Fly Fishing Dillon, Montana: Beaverhead River, Seasons and Local Pros
Location Details / Montana / Towns / Dillon
Fly Fishing Dillon, Montana: Beaverhead River, Seasons and Local Pros
Dillon is the town for the Beaverhead River, a reservoir-fed tailwater below Clark Canyon Dam that stays cool into August. Add Clark Canyon Reservoir, the lower Big Hole and Blacktail Deer Creek. Rainbows are catch-and-release on the whole Beaverhead, and the upper river opens the third Saturday in May. Fly into Butte (BTM).
Dillon is southwest Montana's ranch-country hub and the closest town to the upper Beaverhead, one of the state's most productive tailwaters. It pairs naturally with Twin Bridges downstream, and our Big Hole River page covers the freestone next door. For the state, see Fly Fishing Montana.
Top species
Brown and rainbow trout; mountain whitefish; burbot in Clark Canyon Reservoir
Best months
Late May to September on the upper Beaverhead; spring and fall below Barretts
Top nearby waters
Beaverhead River, Clark Canyon Reservoir, Big Hole River, Blacktail Deer Creek
License and regs
Montana FWP 2026 fishing regulations; nonresidents need a Conservation License, a fishing license and an AIS Prevention Pass
Nearest airport
Butte (BTM)
Closures
FWP waterbody closures: check the morning you drive
Rivers and Lakes Near Dillon
- Upper Beaverhead: Clark Canyon Dam to Barretts: The tailwater reach. FWP opens Clark Canyon Dam to Pipe Organ Bridge from the third Saturday in May through September 30; from the dam to High Bridge fishing access site it is artificial lures and single-pointed hooks, with browns and rainbows catch-and-release. Between High Bridge and Barretts Diversion you may keep 5 browns under 18 inches. Nonresidents may not float High Bridge to Henneberry on Saturdays from the third Saturday in May through Labor Day.
- Lower Beaverhead: Barretts Diversion to the mouth: Through Dillon and on toward Twin Bridges. FWP opens it April 1 through September 30, with browns and rainbows catch-and-release.
- Clark Canyon Reservoir: The reservoir above the dam. FWP allows 3 combined trout daily, plus burbot over 23 inches.
- Big Hole River: The lower Big Hole runs east of Dillon toward Twin Bridges. Below Dickie Bridge it is open April 1 to September 30, catch-and-release only. See the Big Hole page.
- Blacktail Deer Creek: A small Beaverhead tributary near town; FWP's combined trout limit here may be all cutthroat.
When to Fish Near Dillon
The Beaverhead is the drought hedge of southwest Montana: reservoir-fed, cool and mayfly-driven through midsummer, as John Radle explained on our Twin Bridges episode. Note the season dates in the FWP rules before you plan a spring or October trip. The chart is our reading, not agency data.
| Target | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Upper Beaverhead (open season) | ||||||||||||
| Lower Beaverhead (open season) | ||||||||||||
| Pale morning dun | ||||||||||||
| Caddis | ||||||||||||
| Terrestrials |
Intensity:LightModerateHeavy
Blank cells mean closed or not worth planning around. Read Hot Water, Hoot-Owl Closures, and When to Stop Fishing before a midsummer trip.
From the Podcast: A Low-Water Beaverhead Day
Missoula guide Michael Mathews told us about a March spring-break trip with his University of Montana teammates that ran from the Bitterroot to Dillon for a couple of days on the Beaverhead, then on to the Madison and the Henry's Fork. The Beaverhead was so low that the group would not let their rookie rower take the oars on it, a fair warning about how tight this small tailwater gets when flows drop. They were in Dillon the last night before Covid closed everything. John Radle, on our Twin Bridges episode, gave the other side of the Beaverhead's personality: in a hot, low-snow summer, this reservoir-fed tailwater is the water still worth driving to into August. Hear both in Life as a College Athlete/Fishing Bum and Bauer Reels: Get to Know the Angler.
Hire a Local Pro in Dillon
No Dillon guide, lodge or outfitter is in the FFIP Certified directory yet, so we won't name one we haven't vetted. On a small, technical tailwater with Saturday float rules for nonresidents, a local guide earns the fee. Find a Pro lists every pro we stand behind, and Frontiers International Travel can plan a full Montana lodge trip.
Tips from Podcast Guests
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Target staging fall browns with a two-handed jig-swing
A southwest Montana fall tactic. Check the regs first: on the Beaverhead, the upper and lower reaches close after September 30.
A Montana guide based in Twin Bridges, on the Fly Fishing Insider Podcast
Browse every tip in the Fly Fishing Tips Library.
Nearby Fly Fishing Towns
- Twin Bridges: Where the Beaverhead meets the Big Hole and Ruby.
- Ennis: The Madison's float town.
See every base on our Best Fly Fishing Towns in Montana page.
Dillon Fly Fishing Questions, Answered
Where can you fly fish near Dillon?
The Beaverhead River is the main draw: the tailwater from Clark Canyon Dam down to Barretts Diversion, then the lower river through Dillon toward Twin Bridges. Clark Canyon Reservoir sits above the dam, the lower Big Hole runs east of town, and Blacktail Deer Creek is a small tributary close by.
When is the best time to fly fish the Beaverhead near Dillon?
Late May through August on the upper river, which opens the third Saturday in May and stays cool on reservoir releases while freestones warm. PMDs and caddis carry early summer and terrestrials take over later. Under the 2026 FWP rules, Clark Canyon Dam to Pipe Organ Bridge and Barretts Diversion to the mouth close after September 30.
Do you need a guide to fish the Beaverhead?
Not legally, but it helps. The upper Beaverhead is small, brushy and fast, with float rules that close High Bridge to Henneberry to nonresident floaters on summer Saturdays. A guide handles the boat and knows the reach-by-reach tackle and harvest rules. Wade anglers can use FWP fishing access sites.
Is Dillon or Twin Bridges a better base?
Choose Dillon to be closest to the upper Beaverhead and Clark Canyon Reservoir, with more services in town. Choose Twin Bridges to sit where the Beaverhead, Big Hole and Ruby meet, with even reach to all three and the spring creeks. Either works for the other's water.
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Tight lines, everyone!
By Christian Bacasa, host of the Fly Fishing Insider Podcast. Last reviewed November 2026.
Seasons, regulations, closures and license requirements change, sometimes mid-season. Rules here come from Montana FWP's 2026 regulations or Yellowstone National Park at the time of writing. Confirm current rules with the agency, and availability with your Frontiers specialist, before you book anything.
Sources: Beaverhead, Clark Canyon Reservoir, Big Hole and Blacktail Deer Creek rules: Montana FWP 2026 Fishing Regulations. Closures: FWP waterbody closures. Beaverhead stories and drought strategy: Michael Mathews and John Radle on the Fly Fishing Insider Podcast.