I'm not sure about the gravel bar but it used to be directly below the dam on the far side.
Nymph fishing is an attempt at futility down on the flats though in the canyon where there is far less food and the river is more like most western rivers it's done often.
Did you notice how hundreds of swallows come from nowhere seconds before a blanket hatch starts? Often have wondered how they know as the swallows are more than a hunded yards away from the river and then they are skiming the water exactly as the first duns wings begin to dry. The bats in the evening caddis hatch are a sight to see too. Hope that there are still many left as they are a great indicator of the health of the watershed.
The A-bar used to be bad burgers, pool games and good clean healthy fist fights, boy was that a nice way to relax after a long day of intense fishing.