Increasing the flow out of Okanagan Lake at Penticton is expected to start soon in an effort to prevent flooding this year.

(STEVE ARSTAD - REPORTER / iNFOnews.ca)

KELOWNA - This is the time of year when Shaun Reimer’s thinking cap starts to really heat up.

Reimer’s title is Section Head, Public Safety and Protection with the provincial government but in simpler terms, he’s the man who determines how much water runs out of Okanagan Lake at Penticton – as well as managing other water control structures along the Okanagan River.

“Right now, we’re basically trying to hit our normal target level,” he said. “Over the course of the early winter we try to keep Okanagan Lake where it is right now.”

After two consecutive years of Okanagan Lake flooding — and a high ground water table — all eyes are on him to accurately predict the future to avoid another flood, and still protect against drought. 

He monitors all kinds of scientific data but the key information starts coming in Feb. 1 with numerous snowpack readings. These don’t just measure the depth of snow in the hills, but the water content of that snow.

That means it's about now that he starts drawing down Okanagan Lake in anticipation of the spring runoff.

“Okanagan Lake is the big driver,” Reimer said. “The other lakes you can bring into balance easily. Okanagan Lake is sort of the big ship to steer. You have to start making those changes earlier.”

In 2017, the snowpack was near normal but heavy spring rains caused extensive flooding.

“Last year, we had an almost record setting snowpack, at least for some parts of the year, so we drew down the lake very significantly,” Reimer said. “This year, right now, we’re not looking at a big snowpack. The next little while will tell the tale in terms of which way the winter is going to go.”

He expects to be a couple of centimetres above his target level by the end of January. He can easily make that up. He can drop Okanagan Lake by 1.5 to 1.75 cm a day without a serious impact downstream. Any more than that can cause flooding.

Even though the Okanagan River is mostly channelized almost to Osoyoos Lake, high river levels can cause culverts to back up and water to pool outside the dikes.

While the snow and rain patterns change every year, Reimer is troubled by the fact that the runoff has come much earlier in recent years.

“Generally, the lake peaked in early July,” he said. “Last year and in 2017, we peaked at the beginning of June. In 2017, if we had peaked at the beginning of July, I would have had 30 days there, or even 20 days, to remove that water. We (Okanagan Lake) would have been a foot lower.”

While he will soon start drawing down the level of Okanagan Lake, he has to balance the risk of flooding with the possibility of drought.

There was a three-year drought from 1929 through 1931 where only about one metre of water flowed into the lake over those three years. That compares to about 1.5 metres in May 2017 alone.

“A one-year drought is something manageable,” Reimer said. “When you get into a two or three-year drought, the potential economic hit is really significant.”

If the Okanagan was hit with a three-year drought, the economic impact would be in the hundreds of millions of dollars, he predicted, due to such things as orchards and vineyards dying and tourism dropping.

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