Fly Fisherman Throwback: Pre-Runoff in the Rockies

Editor's note: Flyfisherman.com will periodically be posting articles written and published before the Internet, from the Fly Fisherman magazine print archives. The wit and wisdom from legendary fly-fishing writers like Ernest Schwiebert, Gary LaFontaine, Lefty Kreh, Robert Traver, Gary Borger, Joan & Lee Wulff, Vince Marinaro, Doug Swisher & Carl Richards, Nick Lyons, and many more deserve a second life. These articles are reprinted here exactly as published in their day and may contain information, philosophies, or language that reveals a different time and age. This should be used for historical purposes only.

This article originally appeared in the May 1991 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Pre-Runoff in the Rockies."

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Runoff in the Rocky Mountains is a time when sunshine becomes increasingly stronger, and the snow that buried peaks, canyons, and high meadows melts with astonishing suddenness. From late May through early July, the melting snow flows down the mountains and into the streams, coulees, and valley-floor rivers. Many freestone rivers become high and discolored, "out of shape" for classic dry-fly fishing and wading. Some rivers might offer a chance encounter with a fast­paced salmonfly hatch, which requires that you pitch large weighted nymphs and drys along the bank cover from a drift boat, but the hatch is sometimes difficult to hit at the right time. Because of changes in weather and river conditions, regional experts figure visitors have a 25-percent chance of hitting the top stonefly action. Strangely, most touring anglers begin their pilgrimage to the West right in the middle of the runoff, and they are sometimes surprised at the high roiling waters, when the rivers in the East are low and clear.

Many anglers who prefer stalking rising trout with dry flies in clear water wait for the mid-July-through­ October period to fish the Rockies. Few fishermen realize, however, the great potential of the "pre-runoff season"–mid-March until the rivers begin swelling in mid-May. For those of us who live in the West, the pre­ runoff season is one of the best times to fish, both for superb match-the-hatch action and for some of the best big-fish streamer fishing of the season.

Surprising Conditions

The pre-runoff season is springtime, of course, but without the swollen waters you might expect. There can be mini-runoffs in hot spells; but the real runoff doesn't start until the deep high-altitude snow melts in late May and June. From March through mid-May the rivers are usually low, clear, and uncrowded. Geese nest along the rivers. Swallows return from their winter migrations, timed perfectly with the first Blue-winged Olive, Baetis, emergences. Hatches drift with the currents once again, and the trout begin their season of surface feeding with some degree of innocence. It's all that's needed to warm a dry-fly fisherman's winter-chilled blood.

The weather in the Rockies is always variable in the extreme. During the pre-runoff season temperatures can vary from a cheek-flushing 30 degrees Fahrenheit to a balmy, neoprene-sweating 85 degrees. While snow squalls do occur (precipitating great Baetis hatches), the weather is generally milder than most fishermen might expect, with daytime temperatures typically in the 40s to 60s and into the 70s in May.

Many of the tailwater rivers are at lower elevations (3,000 to 5,000 feet) and can have surprisingly warm weather. I get my first sunburn of the year in the pre­ runoff season. Even on a cold drizzly day, an after­ noon session with a Blue-winged Olive hatch, rising trout, and a thermos of hot coffee can be exhilarating on a river blooming with the promising life of spring­ time. While this is not the season to plan a family fishing vacation, it's a good time for traveling business­ men and adventurous anglers to start carrying their pack rods.

A Choice of Rivers

The wide choice of western rivers available to anglers is reduced during the pre-runoff season. Small streams and some rivers are closed to fishing. (Check local regulations.) Other high-altitude waters are still frozen.

The two major choices are whether to fish classic freestone rivers with their solitude and beautiful mountain scenery, or to fish tailwater rivers with their dependable conditions, high fish populations, and more fishermen.

Tailwater rivers such as New Mexico's San Juan, Utah's Green, Colorado's South Platte, Wyoming's Platte, and Montana's Bighorn offer the most reliable fishing in the pre-runoff season. The stable water conditions, large trout, high trout populations, and year-round fishing opportunities make these rivers the best bet for visiting fishermen with limited time.

Dependable hatches (as dependable as hatches can be) of midges and Blue-winged Olives give you the opportunity to stalk large trout with small drys, long leaders, and fine terminal tackle. This is not the chuck-and-chance-it fishing with a size 10 Royal Wulff that many visitors to the West used to practice. A polished match-the-hatch trout stalker can really shine. Good casting skills are often mandatory for a good day's fishing on the tailwater rivers when the selective trout are sipping midges and Baetis duns. When, no hatches are on, you need to use small nymphs fished with strike indicators. While this sort of fishing is not as aesthetically pleasing (or fun to me, anyway) as some other forms of fly fishing, the results can be superb in practiced hands.

Freestone rivers like the Gallatin and Yellowstone have their own special appeal during the pre-runoff season. The mountain scenery alone, with the high peaks still shrouded in snow, might be worth the visit to many. The rivers are less likely to have consistent dry-fly fishing, but they do offer a wider variety of insect types, including stoneflies (which tailwaters don't have many of), early-hatching fastwater mayflies, and free-roaming caddis nymphs, all of which means freestone-river trout often become "omniselective" during their midday feeding sessions.

If you enjoy casting large wet and dry flies and gazing about at the scenery (as opposed to watching a strike indicator or tiny dry fly all day), a freestone river could be your cup of tea. During spring, when a river's nymphal life is at its densest, midday nymph and wet-fly fishing can be fast and fun as you systematically work the runs and pocketwater. And midday hatches often occur in the quiet runs, pools, and tai­ louts, providing periods of dry-fly fishing.

Solitude is another benefit on the freestone rivers. Few fishermen are found there during the pre-runoff season. Since most of the freestone rivers (many of which are spring-fed) flow at higher altitudes, you can expect cooler daytime temperatures and a greater possibility of a snow squall-good trophy-brown-trout and hatch weather. Some freestone rivers will go out of shape due to prematurely hot weather and the resulting snowmelt, or because of heavy rains.

Tailwater Techniques

The techniques used on the tailwaters during the pre­runoff season are different from those used on the freestoners. Let's consider each separately.

Tailwater rivers generally have less diverse insect life, but they make up for it with the staggering numbers of insects present. This results in selective, well-fed trout. Midges and Blue­ winged Olives (Baetis) are the primary, and often the only, hatches to encounter on tailwaters in the pre-runoff season. The Olives hatch by the tens of thousands, especially on overcast, stormy days. Midges hatch throughout the day but have peak periods in the afternoon and evening, occasionally in the morning. Baetis are afternoon to early-evening hatches.

Sunny days have less Baetis hatching; the insects usually emerge toward evening to avoid the bright sunlight. Overcast days bring the Baetis out in force, from late morning until almost dark. (See John Gierach's article, "Blue­ winged Olives," in the December 1989 issue of Fly Fisherman.) This bonanza of size 16 to 24 mayflies and midges gets the trout into a rising rhythm that demands long fine leaders, accurate casting skills, and drag-free drifts (although twitching midge drys at the right moment can solicit rises from midge-oriented trout).

Dedicated trout stalkers who live for the far­ and-fine world of sipping salmonids will have a field day when conditions are right, those gray, invigorating days, when flotillas of blue­ gray wings and midge clusters drift down feeding lanes, bringing dozens of porpoising trout to the surface.

Four- to 5-weight rods from eight to nine feet long, double-taper lines with 9- to 12-foot leaders, and SX to 6X tippets are typical tools for this kind of work. Of course, short rods and the new ultralight 2-weights can be used, especially on calm days. They provide maximum thrills when you are stalking the risers. Popular dry flies to have on hand include Griffith's Gnats (size 16 to 24) for midge fishing, and olive Compara-duns and Parachutes, Adams, and Swisher/Richards·No-hackle Olives (size 16 to 18) for the Baetis hatch. Be prepared for windy conditions with nymphs and streamers, a sinking-tip line, and a 9-foot, 6- or 7-weight rod.

On sunny days when the hatches are sparse on the tailwaters, and during non-hatch periods, use Blue­ winged Olive nymphs-size 14 to 18 Pheasant Tails and Hare's Ears-size 18 to 24 midge pupa patterns, size 10 to 14 shrimp patterns, and San Juan Worms (size 18 to 24).

Fish the flies with a strike indicator and a dead-drift. Drop-offs, eddy lines, and converging currents are the prime areas to try. Have small weights, strike indicators, floatant, and dry-fly crystals on hand. You may have to fish at different depths during the course of the day. The trout might be anywhere from the sur­ face down to six feet deep or more, so adding and removing split-shot or Twist-ons becomes part of the daily routine as you prospect the depths.

I often use a two-fly system, especially when trout are intercepting emerging midge pupae. I use a small dry, a size 16 Elk-hair Caddis or Olive Parachute, for a strike indicator. It rides free on the leader, above the tippet knot (no dropper). At the end of a 12- to 20-inch tippet I tie on a midge pupa or a size 18 or 20 Pheasant Tail or Hare's Ear. Cutting off the nymph's tail makes it more realistic. Of course, you can use a specialized midge pupa pattern. This two-fly system gives the trout a choice of wet or dry fly–a school of trout may be feeding on both. Occasionally we catch two trout at once, providing some frantic moments of uncontrollable action.

Freestone Techniques

Freestone rivers have midges and Baetis, but they are often overshadowed in importance by larger fastwater insects. A variety of stoneflies, fastwater mayflies, and free-roaming caddis nymphs make up most of the freestone trout's diet in the pre-runoff season.

Big trout eat large stonefly nymphs year-round, as the Pteronarcys californica nymphs take two to four years to mature and are always available to the trout. Fish your nymphs dead-drift in all the fishy-looking freestone spots: cut banks, drop-offs, pocketwater, around larger boulders, and side channels. Use 7- to 9-foot leaders with 3X to 5X tippets. Many fishermen favor float­ ing lines and extra weight down near the nymph for this work. The Montana Nymph, Girdle Bug, Zug Bug, Hare's Ear, and Green Caddis Worm (size 6 to 12) are good prospecting patterns.

Western freestone rivers also have major hatches during the pre-runoff season. The little brown and winter stoneflies–Nemourid and Capnia–hatch as early as February and into May. Although these miniature (size 14) stoneflies are never abundant, I've seen midge-sipping trout go out of their way to take them as they caper across the surface.

A common pre-runoff-season mayfly to watch for is the Western March Brown, or Rhithrogena. This size 10 to 12 mottled-brown mayfly hatches in the early afternoon. "Rhithros" are found on freestone rivers and some tailwaters from March into May, depending on the altitude. This hatch brings trout to the surface and provides excellent nymph fishing. The nymphs are clingers and live in swift waters. It's hard to miss the duns, as they are one of the largest freestone mayflies of the season.

Finding specific imitative fly patterns for the rhithros is difficult; many local fishermen are not aware of the hatch. I don't know whether this is because few fishermen are on the rivers during the hatch, or if it is a lack of concern for matching the hatch. The hatch has been covered by many Western angling authors, including Rick Hafele and Dave Hughes in Western Hatches. A size 12 Adams with a tannish-brown body is a good imitation. Brownish Wulff-type patterns work well in broken water. Tan-bodied Parachutes with brown wings and grizzly hackle are good patterns for trout taking flies in quiet tailouts. While this hatch does not provide the long sessions of steady rising activity spurred by Baetis hatches (both on tailwaters and freestoners), it can provide an hour or two of dry-fly action.

The little Blue Quill (Paraleptophlebia) is another mayfly you might encounter on the freestone rivers. It is a size 14 to 16 slate-colored mayfly that resembles a Blue-winged Olive, but it is larger and darker. Blue Quills hatch for about two months in my area around Great Falls, Montana, beginning in early April, making them an important pre-runoff hatch. (Other Paraleptophlebia species hatch in summer and fall.)

Early Epeorus hatches, sometimes known as Little Yellow Mayflies, are size 10 to 14, cream to yellow to gray mayflies; the nymph has two tails, making them easy to identify. A Light Cahill is a fair imitation of this fastwater dweller. Epeorus nymphs can be imitated with a plump Hare's Ear or a tan soft-hackle flymph, while the darker Paraleptophlebia nymphs are better represented by a size 12 or 14 Pheasant Tail or an A. P. Black.

On Montana's Smith River, where I fish and guide many days during the pre-runoff season, Rhithrogena, Paraleptophlebia, Epeorus, and Baetis make up the bulk of the mayfly fauna in the spring. These freestone hatches, plus an assortment of stonefly and caddis species, provide observant anglers opportunities to catch hungry swiftwater trout. Carry attractor pat­ terns like size 8 to 14 Royal Wulffs and Trudes to round out your arsenal of freestone river flies.

The Mother's Day caddis hatch is a dense emergence that comes off when the water temperature approaches 50 degrees. (See "The Mother's Day Hatch," by Buddy Drake, in the September 1987 issue of Fly Fisherman.) Swift freestoners like the Yellowstone support the best hatches of caddis, which emerge by the thousands around Mother's Day-May 12. To be prepared for cad­ dis hatches, carry caddis emergers like soft hackles and Sparkle Pupae, and dry caddis patterns, including Elk-hair Caddis in sizes 12 and 14. By the end of May the freestoners are starting to rise with the runoff, and it is time to use big stonefly nymphs in the rising murky waters or head for a tailwater river for some clear-water fishing.

Streamers for Big Trout

For those inclined to chase large trout with streamers, the pre-runoff season is the prime time. Large Browns that spawned the previous October and November will be eating regularly and more often in the midday's warmth, rather than at night as is true later in the summer. They can be caught in shallower water, too–perhaps they are basking in the afternoon sun–though overcast days remain the best time. Their takes are vicious, exciting, and sometimes visible in the clear waters of spring.

Rainbows head for side streams and spawning beds throughout the pre­ runoff season. If you are persistent, you can catch large aggressive rainbows on streamers–Woolly Buggers and Spruce Flies–and egg patterns fished deep. The pre-runoff season offers the best opportunities of the year to catch large trout-both browns and rainbows-in tailwaters and freestoners, on streamers. It's often better than the more highly touted fall streamer fishing.

Proper Planning

When planning a spring trip to the Rockies, be prepared for any type of weather conditions. Take neoprene waders and felt-soled boots. The water will be cold and this is no time to go for a swim. Take long underwear, turtlenecks, warm shirts, pile jackets, raingear, gloves, and fishing and ski hats. Don't forget your polarized sunglasses, camera, and a thermos of hot coffee. Also take light shirts, sun­ screen, and lip balm. Occasionally the temperature gets into the 80s. In the clear mountain air sunburns come easy. Being prepared makes any weather extreme bearable, and even enjoy­ able. Enduring a snow squall that drives less enthusiastic anglers to the coffee shops can often reward you with moderating afternoons, profuse hatches, and rising fish, or perhaps a big brown on a streamer. It won't be long before the weather changes and again reaches its comfortable average in the 50s and 60s.

Most fly shops that guide on rivers in the Rockies are open and fishing the rivers in the pre-runoff season. Many of the guides are relaxing on the river, getting in some fishing, and discussing the latest techniques before the summer crunch. Be sure to call or visit various shops to get the latest information on the rivers you are considering. The best shops and outfitters will give you information, even if you don't book a guided trip. Helping visiting anglers is considered a major part of their business and good Western hospitality. Ask them about the fishing, hatches, weather, and river options in their area.

Whether you choose a tailwater river with its stable conditions, numerous large selective trout, and more challenging fishing, or a freestone river with its solitude, picturesque scenery, and omniselective spring trout, the pre-runoff season can start your trout­ fishing year off earlier and with some quality days onstream.

The fishing days and feeding sessions in the pre-runoff season may be a little shorter, and the weather more variable, but the fishing is good. At times it is as good as it gets. You don't have to wait for the salmonfly hatch and high water of June to fish the Rockies. When the swallows first return to feed on Baetis, midges, and Rhithrogena; when the geese are nesting and the buds blooming, you can find trout sipping quietly in the clear waters of springtime, before the runoff begins.

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E. Neale Streeks is a guide and freelance writer from Great Falls, Montana.

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