3 Northern Rockies Trophy-Trout Rivers

You can drop a line in the North Platte, South Fork Boise and Beaverhead rivers, or you can fish them like a pro. Here are tips to get you on the water and catching plump rainbows quickly. (June 2009)

This heavy rainbow fell to a Pale Morning Dun emerger. PMDs are common hatches on all three rivers. Photo by Chuck Robbins.
Photo by Chuck Robbins.

Now is a great time to ramp up your knowledge of how to fish the North Platte, South Fork Boise and Beaverhead rivers to fish them like a guide this season.

NORTH PLATTE
The river above Saratoga flows through the Medicine Bow National Forest and gets high marks for scenic, wildlife viewing. It can be about as good as it gets -- bears, deer, elk, bighorn sheep and moose. And the trout fishing is pretty darn good, too.

If catching that trout of a lifetime is your goal, the better bet might be the two tailwater sections downstream: the famed Miracle Mile and the somewhat less well-known, though equally productive, stretch known as Gray Reef.

Miracle Mile
The Miracle Mile begins at Kortes Dam below Seminoe Reservoir and ends at the headwaters of Pathfinder Reservoir. The actual length varies from about five to eight miles normally. It can be double that in dry years. Regardless, the Mile is truly fertile habitat capable of producing monster trout. Biologists regularly sample trout in the 10-pound range, and rare individuals sometimes top 20 pounds!

The mix of browns and rainbows generally run 10-24 inches and probably average about 14 inches. But each season, anglers report catching trout in the 24- to 30-inch range. The biggest trout are spawners up from the reservoir: rainbows in spring, browns in fall. Many remain in the river long after spawning to provide what amounts to a season-long trophy-trout fishery.

While monsters certainly don't show up every time out, it isn't much of a stretch to say you can expect a significant fish anytime. And that, to my way of thinking, makes the Mile very special, indeed.

Alas, all is not perfect: Erratic summer flows, potentially foul and unseasonable weather anytime, heavy algae blooms and summertime crowds all can be frustrating.

Summer flows often yo-yo on a daily basis. Depending on irrigation demands, they can fluctuate between 300 and 3,000 cubic feet per second. Stable flows translate into more consistent fishing.

This is Wyoming, after all, so anglers should expect squirrelly weather anytime. As my friend, puts it, "Out-of-season weather."

If you spend any time on the water, you'll see that high winds and blizzards are common hazards that put a real crimp on even the best-laid fishing plans. Fickle doesn't even come close to describing High Plains weather. In my experience, any forecast beyond 24 hours isn't worth much. But there's not much we can do about weather, so pray for the best and expect the worst.

Algae blooms, or if you prefer, lettuce, in fertile tailwaters are, inevitable. Like the summer crowds, it's the price of doing business. Something of a pain in the butt? You bet. But the trout still have to eat. Put another way: Just deal with it.

With full public access, good water and more than ample trout numbers, finding a spot is not a problem even on the busiest days. Brown trout outnumber rainbows, but anglers report catching about three rainbows for every brown.

Nymphs and other wet offerings outfish dries by a wide margin, day in and day out. It's not uncommon to see a blizzard hatch with nearly every surface inch of river covered in bugs. During stable and low flows, dry-fly fishing can be excellent. The premier hatches are pale morning dun and baetis mayfly. Various caddis are also seen, as well as the little yellow stonefly and a variety midges.

Gray Reef
Much of what goes for The Mile holds true for Gray Reef. (Continued)

The blue-ribbon stretch that locals call The Reef begins at the base of its namesake dam. Home to trophy-size rainbow, brown and cutthroat trout, many consider it the premier rainbow tailwater in the country. It's a big low-gradient river. Its flows fluctuate seasonally between about 500 and 2,500 cfs to more than 5,000 cfs.

Unlike the often wildly fluctuating Mile, daily flows here are relatively stable. The fishing is more consistent, and for me, a more appealing destination. Because of limited public access, floating is best. But where it's legal, the friendly bottom makes for easy wading. (In Wyoming, whoever owns the stream bank owns the streambed; private lands require permission to beach the boat, drop anchor or wade.)

Rainbow trout average in the neighborhood of 17 to 18 inches. Jaded locals aren't likely to take a second look at trout under 24 inches, though I think most would agree anything beyond that is trophy class. Rainbows make up about 90 percent; browns and cutts make up the other 10 percent.

Nymphing is by far the method of choice. The preferred rig is two nymphs, 12 to 18 inches apart, weighted above with an indicator set about twice the depth of the water above that. Dead drift, on the bottom. Guides recommend at least a 9-foot rod for a 5- or 6-weight floating line.

Streamer fishing is also popular. It accounts for its fair share of the lunkers.

Both floating and sink-tip lines are useful. A somewhat stouter rod makes the chuck 'n' duck thing oh so much easier.

Dry-fly fishing is sporadic at best, but when the trout do decide to dine at the surface, it can be excellent.

Spring and fall see these hatches: baetis, PMDs, little yellow stoneflies, caddis, tricos and midges. For up-to-date info, check the local fly shops.

SOUTH FORK BOISE RIVER
The 28-mile stretch from Anderson Ranch Dam down to Neil Bridge at the top of Arrow Rock Reservoir teems with trophy-sized redband rainbow trout. Thanks to a recent invasion of juicy, trout-fattening Mormon crickets, larger-than-average trout are apparently on the increase.

The initial 12 miles below Anderson, a gravel road closely parallels the river. Access is easy, so it gets the most pressure. Below that, the river drops into a rugged and roadless canyon. From road's end to the Neil Bridge is about a 16-mile float. The canyon, especially in high water, contains some tricky white water.

Another option is a steep hike down from the canyon rim. Watch your st

ep because there are rattlesnakes. Regardless your modus operandi, this is a tailwater and fishes pretty much the same top to bottom.

Good fishing is almost a given no matter where or when you fish. The river boasts a higher-than-many body count. Rainbows as well as a smattering of bull trout and . . . drum roll please . . . a huge population of mountain whitefish. Don't laugh. South Fork trout can be moody, while South Fork bones, as they're called, are almost always willing.

One day last June, we could hardly buy a trout. But the SFBs were really on the take and saved the day. We hauled so many outsized bones our arms went limp.

SFBs aside, a single nymph on a single barbless hook is the most popular rig. Over the long haul, they tend to be most productive. Streamers fool some of the largest rainbows and almost all of the bulls. That said, heavy hatches often lure pods of larger-than-average rainbows to the surface.

For instance, one day we stumbled on just such a pod of rainbows, many in the 18- to 20-inch class, hungrily slashing the surface gorging on emerging caddis. While missed takes and long-range releases far outnumbered actual trout in the net, it was the kind of action that renders whatever happens next immaterial.

Hatches on the South Fork pretty much mimic those found on many other tailwaters: midges year around, BWOs spring and fall, stoneflies in June and July, and caddis June through October. But one hatch you won't see everywhere is the Pink Albert, a size 16-18 mayfly that appears toward the end of June and hatches into September. The local variations are probably the best imitators, but I've taken numerous trout during heavy Albert hatches with nothing fancier than a suitable size PMD. Even the lowly old Parachute Adams works in a pinch.

Hopper fishing in late summer and fall can be excellent. And ants work most anytime.

High water normally peaks in June. That's when fish often move into previously dry channels. You'll find challenging sight-fishing opportunities. This is prime time for pitching a dry-nymph dropper combination. I like to work upcurrent using a long, tapered leader and the stoutest tippet I can get away with based on conditions and size of fly. In other words, don't rig 5X if you can get away with 3X. The reason is simple: Big trout in shallow water are tough enough to handle without the handicap of gossamer tippets.

BEAVERHEAD RIVER
The "Beav," as we locals call it, is Montana's premier trophy-trout river. Not so long ago a local biologist excited the then-burgeoning devotee mob by announcing "a 20-inch trout for every 20 feet of river bank!"

Be that as it may, most would agree that when it comes to fat trout, the Beaverhead River ranks right up there. In my experience, there are very few days a noteworthy trout fails to show up. You might not get it in the net, but they are there.

The most popular stretch is from the dam downstream to Henneberry Fishing Access Site. It's a run of just less than 4 miles. It's all prime trout habitat and easily more water than you could effectively cover in a day, even from a boat.

The river is small and narrow by Montana standards. It's swift during irrigation season, which normally peaks June and July, when dam releases push flows into the range of 800-1,000 cfs.

Montana's wonderful Stream Access Law allows access to any moving water so long as it is gained from public land and as long as you stay below the high-water mark. But once flows top 500 cfs, wade-fishing becomes difficult to impossible. Above 500, floating is the more popular way to fish the Beav.

To maximize fishing opportunities, most guides use their boats more for transport as they get from run to run than actual fishing platforms.

The Beav is sinuous as a snake. It has brush-lined deep runs and undercut banks. At every bend, the river screams, "Big trout here!" And as happens more often than not, low and behold, a fat trout peels line at an alarming rate.

Trout shattered two of my high-end rods last season. That's what I get for trying to horse in big trout in heavy current.

Even more common is seeing an angler, statue-like, unable to move because of heavy current, hyperventilation, a little of both. His bent rod held high overhead, line peeling off the reel as a runaway trout races hell-bent for the Missouri.

Downstream of Henneberry, the crowds thin dramatically because of the popular notion that the trout downriver are smaller. While smaller on average is probably true, trust me, there is no shortage of fatties all the way to Twin Bridges, some 80 miles downstream. Be aware, however, that public access is fleeting below Dillon. In other words, lacking prior arrangements, do not launch or you just might find yourself spending a very long mosquito-filled night adrift.

It's known as a nymphing river, but if you play your cards right, the payoff just might be one the most fantastic dry flings imaginable.

For instance, last June we parked the boat on the bank beside the main channel and prepared to eat lunch. At the end of our break, I crept through the willow to the bottom of a weedy, slick-water side-channel. Voila! PMDs were hatching profusely. Lunker trout were up top munching down the moveable feast with gusto. We quickly de-rigged our nymphing outfits and rigged up dry-emerger tandems. Four hours later, the landslide vote was enough! How much fun can three fisher-folk endure, anyway?

As far I know, no one kept count, but each of us enjoyed numerous hookups and landed at least one trout in the 18- to 20-inch class. One of the browns was in the 24-inch range. So much for nymphs or nothing!

Over the years, I've noticed many mistakes by first-time anglers. The three most common are:1) Casting too far2) Not getting nymphs down deep enough, and3) Not fishing all the water.

Generally speaking, you are dealing with a lot of water in a confined space. When you're trying to cast across multiple currents, it's a sure formula for disaster.

Most runs are not only swift, they are deep, a combination that fairly screams for more weight than you might ordinarily be used to in more benign flows.

There's an old saw that goes something like this: The difference between a so-so day of nymphing and great day is often a single split shot. But my take goes something like this: If one is good, two is better.

Last but not least, all I can say is look around you. Note the river is all habitat, most of it primo or close enough. Cover all the water, fish it all. Some of the biggest trout often come from the most unlikely places.

Streamers are probably second on the popularity ladder. Keep in mind, early and late in the season, dark trumps bright almost every time. Just like fishing nymphs, hea

vyweights kill.

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