I've never fished the Yakima River but there are spots along I-82 where you can park and walk along the river to fish for trout. Throw some jigs for them though, one of the old timers told me he catches some nice sized trout throwing crappie jigs in the river, or if you flyfish you could do that too in some spots. There are a ton of ponds from Yakima to around Exit 52 to fish from. Myron Pond in Yakima holds some nice sized trout but it's selective gear only. People have been catching trout from Rotary Lake too, I haven't been there in two or three weeks though, I primarily go there for crappie. Then there's the I-82 ponds, I mostly fish ponds 4,5, and 7 for panfish so I'm not really sure about the others and how they do for trout on them.
