By Richard McGuire
Special to the Chronicle
Flooding around Osoyoos Lake over the weekend forced the evacuation of numerous properties as the lake’s level came within inches of the record flood in 1972.
The lake reached a high of 916.45 feet above sea level at 11:30 a.m. Saturday before dropping by almost five inches as of Monday afternoon.
But officials warn that “extremely high temperatures” for this time of year could accelerate snow-melting heading into this week, triggering more flooding.
“The Regional District of Okanagan-Similkameen (RDOS) is preparing for high water levels in the Similkameen River and Osoyoos Lake later this week,” the Town of Osoyoos and the RDOS said in a bulletin dated May 12, but issued Monday morning.
“Warm temperatures and a high snowpack will lead to rising water, which is expected from today with an estimated peak Friday,” the bulletin continued.
The town planned a public information meeting for Tuesday, May 15 at 6:30 p.m. at the Sonora Community Centre, along with representatives from the RDOS and provincial government.
Residents were told to expect updates on the flooding, information on protection and information on support agencies, the town said in another information bulletin.
Residents from 23 properties on Harbour Key Drive and Solana Key Court, as well as the Coast Osoyoos Beach Hotel were initially ordered to evacuate late Thursday.
Then on Friday, a further 30 properties were ordered to evacuate, mostly at Harbour Key and Solana Key. But also included were five properties on Cottonwood Drive, including the Poplars Motel, and one home on Kingfisher Drive next to Legion Beach.
Meanwhile, 17 properties in RDOS rural Osoyoos Electoral Area A were also evacuated as of Saturday, including a number of properties at Willow Beach, which is largely inundated.
Volunteers were busy filling sandbags at the boat trailer parking lot on Highway 3 late last week and into the weekend, as residents and volunteers built dikes around low-lying homes and properties.
Loads of pre-filled sandbags were also trucked into Osoyoos.
The lake rose very rapidly between Saturday May 5 and last Friday, climbing more than three feet during that time. The quick rise left many residents unprepared. Then from Friday afternoon until the end of Saturday, the lake level hovered in the 935-to-945-foot range, before slowly dropping on Sunday.
Despite the slight drop of Osoyoos Lake since Saturday, the Similkameen River is again rising, though it is far from its peak reached Thursday night.
Although the Similkameen River doesn’t flow directly into Osoyoos Lake, it can impede the outflow of the lake’s water by acting as a dam where it meets the Okanogan River just below Oroville, Washington.
This means that activity on the Similkameen River can be a predictor of future rises and falls in the level of Osoyoos Lake.
At 9:30 p.m. on Thursday, the Similkameen reached a discharge rate of 32,300 cubic feet per second (cfs) as measured at Nighthawk, Washington for the U.S. Geological Survey.
It fell as low as 22,800 cfs early Sunday before starting to rise again. By Tuesday morning, it was back up to 26,000 cfs.
Meanwhile the RDOS has warned some residents in the Hedley and Similkameen River area currently under evacuation alert that they should prepare for an evacuation order for some areas in the next few says.
“The Similkameen River collects water from as far away as Manning Park and the Coquihalla Highway,” the Town of Osoyoos and RDOS said in a bulletin. “Melt water from these mountains is predicted to rise with warm weather forecasted. The Similkameen River, and its tributaries such as the Tulameen River, have already created problems including the closure of Highway 3 and evacuation of homes.”
In a conference call with media on Monday, Dave Campbell, head of the B.C. River Forecast Centre, also warned about the chance of renewed flooding due to warmer weather expected this week.
Temperatures over the past three weeks have been generally six degrees above normal in many parts of the province, he said.
Snow at lower elevations has now melted, he said, and at middle elevations between half and two thirds has melted. At higher elevations, however, only between 10 and 30 per cent of the snow has melted so far, Campbell added.
This change from low and middle to upper-elevation snow melt is creating a transition in terms of the rivers that are most susceptible to flood risk in the coming days, he said.
Campbell mentioned the Okanagan and Similkameen valleys as being among the areas of the province that have already experienced flooding, but could see more floods this week.
The Town of Osoyoos declared a State of Local Emergency last Wednesday and at the same time the RDOS made the same declaration for Electoral Area “A”, rural Osoyoos.
The State of Local Emergency gives local authorities emergency powers to order evacuations, prohibit travel and enter private property when an emergency threatens lives, property or the environment within the local authority’s jurisdiction.