previous version of this story stated the milfoil containment program cost $60,000 to $80,000 a year, when it is actually $600,000 to $800,000.

@carliberry_
carli.berry@kelownacapnews.com

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