Osoyoos Lake level returned to normal following early summer snowmelt

Levels set by International Joint Committee maintained through Zosel Dam regulation

Okanogan-Similkamenne River Basin

OROVILLE/OSOYOOS – After early summer snowmelt led to higher levels, Osoyoos Lake was returned to levels set by the International Joint Commission (IJC) through regulation of Zosel Dam near Oroville.

On July 27, 2022 Osoyoos Lake level declined below an elevation of 912.0 feet (277.97 meters), the upper limit of the rule curve defined by Condition 7 of the IJC Order of Approval for Osoyoos Lake (fig. 1, blue line). The level of Osoyoos Lake exceeded the rule curve from June 8 to July 27 in response to increased inflow from snowmelt and decreased outflow due to elevated stage of the Similkameen River during the spring freshet. Osoyoos Lake crested at an elevation of 912.99 feet (278.28 meters) on June 22.

The operators of Zosel Dam remained in compliance with the IJC Orders during the spring freshet by fully opening the gates at Zosel Dam such that Osoyoos Lake levels were only controlled by inflows and outflows, which were limited by the higher stage of the Similkameen River. Regulation of Osoyoos Lake by Zosel Dam will resume now that Osoyoos Lake levels have returned to within the rule curve.

Please monitor this site for further hydrologic condition updates as the summer progresses. Real-time Osoyoos Lake levels are available on the IOLBC’s website: www.ijc.org/en/olbc.