Fly fishing the Boulder River is not something most visitors to the Livingston/Bozeman/Gardiner area think to try. In fact, not many anglers even know the Boulder exists, since it’s east of Livingston, rather than west and south like the rest of the region’s float rivers. The best way visitors can experience fly fishing the Boulder River is to take a float. Guided float trips require the use of whitewater rafts, due to the “bouncy” nature of the river (it’s very steep and fast), its many namesake rocks as well as a few other obstructions like low-head dams and log jams, and the terrible accesses, which in a couple cases require sliding the boat down (or up) steep, rocky slopes into (or out of) the river.
Fish populations in the lower, floatable portion of the Boulder include rainbow trout averaging 10 to 16 inches, browns averaging 12 to 18 inches but reaching trophy size, and some monstrously large whitefish.Fishing the Boulder when it’s between 1800cfs and 3000cfs means nymphing the perfect water: deep, slow, green runs. Basically the water that looks the best is the best. This is a mark of how little pressure this river has received so far this season. In two days of floating last week, we saw a total of three other boats, two guide rafts and one solo floater in a small boat. The pressure does increase a lot as the water drops, but it’s still a far cry from the popular Yellowstone or Madison.
From the moving raft, this is fast-paced nymph fishing, with casts flinging left and right, all while wearing a life jacket in case of a “Big Oops” on this rough river. When possible, it makes sense to pull the raft over into the few broad pools, then get out and wade fish the back sides of these riffle corners. While the fish disperse when the river drops from 1800 to 600cfs (after which it becomes far too low to float), for now they are concentrated in these obvious good areas.
On June 26, Kody Marr and I floated the lower Boulder, from 8-Mile Bridge to the town of Big Timber just above the Yellowstone. Flows were around 2200cfs. Big, but well under the 3000cfs cutoff I consider safe to float. Visibility was excellent at six or more feet. Unlike the Yellowstone, the Boulder basically stays clear even during runoff. It’s high flows that make it unfishable, seldom the color.
It took us a while to get the fishing dialed, but after we did, it was game on. The fish wanted Golden Stonefly nymphs and small attractors like Princes about equally at first, but as we got down towards Big Timber, a caddis hatch began. There were a few risers here and there, but the dry fly fishing here gets a lot better when the river drops some more, so we stuck with nymphs. The Prince was apparently close enough to the caddis pupae, because the trout were crushing it.
The best fish we landed is pictured above. It ate a Bead, Hare, and Copper nymph. We lost some that were certainly bigger, including a brown that might have been over 20 inches that Kody lost just before the takeout.
On the 27th, I guided a single angler on the Boulder, after the Yellowstone came up enough to make it a poor choice as we had planned. The Boulder rose too, to 2600cfs or thereabouts. While this made the fish shift almost exclusively to eating large stonefly/attractor nymphs (Stone Bombs and Mega Princes, both in #6), otherwise the fishing was great. Though she could not get out to wade the good corners due to a lack of wading shoes and poor balance, my angler still landed around 15 trout, including three browns over 15 inches, and lost easily twice that number that either shook the hook after a couple head-shakes due to a poor hookset or simply got downstream of the boat and pulled lose. A couple of these fish looked to beat the fish pictured below, the best she landed.
While it came up a bunch in the following days, as of this writing the Boulder is on the drop again and back under 3000cfs. I expect to guide on it at least three days a week from now through July, continuing to do so until it drops out of floatable shape sometime in the first week of August. I don’t have many open days in this period, but I do have a few. The Boulder makes a great alternative or add-on to the Yellowstone, particularly for experienced anglers eager for a change of pace. Interested?