The Zosel Dam in Oroville, WA helps to maintain the level of Osoyoos Lake. It also forms a barrier for sockeye salmon migrating up the Okanogan River in Washington to Osoyoos Lake. (Richard McGuire photo)
Dam operators at Penticton are raising flows in the Okanagan River to assist sockeye salmon on their migration.
Beginning Aug. 29 and continuing for approximately eight days, Canadian authorities will be ramping up flows from Okanagan Lake from current late summer levels to about 1,250 cubic feet per second, the Washington State Department of Ecology said in a news release.
Ecology operates the Zosel Dam on the Okanogan River at Oroville, which regulates the level of Osoyoos Lake and the flow of water downstream.
Recent flows in the Okanogan River at Oroville have been typically low for late summer at about 250 cubic feet per second.
These flows are currently rising and will reach more than 1,000 cubic feet per second as more water is released from Okanagan Lake.
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 on 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.
Osoyoos Lake levels are mandated by the International Joint Commission, a board made up of representatives of the United States and Canada.
Ecology’s target is to maintain Osoyoos Lake at a level between 911.5 and 911.8 feet until Sept. 15.
After that, the lake will slowly be brought down to winter operations by November.
As of 4 p.m. Tuesday, the level of Osoyoos Lake as recorded at Zosel Dam was 911.52 feet above sea level.
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