Yeah, I suppose they are too big to be a tadpole in metamorphosis. After looking online for pictures resembling what I've been seeing, the only thing that's close is the rough skinned newt. Which would most likely explain why I see them in such abundance, as I believe they are poisonous to predators, so I don't know that a smallmouth could eat them. I see them suspended in the really slow water. Only other thing I can think is a mud puppy/water dog, but I can't find any pictures with those colors.
Thinking back, the frogs I have seen on the Umpqua are pretty small and yellowish in color. I fish pretty close to Umpqua, too. Usually put in at Mack Brown, I believe.
"There's never enough time to do all the nothing you want." - Calvin