Photo: Chelsey Mutter

Kalamalka Lake seen from the Rail Trail in 2024.

As reservoir levels remain low in the Greater Vernon Water system, the Regional District of North Okanagan is trying to avoid the need for a city-wide water quality advisory.

Zee Marcolin, RDNO general manager of utilities, recently informed the Greater Vernon Advisory Committee that the system is beginning to see turbidity in the water. An early freshet, milfoil rising/removal, and low water levels mean anyone who's water is supplied by Kal Lake might need to be put on a water-quality advisory if turbidity gets too much.

In an attempt to avoid that, the RDNO is working with the Okanagan Basin Water Board and has reduced the amount of milfoil tiling on Kal Lake. The OBWB will be rototilling 2 to 3 times a week instead of the usual 5 times a week.

Marcolin explained to Castanet that rototilling causes a temporary spike in turbidity in the lake, as the machine pulls up weed roots mixing fine soil with the water.

"It takes 6 hours for RDNO to see the disturbance and lasts for about 6 to 10 hours for the highest spike to drop but then a few days for the base turbidity to completely return to normal so that over 5 days, the base turbidity has built to a level that will force GVW to issue a Water Quality Advisory (WQA)," said Marcolin.

"By OBWB rototilling for 2 to 3 days a week, it allows the base turbidity to return to very low levels and still get the job completed without causing GVW to issue a WQA."

If the milfoil was not removed then it would die off in the fall or winter, and the dead vegetation would rot and negatively impact water quality. The organics would cause taste and odour issues as well as provide nutrients for algae growth.

Milfoil is an infestation that can impact lake usage.

“Uncontrolled Eurasian water milfoil infestation can interfere with opportunities for water-based recreational activities, including motor boating, water skiing, sailing, swimming, and shore-based angling”, says the OBWB on its website.