The Zosel Dam in Oroville, WA helps to maintain the level of Osoyoos Lake, but it becomes ineffective when water in the Similkameen River is high and backs up the Okanogan River. Water flow in the Similkameen peaked over the weekend, but has since come down. It has been increasing again since early Wednesday. (Richard McGuire file photo)
With Osoyoos Lake’s level now surpassing 913 feet above sea level and with storms expected to cause more flooding to the north, the Town of Osoyoos is warning residents and businesses to be proactive about possible floods.
“It is uncertain how or if the situations further up the valley may affect the South Okanagan as water flows south through the mainstream lakes,” the town said in a joint news release with the Regional District of Okanagan-Similkameen (RDOS) issued Thursday.
“The prediction of thunderstorms and rain by Environment Canada starting Thursday, May 11 could add additional volumes of water moving through the lakes system to Osoyoos Lake,” the news release said.
Sand and sandbags have been available at the Public Works yard in the industrial park and sand will be placed across Highway 3 from the Dairy Queen.
The town said it is currently awaiting a new shipment of sandbags and sand from the province and the locations will be posted on the town’s website at www.osoyoos.ca.
“We are being proactive, in anticipation of the heavy rain in the next few days and the higher temperatures bringing down the snowmelt into the Similkameen River,” said the joint statement signed by Dale Kronebusch, RDOS emergency operations supervisor, and Janette Van Vianen, Town of Osoyoos emergency program co-ordinator.
“The Town of Osoyoos will take precautionary measures by sandbagging its critical infrastructure along the lakeshore in order to protect the Town’s sewer lift stations in the event of possible flooding,” the news release said. “Residents and business owners along the shores of Osoyoos Lake who have had high water levels and needed to sandbag in previous years should know where to access sandbags by calling either the Town of Osoyoos or the RDOS.”
Osoyoos Lake surpassed 913 feet above sea level around 7:30 a.m. Thursday and is continuing to rise.
But Okanagan Lake has been most affected, with the lake rising about three centimetres a day, according to the B.C. River Forecast Centre.
“This may have implications on lake levels downstream, including Skaha, Vaseux, Oliver river system and Osoyoos Lake,” the RDOS said in an information release on Wednesday.
The water level on Okanagan Lake is partially regulated by a dam at Penticton, which is operated by the province.
Shaun Reimer, who oversees the operation of the dam for the Ministry of Forests, Lands and Natural Resource Operations, says it is a balancing act to try to lower the level of Okanagan Lake while trying to avoid flooding downriver.
Meanwhile, the volume of the Similkameen River as measured at Nighthawk, WA has been increasing since Wednesday morning, according to the U.S. Geological Survey.
At 6:15 a.m. Wednesday, the Similkameen’s discharge was 9,920 cubic feet per second, but by 1:30 p.m. Thursday it had increased to 11,300 cubic feet per second.
This is still below the peak of 15,200 cubic feet per second reached on the weekend.
The volume of water in the Similkameen River is a major factor affecting the level of Osoyoos Lake, because when water backs up from the confluence of the Similkameen and Okanogan Rivers at Oroville, water can’t drain effectively from the lake at the Zosel Dam.
Meanwhile, a special weather statement and severe thunderstorm watch remain in effect throughout the Okanagan, according to Environment Canada as of Thursday afternoon. Those alerts were issued Thursday morning.
Environment Canada warns of the potential for severe thunderstorms due to a coastal cold front sweeping eastward across the mountains into the southwest interior in the afternoon.
By Friday morning, 15 to 25 millimetres of rain is likely to fall over many reaches, with potential for higher amounts in regions hit by severe thunderstorms.
More precipitation is expected over the weekend.
RICHARD McGUIRE
Osoyoos Times
