’Scientific look‘ needed at pontoon sinking plan

More scientific research should be done into the possible environmental impact of sinking the old bridge pontoons, Kelowna city council heard Monday.

Anna Warwick Sears, executive director of the Okanagan Basin Water Board, said there should be a “rigorous scientific look” into the question of whether submerging the concrete pontoons into the deepest part of the lake could affect water quality.

She acknowledged she‘s not an expert in the matter, in response to a question from Coun. Norm Letnick. But at the very least, she said, if the sinking does go ahead, it should be done at a time of the year when there isn‘t much vertical movement in the lake.

The lake “turns over” twice a year, Sears said.

Sinking the pontoons when there isn‘t much vertical water movement could lessen the chance that sediment from the lake bottom is “re-mobilized” and gets kicked up, to find its way to municipal intake pipes.

The provincial government has said the planned sinking of the old concrete pontoons poses no risk, but a legal challenge has arisen from opponents to the plan.

The Okanagan Basin Water Board is mainly concerned with controlling the spread of weeds in the lake, but has branched out in recent years to examine many issues relating to the supply and management of water resources in the Valley.

The City of Kelowna contributes about $550,000 a year toward its operations.