By this time of year the trout in most popular streams have seen the standard artificial flies over and over again. So you should consider showing them flies with a different look. The Murray's Housefly with its floating grizzly wings and opaque body shows the trout a realistic insect silhouette which they seldom see. Experiment with different style and colors to show the trout something different.
These streams are getting very low and the fishing is tough. Choose a stream that has a better water volume, higher gradient areas, and come in from the lower boundary access of the Shenandoah National Park. Sneak, sneak, sneak and hide your approach and do the best you can in these tough conditions.
If you need help on access, stop by the fly shop or see my book Trout Fishing in the Shenandoah National Park.