Fall River is crowded but man there are a lot of happy fish in there now. Summer conditions. When the hatches are on we’ve been getting fish up on PMD’s, purple comparaduns, ants, beetles, olive caddis, yellow sally and midges. Attractors have some game and don’t be afraid to twitch and skate flies like a hippie stomper or PMX. 
Jig streamers and balanced leeches are really effective and can be fished dead drifted or stripped, and you can dead drift them on the same leader you sightline your perdigons, eggs and mops.