Canada releases pulse flows to the Okanagan River

The state Department of Ecology regulates lake levels at Zosel Dam in Oroville. Lake levels can fluctuate into early July depending on snowpack. Ecology seeks to maintain the water level between 911.5 and 912 feet from May 1 to Sept. 15, but occasionally there’s a chance for flooding when snowmelt and runoff are high. Gary DeVon/staff photo

The state Department of Ecology regulates lake levels at Zosel Dam in Oroville. Lake levels can fluctuate into early July depending on snowpack. Ecology seeks to maintain the water level between 911.5 and 912 feet from May 1 to Sept. 15, but occasionally there’s a chance for flooding when snowmelt and runoff are high. Gary DeVon/file photo

Increase in flows to help salmon

Submitted by Joye Redfield-Wilder

Washington State DOE – Central Regional Office

OROVILLE – Dam operators in Penticton, BC are raising flows in the Okanagan River to assist migrating salmon on their trip down the Columbia River system to the ocean.

Beginning Aug. 29 and continuing for approximately eight days, Canadian authorities will be ramping up flows from Lake Okanagan from current late summer levels to about 1,250 cubic feet per second.

According to the Washington Department of Ecology, which manages Osoyoos Lake levels at Zosel Dam, recent flows in the Okanogan River at Oroville have been typically low for late summer, at about 250 cubic feet per second. These flows will rise over the next several days to over 1,000 cubic feet per second as more water is released from Lake Okanagan. This “pulse” is planned to last for just over a week, after which the river will subside to its usual low conditions for late summer.

During this pulse, residents at Osoyoos Lake can expect to see the lake rise about three to four inches as dam operators work to “feather” increases in flows in the river below Oroville so as to not put too much water into the river suddenly. You can watch this work develop by watching the river gauge at Oroville at http://waterdata.usgs.gov/.

Osoyoos Lake levels are mandated by the International Joint Commission, a board made up of representatives from the United States and Canada. Ecology’s target is to maintain Osoyoos Lake at a level of between 911.5 and 911.8 feet until Sept. 15. After that, the lake will slowly be brought down to winter operations by November.

More information on the International Osoyoos Lake Board of Control can be found at http://ijc.org/boards/iolbc/.

To track the progress of lake levels in “real-time,” as well as find additional information, go to the U.S. Geological Survey web page for Osoyoos Lake.