As Charlie mentioned below, we're still a couple of weeks away from the prime Spring hatches on the Yakima, but based on a trip over there on Sunday all signs are pointing toward the fishing heating up big time. In 4-5 hours of fishing and exploring water near the confluence with the Cle Elum, these two fish came to hand, with a 3rd of probable equal size making a nice charge at the fly twice. All 3 fish were in water you'd expect to see fish in this time of year--deeper, slow-moving troughs--and all 3 were enticed by big streamers. We were fishing with river flows at Umtanum posted at 1200, and only encountered a couple of river crossings that would be considered border-line aggressive. There's also snow still surrounding the river, so be prepared for hiking through that potentially. All in all, if you know where to access the Upper Yakima, and the flows aren't spiking (like they're doing as I type this), the trout seem to be gearing up for Spring.