IJC issues order for future management of Osoyoos Lake levels

The IJC announced that it has issued an Order of Approval renewing the State of Washington’s authority to operate Zosel Dam


The International Joint Commission (IJC) announced on Thursday, January 31 that it has issued an Order of Approval renewing the State of Washington’s authority to operate Zosel Dam and making minor modifications in how water levels on Osoyoos Lake will be managed. The dam, located in Oroville, Washington is subject to international jurisdiction because it regulates the outflow from Osoyoos Lake, and backs water across the border into British Columbia.

“Thanks to the active participation in the process by watershed residents and input from the State and Province, the IJC was able to thoroughly vet the issues affecting both countries before revising this Order,” said Commissioner Lyall Knott of the IJC.

“As we move forward, we will continue to engage stakeholders in the watershed, and keep them advised of the reservoir operations and water levels. Cooperation is an ongoing process,” commented IJC Commissioner Rich Moy.

The current Orders for Zosel Dam were scheduled to expire in February and April 2013. The renewal process began in 2000 with the scoping of issues related to water levels, future water supplies and water quality in order to develop a plan of study. A number of these issues had been raised at the annual public meetings of the International Osoyoos Lake Board of Control (the Board), which was appointed by the IJC to oversee implementation of its Orders. The IJC launched eight studies in 2006 and these were completed in 2011. Stakeholders also held in-depth discussions of watershed issues at the Osoyoos Lake Water Science Forums held in September 2007 and September 2011.

In a June 2012 report to the IJC, the Board concluded that the current Orders have adequately facilitated control of water levels in Osoyoos Lake, to the extent possible, primarily for the benefit of agriculture, tourism, municipal interests, and fisheries protection. The board recommended only minor modifications to the rule curve that sets Osoyoos Lake upper and lower target water levels for different times of the year. The previous rule curve had specified that the lake be maintained within a half-foot range (911.0 to 911.5 feet) from April through October during normal conditions, but be allowed to rise to 913.0 feet during drought years. The board recommended that the maximum elevation be reduced to 912.5 feet with the flexibility to regulate within a two-foot range every year, thereby eliminating the need for drought declarations. The rule curve recommended in the board’s June 2012 report also provides for a more gradual transition in water levels during the spring and fall.