Columbia River/Lake Wallula 

I live here where you were fishing. The big bass are deep in the summer. There is a good population of freshwater shrimp (Siberian prawns) that they gorge on, in addition to crawdads and most of all salmon & steelhead smolt. There are also several resident baitfish. Good luck if you ever return. The Snake River is also full of bass, hardly ever fished. By the way, there is no limit on bass in Lake Wallula or the Snake River.