Trout fishing on the Walla Walla, and its tributaries, is open through until Oct. 31. Fishing on the Walla Walla has been good in the past week or more with the flows being consistent. Anglers have found success in the smaller pools using both dry flies, nymph flies and small spoons. It is illegal to target bull trout in this stream and anglers so immediately release a bull trout if caught.