Past Activities


Temporary Variance approved for summer 2015 Osoyoos Lake levels.

On July 28, 2015, the International Joint Commission (IJC) approved a temporary variance from the standard, non-drought rule curve for Osoyoos Lake (specified in Condition 7 of the Order) that had been in effect up to this date. As a result, the Washington State Department of Ecology (Ecology) is allowed to operate Zosel Dam according to the drought-condition rule curve specified in Condition 8 of the Order until November 1, 2015, even though the drought criteria specified in Condition 8 have not all been met. The IJC approved the variance under Condition 10 in recognition of the need for more flexibility in the operation of Zosel Dam during this year’s extreme hydrologic conditions that have led both Washington State and British Columbia to declare drought emergencies.

Washington State Department of Ecology's press release about the operational implications of this variance for Zosel Dam (and water levels on Osoyoos Lake) can be accessed at:


Plan of Study reports 

The IOLBC contracted various technical and scientific studies to provide necessary information to the IJC in the period leading up to renewal of the IJC Order for Osoyoos Lake in 2013.  These studies helped to inform changes brought about in the form of the IJC's Supplementary Order of Approval for Osoyoos Lake in January, 2013.  The studies are identified as follows (click link to see the reports):

Plan of Study Report (overall summary)