The Boulder River will probably hover at its lowest flows of the year for the next few weeks until irrigators stop pulling water. Despite the low flows, it is fishing well but you need to cover a lot of ground....which always easier said that done on the Boulder River because the walk-wade fishing is tough with all the...you guessed it...boulders. Quality boots and relatively good physical condition is important if you are going to fish the Boulder River at these flows. Getting around is much easier than at higher flows, but the average size of boulders in the Boulder River makes it difficult to walk and wade. A wading staff is a good idea when fishing the Boulder.
If you do fish it, single hoppers and ants and beetles should work quite well. If the fish are not looking up try a Pat's Rubber Legs, 20 Incher, or Mega Prince in combination with a Duracell, Prince, Blowtorch, or Lil' Spanker are all great options to start with. Dry fly fishing has been good with surface activity increasing in by mid morning. Chubby Chernobyl, Stimulators, and attractor dries are all a great option to get some trout looking up.
Water temps are still good since it drains some of the highest mountains in the state. However, because of the clear and cold water, many of the trout on the Boulder River right now are getting a little spooky. This isn’t a big fish river but it is fun river to cast attractor dry flies or fish the many runs of pocket water. There are a lot of trout in skinny water in tail outs but when they go on the feed they also move into the shallow riffles.
For good anglers and strong waders, the Boulder is good alternate option to some of the more well known rivers in the southwest Montana. The Boulder River is low and gin clear right now, with flows holding steady around 85 CFS, though they will continue slowly dropping. This is a near-impossible level for floating anything larger than a one person pontoon or kayak.
Best Flies for the Boulder
20 incher #6-10
Duracell #14-18
Prince #12-16
Blowtorch #14-18
Lil' Spanker #12-18
Chubby Chernobyl (Purple, Yellow, Tan) #6-14
Stimulator #8-16
Foam Run Caddis #12-16
Baby Gonga (Olive) #4-8
Mini Dungeon (Olive, Natural, Tan) #4-8
The Month Ahead:
The Boulder should fish well into the fall with nice cold water temps keeping trout happy. The clear water and low conditions produce spooky trout some making the right cast is always important.
Long Term Fishing Forecast:
The Boulder River is a nice option in September as hoppers and some early Blue Winged Olives can provide some exciting dry fly fishing. In October some browns move up from the Yellowstone to add some big fish to the mix.