The mountain native brook trout streams are low and clear. The brook trout are very wary so fish the streams where you can use the gradient areas to hide your approach and if need be--go to your hands and knees. The water temperature has been in the high 60's so the trout will not be feeding as actively as they did in the spring. Try to be on the stream in the early morning hours and for better water levels, hike in from the bottom boundaries and walk about a half hour before starting to fish. The Hughes and Rose River usually hold more water in the summer months. For access on these streams, see my book Trout Fishing in the Shenandoah National Park.
I have been doing well with the Mr. Rapidan Midge in a size 18 and the Murray's Flying Beetle size 16. If you are on the stream in the evenings you will probably see many natural moths. Fish the Murray's Moth size 16 upstream with a slow twitching action. Fish all of these on a 6x Murray's Classic 7 1/2ft Leader. Sometimes you might even have to go to a 7X leader. At this time of year I am not saying you cannot catch a trout--just that it is much tougher than in the spring.