No, that's not a muskrat, or a beaver...
I found a new use for my fishing partner, Bert the Boykin. On nice warm days, like yesterday (94) I just turn him loose at the head of a riffle and he swims around a bit or just lays down in the water. The effect is deadly. The Boykin scent attracts fish from miles around and the results are devastating. In a few hours I caught 5 smallmouth topped by a 17" fish, plus three channel cats. One channel cat was around 10 pounds and we had a dandy fight out of him.
The riffle shown above is usually covered by about 6" of water. The level is controlled by a power dam about 25 miles upstream, and I never know what I'm going to find when I head to the Snake River. Also that upper view is only half the river. The land on the right is an island. For the benefit of you fly fishermen, I've caught lots of smallmouth in the river on flies - my most productive has been a yellow maribou Muddler Minnow - but I usually catch bigger fish on topwater lures or soft plastic baits. But I'm sure you can see the potential of wading that riffle. 75 year old geezers get a little leary of wading a river like the Snake.