We are seeing some low water levels here in the Bitterroot but there is still access to some fishy spots with deep holes. The fishing is substantially better in the early mornings, and you'll have better opportunities for a dry eat at that time. Consider using a spinner or PMD and then as the afternoon heat starts rolling in switch to your favorite hopper pattern with a dropper on it. Cast close to the bank and don't be afraid to make a splash, fish look for those hard-hitting hoppers coming from the grass's edge. Perdigons and Duracell's have been working best for nymphing, if the fish aren't rising at all consider doing a double nymph rig under an indicator to get down in the holes of the river.
The lower river is currently at 220 CFS, upper river is 350 CFS, and the West Fork is 185 CFS. The river is fairly narrow so if you're floating make sure you scout out your float prior to launching.