The river’s looking great and fishing amazing as well! There’s lots of golden stones, pmd’s, and caddis throughout the entirety of the Yakima. There’s also a lot of larger fish willing to eat a streamer right now, and it’s an awesome time to fish trout spey.
For flies, bring a variety of Chubby Chernobyl’s in a wide range of sizes (anywhere from a 14 to an 8), and smaller nymphs that you could fish as a dropper. Hare’s ears, pheasant tails, and pmd nymphs have been working great. For streamers, lil kim’s, sparkle minnows, and sculpins have been the most effective. Make sure you fish them with a sink tip to get them down to the fish.
The smaller tributaries to Yak have also been fishing fairly consistently. The Lower Teanaway has some rainbows in it that are up from the Yakima, but the upper reaches are a ton of fun with small cutthroat eating any dry fly that they can fit in their mouth. It’s been the same on the Upper Cle Elum, just a bunch of small fish eating dries. It’s best to use the smallest rod you have to make it a bit more fun.
Just a reminder, if you’ll be floating or launching at the state boat launch be sure to use the right channel just below the launch. There’s a massive log jam on the main stem of the river that’s impossible to pass.