The Tieton River's waves are expected to pick up early September. The biggest weekend flow is set on the second and third weekend, September 8 to 9 and 15 to 16, provided there are no significant changes on the irrigation demands and of course the weather.
That is when the Bureau of Reclamation is preparing for the yearly "flip-flop" operation. The process includes the reduction of flow in the upper Yakima River in order to boost salmon spawning, while replacing that water supply for irrigators by increasing the flow on Tieton with the help of the Rimrock Reservoir.
However, commercial rafting outfitters will not resume operation until next week though several rafting enthusiasts have already booked this weekend when the water flow is still at 1,000 cubic feet per second.