July 01, 2018
By Boots Allen
The greater Yellowstone area is a storied land in the world of fly fishing. Even today, after more than a century of attention, it still draws an endless number of anglers every year. The names of this region's rivers the Firehole, the Madison, the Yellowstone, the Wind River, the Henry's Fork evoke visions of incredible fishing for wild trout.
In the Feb.-Mar. 2018 issue, author Paul Weamer wrote an excellent description of the Yellowstone River, which drains the north side of the park. Draining the southern end is another stream that in many ways is the crown jewel of fly fishing in the Greater Yellowstone Area. This stream is the Snake River, and it just may be the center of the cutthroat universe.
All rivers have certain traits that set them apart from other waters. This is certainly the case for Snake River. Flowing through the valley of Jackson Hole and alongside the Tetons, the Snake is unquestionably one of the most scenic rivers in the world. It also runs through an area of intense wildlife abundance rivaled by few others.
Despite the scenery, the most attractive element of the Snake is perhaps its trout population. Its remains one of those few major river systems where native cutthroat trout in this case Snake River fine-spotted cutthroat (Onchoryhnchus clarkii behnkei)”still dominate the ecosystem. This particular subspecies has experienced the same policies of mismanagement that wreaked havoc on many other streams and on native cutthroat throughout the West. Yet through it all, Snake River cutthroat continue to thrive.
Historically, cutthroat trout of any species were held in low regard throughout North America. They lack the aerial dancing of rainbows or the long, downstream runs of brown trout when hooked, and were therefore considered less formidable. Many fly fishers considered them opportunistic feeders that are too easy to catch. Some even claimed that, with the exception of the Lahontan strain, they were incapable of reaching the 20-inch mark.
These are old, tired arguments today, but such sentiments lasted well into the 20th century. In the late 1980s, a good friend of mine submitted exquisite images of cutthroats to a well-known fly-fishing publication. "We don't want photos of cutthroat trout," the editor told him flatly. "They're too easy to catch and don't fight."
Times have changed, but Snake River fine-spot cutthroat have always had some enthusiastic followers. As early as the 1950s, visiting anglers extolled the virtues of bulldogging cutthroats using the river current to their advantage. Ernest Schwiebert, in his encyclopedic, two-volume work Trout (1978), wrote of his post-WWII visits to Wyoming's Snake River, and the impressive battles he had with this native gamefish.
Many astute fly fishers have noted that while Snake River cutthroat might be easy prey with artificial flies in the main channels, they are exceedingly difficult to fool on the numerous spring creeks and slow-moving side channels found throughout the river valley. As noted writer Paul Bruun has stated, "I can show you some fine-spotted cutthroats that are going to be pretty damn selective about what they are not going to be selective about." Anyone who has fished the Snake's spring creek tributaries like Flat Creek are familiar with what Bruun is talking about.
Snake River, Top to Bottom
The entirety of the Snake River from its headwaters to its terminus at the Columbia River in Washington is approximately 1,070 miles in length. Wyoming's portion is about 120 miles, less than 15 percent of this distance. The Snake begins as a series of finger creeks flowing from the Continental Divide before coalescing into one stream in Yellowstone National Park. The river courses generally south, flowing through the valley of Jackson Hole, Snake River Canyon, and eventually into Palisades Reservoir and then the state of Idaho.
Most of the stream flows through public lands, including Yellowstone and Grand Teton national parks, Rockefeller Memorial Parkway, Bridger-Teton National Forest, and parcels of county and state lands. Only about 15 miles of the Snake flow through private land. If you are a defender and advocate for public land and public access, the Snake River might well be your poster child.
The vast majority of the river is an outflow from Jackson Lake Dam. Officially, the Snake is a tailwater. However, 5 miles below the dam, the Snake is fed by a large tributary called Pacific Creek. A mile farther downstream, another major tributary, the Buffalo Fork, enters the river. More tributaries continue to feed the Snake River all the way to the Idaho border, so the river fishes much more like a freestone stream. These feeder streams drain thousands of square miles of mountain range that receive between 300 to 600 inches of snow each year. They influence river levels and water temperatures on the Snake far more than the dam.
When the snow melts in the spring, runoff can be overwhelming. But the degree and duration of runoff varies from year to year. A big snowpack can result in runoff lasting well over two months. Light snowpack can result in a runoff of six weeks or less. Start time can also vary.
The average start of runoff is generally during the first couple days of May, but I have seen it begin as early as April 23 and as late as May 10. The warming air temperatures of spring dictate when runoff gets underway. When it happens, anglers can expect several weeks with visibility less than a few inches.
Runoff on the Snake River is what makes the 5-mile tailwater immediately below Jackson Lake Dam important. This is the one piece of stream that runs relatively clear year-round. With an average gradient of 4 feet per mile, it exudes a slow, intimate quality characterized by large recirculating eddies, seams, and long runs devoid of much structure.
At times, rising cutthroat seem to be everywhere. These fish have a lot of time to study what they are eating. Refusals are the norm. It is the perfect place to test those fly fishers who still believe that cutthroat trout are purely opportunists.
The stream gradient picks up significantly below Pacific Creek. Most reaches average a drop of between 16 and 25 feet per mile. The holding water also changes below Pacific Creek. The big eddies and long seams found below the dam are replaced by fast riffles, substantial drop-offs, braided channels, and lots of structure in the form of fallen firs and cottonwoods.
This is technical fishing, but not in ways you'd think. Slow approaches, light leaders, and highly imitative patterns are not necessarily required. What is more important is working tight current lines where trout hold. Inches matter. Don't expect a take to occur if you are a foot from your target. A good rule of thumb is to be no more than the width of a closed fist. Crosscurrent is another challenge. Working a seam may require your line and leader to be across two currents with different velocities. Drag is going to occur faster than you think. Having a deliberate presentation with the adequate amount of slack on the surface (to allow for a decent drift) is crucial for success.
At the southern boundary of Grand Teton National Park, a levee system channelizes the Snake River, impeding its ability to flow through the historical floodplain for 26 miles. No portion of the river has been more impacted by man's drive for development: Multi-million dollar homes now populate the former floodplain. The vertically impounded Snake rushes by at an alarming pace. You would think this would be no-go land for trout. Yet Wyoming Game and Fish Department data consistently shows this portion of stream holds the highest concentration and average size of cutthroat in the entire drainage. The fishing through this leveed tract reflects this fact. I have caught the majority of my 20-plus-inch trout here, and it is my favorite part of the Snake. And regardless of nearby property development, the abundance of elk, moose, and bears in this area is impressive.
The levee system ends just upstream of Bridger-Teton National Forest and Snake River Canyon. The gradient here relaxes noticeably. It averages around 12 feet per mile, and the holding water changes once again. The riffles here are longer, and the drop-offs are less abrupt. The banks are punctuated with large, submerged boulders. There are also deep ledgerock pools. All of this provides substantial holding areas for trout.
This is arguably the easiest part of the Snake to fish. Your target area is much wider than what exists upstream. I have observed cutthroat dart several feet from a current seam to take a nymph dropper. If I am looking for fishing that requires a little less effort, the Snake River Canyon is where I go.
Snake River Seasons and Hatches
The long, warm, sun-filled days of summer are hard to beat on the Snake. The river generally clears by the first week of July, and the larger cutthroat are finished spawning. Dry-fly fishing with larger attractors, PMD imitations, Yellow Sallies, and Green Drake patterns is the name of the game.
The Snake flows through two of the most heavily visited national parks in the U.S. as well as a top-ranked national forest for recreation. Around 3.5 million people visit the Jackson Hole area every summer between June and September. A fair number of them are fishing, so don't expect to have the river to yourself.
There's no reason to avoid the Snake this time of year, just realize that you will be dealing with some pressure just about anywhere you go, and you should be willing to share the water with fellow fly fishers looking for a quality experience.
September through November is locally recognized as the best time to be on the water. There is gorgeous fall foliage, much of the wildlife is migrating and easily sighted from the riverbed, and all the streams are low and clear. Heavy hatches of Claassenia stoneflies, Timpanoga hecuba (Great Red Quills), Paraleptophlebia adoptiva (Mahogany Duns), and October caddis occur throughout much of autumn. It makes for terrific surface action. The streamer fishing is also very good. The river is clear enough to see larger cutthroat chase your baitfish patterns.
This is also my favorite time of year to fish area lakes for spawning lake trout and the mouths of lake tributaries where brown trout stage in preparation for their fall spawning run. I dedicate several days each October and November to fishing Lewis Lake and Jackson Lake for these fish, which are not native species.
Best of all, the crowds dissipate significantly by the first week of October. It is possible to fish the rest of the year and see only a few other fly fishers a day. Some days you don't see anyone.
Winter fishing on the Snake River is a rather new phenomenon. Prior to 2004, all the local streams were closed to fishing in winter. Since then, more and more fly fishers are hitting the Snake to see what winter fishing offers. As in autumn, the Snake is low and clear. It is easy to see the fish you are targeting. Most cutthroat pod up in deep areas with relaxed currents. This is great water to fish #18-22 adult midge patterns for slow-rising trout.
When the fish aren't on the surface, streamer fishing is the name of the game. Small (#8-10) forage fish imitations on floating lines work better than larger patterns on sinking tips. A slow retrieve with long strips is the best way to go.
Some people assume that a ski town with Jackson Hole's reputation would be too cold and snow packed to offer comfortable, quality fishing. The truth is that the lower valley only receives about 65 inches of snow a year. Much of this melts off through the winter. What is more, the warm winters we are experiencing throughout the West are occurring in Jackson as well. We have 40-degree days with sunshine every winter month, and 50-degree days are not uncommon. Unfortunately, the trade-off is water temperatures in the upper 60s during late summer. It's definitely not good for coldwater fish, but it feels pretty comfortable during the winter. It's easier for the trout to survive the winter ice jams as well.
Spring is an off-the-radar time for fishing the Snake. Most of us on the water this time of year are locals, or visitors who know what pre-runoff fishing can produce. The river is low and clear. Cutthroat lose their winter lethargy and begin to feed more consistently as water temperatures warm. They are feeding heavily to build up the reserves needed for the spawning runs they make in numerous tributaries in May. Streamer fishing in March and April often outproduces the summer months.
Blue-winged Olives generate excellent afternoon surface action, especially on days with cloud cover and a little precipitation. But nothing is more anticipated than the first emergence of Skwalas. These medium-size stoneflies appear around the middle of April and peak the first week of May. It is the first chance of the year fly fishers get to cast large attractors to rising trout. You can count on fishing Chubby Chernobyl patterns or rubber-legged nymphs for a month until the Snake eventually goes into runoff in early May.
On the Rise
It's interesting to hear Snake River fly fishers of different generations debate the quality of the fishing now compared to 40 years ago. Old-timers rave about the lack of pressure back then, and the good numbers of fish in the system. A younger generation points to electroshock data that suggests in some cases the fish numbers are stronger now. They believe we are fishing in the Snake's golden age.
The Snake is unquestionably healthier now than what it was in the 1960s and 1970s. Flows from Jackson Lake Dam are today managed more progressively. Abrupt ramp-downs which left invertebrates and trout trapped in side channels to die almost never happen nowadays.
Catch-and-release has led to far less harvest than in previous decades. There has also been a lot of rehabilitation work done on spawning creeks and other tributaries. The result is a more balanced ratio in terms of size and age structure of trout. Forty years ago, a day of fishing often resulted in a bunch of 12-inch and smaller trout, with a couple of bruisers over 19 inches. Today, there is a robust population of 12- to 18-inch cutthroat, as well as a good number under and over that size.
Opinions aside, the Snake River continues to provide a fishing experience duplicated on few other waters. It can be challenging at times and, like most other quality trout streams, fly fishers must deal with angling pressure during a certain part of the year. But these challenges can be worth it. And even when trout are not cooperating, you are still fishing in one of the most stunning places you'll ever see.
Boots Allen is a fly-fishing guide and writer who lives with his wife and two kids in Victor, Idaho. His latest book is Finding Trout in All Conditions.