UPDATE: 4:30 p.m.
The B.C. River Forecast Centre has updated its Similkameen River flow forecast for the weekend, reducing the expected volume from around 990 cubic metres per second down to 660 m3/s.
It is not immediately clear how this may affect local flooding.
Osoyoos residents should expect the lake to rise to a little over the 917-foot mark at its peak later this week or on the weekend, according to on expert monitoring the situation.
About 200 local residents filled the Sonora Community Centre in Osoyoos Tuesday evening to hear from a lineup of various officials. That included municipal and regional district staff, staff from various provincial ministries and Brian Symonds from the International Joint Commission, which oversees cross-border water issues between the U.S. and Canada.
Symonds told the crowd the lake’s highest recorded level was from 1894 at 918.84 feet.
“If you think about where we are today, it’s a little over three feet higher. Now, I don’t think we’re going to get there, and in fact, I would be very surprised if we did,” Symonds said, adding the lake could reach the oft-mentioned 1972 level of 917 feet.
Symonds said the Similkameen River flow is expected to grow to around 990 cubic metres per second Friday night, about 57 m3/s higher than last week’s peak flow.
But more important is the duration of that peak. While last week’s flow peaked overnight before dropping back down, the next peak, expected to come late Friday, is forecast to plateau at its peak from Friday night to Sunday night.
A resident received applause from the crowd when she said she had noticed Okanagan Lake’s dam had been pre-emptively drained earlier this year in anticipation of floods, but had seen the Osoyoos Lake was sitting at 913 feet “for at least April and May.”
“When the lake was at 910-and-a-half (feet), the gates were fully open on the dam. You can’t let anymore water out at that level,” Symonds said. “It has to do with inflow, for sure. The gates are physically right out of the water.”
Another resident spoke up to ask why the inflow from the Okanagan River, which has dams controlling it, wasn’t held back to let the dam below Osoyoos Lake drain water in advance of the floods.
“The problem is they are going to get a lot of water coming into Okanagan Lake this year, later on,” Symonds said. “I know this isn’t the answer you want to hear, but you saw what happened last year. If they didn’t start drawing that lake this year, it would be worse — substantially worse — on Okanagan Lake than what it was.”
|Image: Environment Canada/Screengrab|
Symonds added that controlling the Okanagan River does not have as much of an impact; about 60 per cent of the water going into Osoyoos Lake from the Okanagan River is from tributaries flowing in below the dam in Penticton.
As well, the major inflow for the lake is the Similkameen, and numerous tributaries either flowing into the Similkameen, the lake or into the Okanagan River after the dams.
Shaun Reimer, who works the dams on the Okanagan River with the Ministry of Forests, Lands and Natural Resource Operations, pointed to 1999 as an example of a higher snowpack than this year’s that melted with no issues.
“It’s the timing and how quickly the snow is melting,” Reimer said. “We can never completely predict those things. To prepare for it every year for flooding, will that mean at the expense of fruits and some drought? And if we draw down all these lakes that we don’t know what we’re going to get into in terms of drought, and it’s hard to turn the ship late in the day.”
Town of Osoyoos chief administrative officer Barry Romanko did say there were some ways that the public could help, as groundwater and flood water adds to wastewater storage, causing some trouble for the system.
“We’re asking that all residents consider decreasing their use of the sewer system, and I’ll leave it to your creativity in terms of how you do that,” Romanko said.
“A two-minute shower instead of a 10-minute shower. All of those types of things will help the community in its entirety deal with this during the course of the period of time that we have to deal with this particular issue.”