Osoyoos Lake levels are rising

High inflows into Okanagan Lake are affecting water flows south of the border

  • Apr. 1, 2018 5:30 p.m.
Osoyoos Lake levels are rising

A graph from the Department of Ecology in Washington State shows snowpack levels compared to previous years.

Officials in Washington State are concerned over rising water levels in Osoyoos Lake, which straddles the Canada-U.S. border.

A release issued Friday notes that water levels in Osoyoos Lake are rising as Canadian water managers in Penticton continue to release water from Lake Okanagan to prepare for expected high inflows into the lake from melting snows later this year.

Osoyoos Lake is the southernmost body of the Okanagan Valley water system, which includes Skaha and Okanagan Lakes. Outflow of Osoyoos Lake is regulated at Zosel Dam, near Oroville, Wa., and is managed by the Washington Department of Ecology.

Operational activities on the Okanagan river system in B.C. influence Osoyoos water levels, and making room for snow runoff in the upper watershed puts pressure on Osoyoos Lake.

“Once the Zosel Dam gates are wide open, as they are right now, Lake Osoyoos must seek its own level when runoff is high throughout the system,” said Al Josephy, with the Department of Ecology’s water resources program.

With greater than 100 per cent of average snow levels reported in all watersheds in the region, the Washington Department of Ecology intends to manage to the usual summer target level at Osoyoos Lake of between 911.5 and 912 feet from May 1 to Sept. 15.

“We’ll continue to coordinate with our Canadian partners in managing our end of the system as the spring weather progresses,” Josephy said. “This can cause inconvenience and occasional flooding to property owners along the lake and down the river itself.”

Lake levels are mandated by the International Joint Commission (IJC), a board made up of representatives from the U.S. and Canada. Osoyoos Lake is a source of irrigation water and summer recreation in both the U.S. and Canada.