The River
Flowing out south-central Montana’s impressive Bighorn
Reservoir, the Bighorn River is truly a flyfisher’s paradise.
Considered by many to be one, if not the most productive
trout rivers in the world, the Bighorn hosts an average of
6000 trout per mile to backup its swagger. To add to this
astonishing figure is the fact that the average size of a
Bighorn trout ranges between 16-18" with 5 and 6 pound
lunkercaught with strikingfrequency. The river’s primary
attraction is the 13-mile stretch beginning below the
Yellowtail Dam at the town of Fort Smith. Ideal flows on this
length fall between2,000 to 5,000 cfs but fishing is still
productive up to 7,000 cfs. Anything above this benchmark
signals a swollen torrent with difficult fishing. The river
character is not unlike that of an enormous spring creek,
with undulating weed beds,deep holes, undercut banks, and
occasional riffles.River access is few and far between and
much of the adjacent land falls under the ownership of the
Crow Indian Reservation. This consideration, along with the
thick currents, makes the Bighorn a float river.The wading
angler can carve out some fishable water,but he is at a
severe disadvantage to the boater.The river can be floated
in segments as access points spread themselves out along the
rivers length: Yellowtail Dam/Fort Smith ("Afterbay Access"),
3 miles ("Three Mile Access"), 10 miles ("Bighorn Access"),
and 14 miles("St. Xavier Bridge Access"). Even the novice
boater can float this section without much problem as the
surrounding terrain is relatively flat resulting in a pleasant,
gentle, consistent current. Below the 14-mile access, the
Bighorn slow its pace and loses some its water quality and
clarity, resulting in lower numbers of trout. Despite this,
locals claim that this stretch, which continues to mile 29
("Two Leggins Access"), harbors the largest of the river's
trout, giant nocturnal browns tucked along the undercut banks
and nosing in the deep holes.
When
and How to Fish
So, what’s the hitch? Well, like any high-value resource, seemingly everyone wants a piece of the pie. High season on the Bighorn doesn’t refer to water levels, but to the intensity of fishing pressure which occurs in late summer. Bighorn rainbows spawn in late May and June (browns in November) and flyfishers generally let them take care of nature’s business. However, when the tricos begin to surface in August and the fever to land a 10 lb rainbow sets-in, the river can resemble a navy squadron training ground with obscenities and the occasional hurled projectile to boot. The most effective way to avoid this carnival is to hit the river before 8:00 a.m., giving you first access to sleepy-eyed trout. Otherwise, fish the river in the off-season. Fishing is productive 12 months out of the year.
The Bighorn is a veritable insect producing machine keeping its resident browns and rainbows fat and happy. The primary hatchesinclude the Caddis, Trico,Pale Morning Dun, Little Yellow Stonefly and Baetis,all of which fall in the size # 16-20 range. Baetis fishing can be productive from April to early June and then again in the fall between September and November. The hatches generally last from 11 a.m. to 5 p.m. with the highest intensity occurring atmid-day. Olive cripples or Parachute Adams will take fish on the surface, but the best fishing is to be had scouring the bottom with a weighted Hare’s Ear or Pheasant Tail nymph.
Mid-June marks the emergence of the Little Yellow Stone whose various imitations (Stimulator, Elk Hair Caddis, or Little Golden Stone nymph) will take fish consistently in riffles. PMD’s begin their emergence cycle in mid-July and remain active for about a month. During this period, nymphing with a Red Squirrel nymph can be very productive, as well as a PMD cripple on the surface. Evening spinner falls can be explosive and best results are achieved with a Rusty Spinner. As the little Yellow Stone hatch begins to taper-off in late July, the Tricos begin to take command followed shortly thereafter by the Black Caddis. The tricos (large by most standards) are an important hatch on the Bighorn as they lure up the monster rainbows after having recuperated from their spawning rituals. The Black Caddis hatch in August and September can be downright electric with the majority of the feeding occurring in the evening and deep into the night. In the off-season, or to break the rhythm a bit, midges, scuds, andtube-worms can be fished effectively throughout the year. Fishing deep on the Bighorn means 9-foot 4-6x tippets, one to two lead twisties, and, a strike-indicator. Given the numbers of fish and the presence of weed beds,long, arduous casting is not really an advantage. 35-45-foot casts with a 9-foot 6-weight with floating line should do the trick.
Despite the intense pressure, the Bighorn continues to live up to its preeminence in the flyfishing annals. Even a slow day on the Bighorn is equivalent to great day on most other rivers. That being the case, you can only imagine what truly great day must be like. If you enjoy the expansive breadth of Big Sky Country, emerald green currents, and the true likelihood of hooking into a giant two-foot rainbow, the Bighorn is the river for you.