Acting on a suggestion from the Orvis shop in Bethesda, I fished at the Howard Chapel Road crossing. Yesterday, the guy at the fly fishing store pointed out that today would the last opportunity for a while since rain is forecasted for the next four days.
I felt some insects on my neck a couple of times which looked like stoneflies, but there were no visible rises so I fished streamers downstream from the bridge. A Patuxent Special didn't produce, so I switched to an orange Crystal Bugger and walked further downstream to where there were no footprints. Caught a nice rainbow about a foot long and then a small chub. Noticed some piles of mud which indicate the presence of beavers, and soon saw confirming evidence on some trees.
Water level was 2.8 at Unity, and air temperature was in the upper 50's.