I've been targeting smallmouth on my local stream heavily for 3 years now. I started out using small poppers, small spinnerbaits and buzzbaits, and other small lures. Lately, I've changed my strategy.
In the last 2 weeks I've caught 3 fish over 16" along w/ many others. One measured 20". I've been throwing a 3/8 oz. war eagle buzzbait, black with gold blades. The smallies are loving it and it is weeding out the dinks. Throw it over deeper water, in the current, and by structure.
As far as a popper goes, I use a #7 skitter pop and make short quick pops as fast as I can. Sometimes I pause once or twice during the retrieve and other times I just keep popping it all the way in. They inhale it even when its going fast.
By the look of your pic, the stream I'm fishing is about the same size, no bigger.