Fall releases on the Tieton River began this week and should be good for this coming weekend. Every year around Labor Day the Bureau of Reclamation begins their annual drawdown of the Tieton River's Rimrock Reservoir. Up until this date, reservoirs on the Yakima River provided the majority of the flow for irrigation needs in the Lower Yakima Valley. With these reservoirs almost empty (teacup diagram), the Bureau of Reclamation initiates the annual flip-flop, which consists of reducing flows on the Yakima and increasing flows on the Tieton to serve irrigation needs at the end of the season.
Flows from reservoirs on the Yakima River are being reduced and release from the Tieton is being increased to approximately 1100 to 1500 cfs by Labor Day. Peak flows should occur September 10th or possibly a few days later. All flows are tentative and vary depending on irrigation demand and the weather. Check the Tieton gauge before you head out if you don't want to be left high and dry (if this link is not working the Army Corps provides an alternate gauge link)
Whitewater paddlers may be interested in knowing that Congress recently authorized a study to examine storage needs for the Yakima project (additional information) but there are currently no plans or authorization for additional construction or changes in operation of the Yakima project. At this point it's just a study and there is no relationship between this study and ongoing operations (it might not be a bad idea to get on the mailing list though if you want to stay in the loop).
Recreational boaters and commercial outfitters benefit from the dependable fall releases that come at a time when other regional rivers are at a seasonal low. Flows are typically held above 1000 cfs for a couple weeks depending on storage in Rimrock Reservoir. Based on this year's irrigation needs and current reservoir level, the river operator has confirmed we can likely expect flows to be at least 1000 cfs for at least the next couple of weeks. At this level the river is class III+ and considering the local options for this time of year there is at least one decent park-and-play spot. Because flows on this river are tightly regulated, vegetation has grown up along the banks of the river making for a shoreline that is very brushy. Rescues can be a pain.
For additional information and daily updates call the flow information line at 509-575-5854 which will provide information on current project operation. The same information can also be found on the Yakima Project system status page which is updated each morning. To speak to a person there is additional contact information for the river operator at the end of the phone recording.
In other news on the Tieton, a new hydro project now operates at the existing dam. As part of the
license to operate this project funds will be available for recreation needs along the river