Montana’s Beaverhead River

Cold, clear water releases from Clark Canyon Reservoir, a healthy streambed that bolsters terrific aquatic insect hatches, and strict angling regulations are the three biggest reasons Beaverhead trout are able to pack on the pounds. But with so much going for them, fooling fish becomes significantly more difficult. They see a lot of food, a lot of flies, and just like the fish on many other tailwaters, these frout have perfected “the snub”—the moment when a particularly cruel fish approaches like it’s going to strike, nearly touches the fly, and then turns away at the last moment). Dwelling in such tight quarters and dealing with the constant bombardment of flies nearly every day of the year, they’ve come to see a thing or two and the old-reliable patterns you dig out on the state’s freestone waters don’t fool “Beav” fish like they used to.

Since 2000, summers have been brutal in southwestern Montana. Fires, drought, and record high temperatures have forced full and partial closures on many of the state’s waterways. The Beaverhead’s blessing is that it flows through an arid landscape and there’s little danger of forest wildfires flanking its banks. What’s more, the bottom-flow releases from the reservoir maintain a comfortable water temperature for trout on days when freestone water temperatures approach 70 degrees. This makes the first 10 miles or so of the Beaverhead a solid alternative if you’re forced to change travel plans because Mother Nature deals an unlucky hand elsewhere. From Dillon downstream, however, diversion dams and irrigation demands take their toll and the number of fish per mile declines substantially.

When flows are high (800 to 1,200 cfs) float fishing is the best method for tackling this river, though use caution in the deceivingly swift water. Powerful currents, willow-choked banks, and a slippery stream bottom make it tough to get a decent presentation otherwise. Boats are also a great tool for reaching side channels and backwater sloughs—favorite haunts for some of the river’s largest trout and the ultimate challenge for anyone looking to test their spot-and-stalk fishing skills.

Unfortunately, there is no easy way to float the Beaverhead. I often joke there isn’t a straight line on this river, and when you combine a series of twists and turns, high flows, and an armada of drift boats and rafts, it pays to have a skilled set of hands on the sticks.

Outside of the public-access points, private land boundaries and natural structure such as bankside willows make it tough for wading anglers to reach some areas of the river. So in my opinion, if you want to get the most out of a boat on the river, use it as a shuttle from hole to hole. In doing so, remember that sometimes the best fishing isn’t along the banks or near structure; it’s in the middle of the river, and the only way to reach it is to shore the boat, jump out, and run a few casts in slicks you would normally drift over.

 Unfortunately, crowds and fly fishing dont mix, so courtesy and polite boat handling are a must. In areas where boats are anchored and fishing a particular run, it’s sometimes impossible to float anywhere but over the pool they’re targeting but do it as quickly and quietly as possible. Don’t slow the boat or cast over a fish someone else is pursuing.

 Coincidentally, as the water level drops, the amount of underwater vegetation often increases, providing fish with ample cover. They can hang out in the middle of the river inside the eddy of the largest chunks of swaying grass, or wedge themselves between a moss bed and undercut bank.

When water levels drop to 300 cfs or lower (usually duri.ng the late summer when the growing season winds down) the fish become concentrated, and you will see many more fish than you will catch. It’s also the best time to wade-fish since shallow areas make it tough to float. The river ‘s large browns and rainbows can hold in only a few inches of water along the banks, near tributaries, or next to undercut banks. They’re accustomed to high angling traffic, and large fish will feed without abandon a few feet from you. One day I spotted an 18-inch rainbow in ankle-deep water feasting on spent Tricos almost directly behind my friend. Unbeknownst to him, I made a slack-tine cast

downstream, fed line into the drift, and fooled the fish into rising. Unfortunately, the hook pulled free, but the moment gave us a good laugh on an otherwise frustrating morning.

Where and When

The most popular area is below Clark Canyon Dam to Grasshopper access. In the 1990s, this area was subject to so much angling pressure the state enacted special regulations that dictate when outfitters and nonresident anglers can fish different sections, depending on the day of the week. Though this helped alleviate some crowding issues, the Beaverhead’s width still makes it feel like one of the most crowded waters I’ve ever fished.

The campground and access just below Clark Canyon Dam on the western shoreline is the uppermost access. The boat ramp is unimproved, but since it’s the highest point anyone can launch on the river, it’s popular. The whirling pools on the left and right of the dam’s outflow have plenty of fish to target, though catching them is another issue altogether.

It’s a short float from the dam to Buffalo Bridge (Low Bridge). This public access is nearly invisible from the road, and a gravel pathway along the southern edge of Armstead Campground makes it appear as a private launch. From here, the river follows a frontage road and eventually intersects the High Bridge access—so named because of the elevated highway bridge (1-15) that looms overhead. The unimproved boat ramp and small parking area make this access a popular one for short floats. IVs also a good spot for wading anglers to jump in and work downstream when water levels are 300 cfs or lower.

There are two Henneberry access points on the Beaverhead River downstream from High Bridge. The southern access is for foot traffic only, the northern (nearly two miles downstream) sits next to a small bridge and affords a place to load or unload a boat. From the Henneberry boat ramp floating anglers can cover a healthy portion of the Beaverhead and take out at Grasshopper. If you put in late, however, look to Pipe Organ Bridge just a couple of miles downstream. One of my favorite summertime schemes is to float the upper river early, relax through the heat of the day, and float again from Henneberry to Pipe Organ during the waning evening hours. Not only do rarely see anyone else fishing, but the fish are seemingly more willing to rise when evening caddis are popping.

The river twists, turns, and forks a few times below Pipe Organ Bridge. This makes for some tight quarters if you’re in a boat, but keep an eye out for good wade-fishing areas and use the boat more as a shuttle, at least until channels rejoin on the downstream side of islands and it’s easier to maneuver.

The river straightens and the flow picks up in the last mile just upstream of Grasshopper. I almost always switch to streamers or large terrestrial patterns and pound the banks from a boat since there’s nowhere to run but the middle of the river. It’s one last opportunity to pick up a fish or two before reaching the Grasshopper boat ramp. During runoff, Grasshopper Creek pushes a decent amount of muddy water into the system, so if you’re looking to begin your float here, check the conditions first so you’re sure to have clear water downstream.

From Grasshopper to Dillon the fish are less concentrated but also less finicky. Given that, it doesn’t receive as much pressure from anglers. Before you decide to drift it, remember Barretts diversion dam cuts the flow substantially (and requires a portage) greatly affecting its navigability, and what’s left flows mainly through private land with limited access.

Fishing prospects decline from Dillon to the junction of the Ruby River outside Twin Bridges. In the summer, irrigation demands, water temperature, and limited access make for tough fishing. When water temperatures drop in the early fall, conditions improve, but plan your put-ins and take-outs carefully to avoid unnecessarily long days on the water. In some cases, drought or other issues may force trout from the Big Hole or Jefferson up into the lower Beaverhead.

Hatches and Flies

By and large, nymphing is the most effective technique on the Beaverhead, especially in the upper river between the dam and Henneberrv. Dry flies have their place, but I keep them stashed unless I’m targeting a specific rising fish. it doesn’t matter if you’re casting from the bank or a boat, it’s hard to beat a two-fly nymph rig and indicator—though some go without “a bobber” under the theory that Beaverhead fish are so smart, they’ve learned to recognize what they mean. My exception to the rule is downstream of Hennebery or Pipe Organ Bridge where I’ve had some success blind-casting terrestrial and caddis patterns while floating in the evening and early morning.

Common tippet sizes range in the neighborhood of 3X through 6X. That said there’s a price to pay for going light, and finding a balance between hooking fish and not breaking the line is sometimes tough. There is also the issue of overplaying fish. While the last thing you want is your 6X tippet to snap while fighting a 22-inch brown that just sipped your spent Trico, a 20-minute battle isn’t healthy for the fish.

When it comes to hatches on the Beaverhead, one noteworthy improvement over the last few years is the abundance of mayflies

Baetis hatches seemingly begin and end the fishing season on the Beaverhead. In March through May and again in early fall they’re one of the most sought-after food items both above and below the surface. Size 16-20 Pheasant Tail Nymphs imitate the river’s tiny Baetis nymphs and are by far one of the most popular patterns on the river, but in recent years some other imitations like the Split-Case BWO have come to the forefront.

Caddis are another prevalent species up and down the river. In the summer they can hatch by the thousands in the evening after many anglers head t back to their lodges; so if you want to make the most out of your trip, eat dinner early and return to the river until dark (but bring mosquito repellent) for some good dry-fly fishing. It shouldn’t be a problem seeing rising fish, but enticing them to strike is sometimes tricky.

Stoneflies, while not considered a signature hatch on the river, squirm out of the rocks in July. Nymph patterns take most of the trout, but if you pitch some low-riding dry patterns among the willows and banks while the early season water levels are at their highest, you can turn heads. Look to the lower river from Pipe Organ to Dillon for some of the best action.

Midges, PMDs, and terrestrials round out the peak-season selection. If you bring an array of attractor and specific nymphs like Copper Johns, Barr Emergers, Hare’s-Ear Nymphs, and of course, the San Juan Worm (and variations like Silverman’s Sparkle Worm) you can cover most bases. I like to fish two flies separated by 16 to 20 inches of tippet and a small indicator set at 11/2 to 2 times the depth of the water I’m dredging. Reaching the bottom is crucial, so if my bugs aren’t bouncing off the rocks, I’ll add a small piece of weight above the point fly, but this usually only occurs when I’m running through the deepest, fastest water.

Next to caddis, Tricos are a favorite hatch on the Beaverhead. Appearing some time around the middle or end of July, they offer somewhat consistent morning action well into September. If you want to hit the meat of the hatch, get on the water as early as possible. As the sun rises you’ll start to see bugs dancing and have some areas of the river all to yourself. This will also help you beat the wind—a sometimes nasty element of the valley that can shut down the best Trico action in a matter of minutes.

Even though the Beaverhead is a tailwater, you won’t always be fishing flies size 18 and smaller. In the late summer, crane flies also start darting across the surface. Resembling mosquitoes on steroids, these leggy bugs skate across the surface of the water and provoke some violent surface strikes from the river’s browns. Nymphs like Barr ‘s Crane Fly Larva work well under the surface. Above the waterline, some say you can get away with an assortment of patterns, including locally tied custom flies available at the fly shops, as long as they’re actively fished.

Streamers have their place on portions of the river. Don’t expect to bounce them behind boulders and near logjams like you would on the Blackfoot or Big Hole. Instead, look for undercut banks and soft water between the middle of the river and shore.

 Because it is a tailwater, the cold water from the reservoir makes it different from most other rivers in the state—freestone rivers susceptible to warming and closures. Even on 100-degree days, the Beaverhead fishes. It’s never too hot to fish the Beaverhead. This tailwater delivers insect action throughout pretty much any day of the year. I’ve been on the Beaverhead when the summer days are so hot I can’t even find relief in the shade, so why torture myself? When it’s burning into the high 90’s and the sun is high, I like to limit my time on the water to the early morning and evening hours. I don’t have to fight the crowds through the meat of the day, and I don’t become burned out from sunrise to sunset marathon sessions. Instead, I fish until sometime between lunch and mid-afternoon and then grab a stool at the Buffalo Jump Saloon on the hill overlooking the dam. It’s a great place to enjoy the air conditioning, get a drink, a bite to eat, and recharge my batteries. Once the sun starts to set, I head back to the water and finish off the day.


1-15 connects the town of Dillon with both Clark Canyon Reservoir and the Beaverhead River. To reach access points, look for the frontage road (also called High Bridge Road) just east of exit 44 off 1-15. This road drops down into the valley and leads you to High Bridge, Henneberry, Pipe Organ, and Grasshopper, but you can get into the river wherever it bumps into the road, like “the slick” between Buffalo Bridge and High Bridge (just make sure you pull completely off the shoulder first). To reach the access below the dam, head northwest across the dam from exit 44, and take the first right. The dirt road winds down to a camping/recreation area at the base of the dam.

The middle river access points include Corrals (no boat ramp), Barretts, Tash Bridge near Poindexter Slough, Cornell Park and Campground southwest of Dillon, West Park Bridge in Dillon, and Selway Bridge near Clark’s Lookout State Park.

Many of the access points for the lower river branch off MT 41 between Dillon and Twin Bridges. Heading north from Dillon you can reach Anderson Lane, Beaverhead Rock, Silver Bow Bridge, and the town bridge on the south side of Twin Bridges. The current is slow down here, so put in early or plan to stay late to complete such long floats.

No mention of the Beaverhead River would be complete without noting its important place in history. The Lewis and Clark expedition visited the area several times and recorded their observations in journals. The handful of parks, markers, and interpretive signs along the river valley signify each place’s importance as it relates to those historical events—including the Beaverhead Rock landmark recognized by Sacajawea in their search for her tribe.