Department of Ecology News Release - July 31, 2015

Drought conditions prompt changes in Lake Osoyoos levels
More water will be stored now to support Okanogan River flows in the fall

OROVILLE – Continuing drought conditions affecting water supplies in the Okanogan River Basin has prompted changes in how Osoyoos Lake will be managed for the rest of the summer.

Dam operators will store more water in the lake now in order to support river flows in the fall.

The International Joint Commission (IJC) that governs management of the lake is allowing the Washington Department of Ecology to operate Zosel Dam with more flexibility in response to worsening water supplies in the region that straddles Canada and the United States.

From now until Nov. 1, 2015, lake levels will comply with the drought rule curve for the cross-border lake, although drought has not been officially declared in Canada. A statewide drought was declared in Washington on May 15.

“The temporary variance approved by the IJC allows water managers more flexibility in responding to the worsening water supply in Washington,” said Al Josephy, Ecology’s operations manager at Zosel Dam. “This will allow operators to store an extra half-foot of water that can be released at the end of the summer if needed to keep the river hydrated for a longer period into the fall.”

The change will allow lake levels to vary in a greater range from 910.5 to 912.5 feet. Normal operations maintain summer levels from 911 to 912 feet until Sept. 15, gradually decreasing to winter management levels by Nov. 1.

Osoyoos Lake serves as a source of water for irrigation and summer recreation in the U.S. and Canada. Lake levels are mandated by the international joint board and overseen by the International Osoyoos Lake Board of Control, both of which are made up of representatives from the U.S. and Canada.

For more information about Osoyoos Lake and the operation of Zosel Dam, contact Al Josephy at Ecology at 360-407-6456.


Joye Redfield-Wilder, communications,, 509-575-2610; @ecyCentral