Flat Creek Fly Fishing

Flat Creek originates in the rugged Gros Ventre Wilderness east of Jackson on the National Elk Refuge. At this point it is a small mountain stream. After it flows down onto the flatlands of the National Elk Refuge, it picks up spring water, which provides an ideal environment for trout and their prey. Most anglers are drawn to this specific section of Flat Creek.

This meandering meadow stream has deep undercut banks that provide cover for the wild cutthroats. There are only about three miles of stream to wade.

Flat Creek is home to sizeable native Snake River cutthroat trout, a distinctively fine-spotted variation of Yellowstone cutthroat trout.

These fish can feed very selectively during abundant hatches, and will put a heavy strain on your light tippet as they run under the bank.

Much of the fishing is visual, as the fish rise often. There are plenty of nice fish in the 15- to 19-inch class, and fish up to 27 inches have been landed


There is plenty for the cutthroats to feed on in Flat Creek. When it opens in August, gray drakes will be on the water. The drakes can be imitated with a #14 Parachute Adams, but if you are getting refusals, a biot body Gray Drake will increase your odds. Gray drakes will last for a couple of weeks. As is the case with most of this stream’s insects, the hatches are most prevalent from midmorning through the afternoon.

Cold, frosty mornings are common in August and it may take a while for the cold-blooded fauna to become active. The midday hours can produce the best fishingr. Evening angling can be variable. Sometimes it is good, and other nights are slow.

Pale Morning Duns

Pale Morning Duns (PMDs) hatch through the month of August, making them the most important summer hatch. The hatch can start as early as 11 A.M. but typically begins in early afternoon. PMDs are #16-20 pale yellow or light olive mayflies. For the duns, try a Compara-dun, Sparkle Dun or PMD parachute.

When fishing Flat Creek, anglers often find success with a variety of fly patterns. Emergers and spinners are key components of the fly selection. A #16 tan soft hackle or an Everything Emerger are recommended choices for emergers. Additionally, a Parachute Rusty Spinner can be effective during the spinner fall. Some anglers prefer tying spinners with an upright pearl Krystal Flash post, which is easily visible in the shadows of undercut banks and mimics the insect’s clear wing. In cases where the parachute may not entice bites, trimming down the post and using it as a spent spinner is a useful tactic.

Occasionally, anglers may observe fish feeding on emerging nymphs. To address this scenario, using a Pheasant Tail Nymph suspended below a dry fly is a top choice, as indicators can sometimes spook the fish. Rainy days often bring heavy PMD hatches throughout the day, while afternoon thunderstorms can also lead to bug activity, requiring some angler discretion.


Cranefly activity is another exciting aspect of fishing on Flat Creek. During mornings or evenings, craneflies can be seen skimming the surface. Trout chasing these insects create noticeable rises. Effective flies for cranefly fishing include the Madam X and Orange Stimulator, which can be dead-drifted or skittered for a more thrilling experience. When skittering the fly, it’s advisable to use at least a 3X tippet to avoid break-offs during strikes.


August and September often bring evening caddis hatches, with dark-colored patterns like Peacock Caddis and Foam Wing Caddis in #14-16 being effective choices. In the fall, there may be a few October Caddis, and a #10 or #12 orange Stimulator is a suitable option. While it may not be a significant hatch, the larger size of the bug tends to attract attention.

Terrestrials & Hoppers

Terrestrial insects play a crucial role in Flat Creek’s ecosystem, making them important for mid-day angling. Warm and windy August afternoons, combined with the tree-less terrain, create ideal conditions for terrestrial fishing. Tall grass along the banks houses various landborn insects, including hoppers, ants, beetles, and more. Hoppers are relatively small, with artificial flies in #10-14 sizes being appropriate.

The deceptive currents of Flat Creek can pose challenges for precise presentations, but these cutthroat trout require it. To improve your chances, maintain a low profile, approach cautiously, and delicately lay down your line. Foam Wing Hoppers, Parachute Hoppers, or Henry’s Fork Hoppers are effective patterns, though trout can become cautious of hoppers after a few weeks of fishing. Using hoppers to locate fish and returning later with a smaller fly can be a successful strategy.

Cutthroat trout in Flat Creek exhibit a preference for ants and beetles, making these patterns excellent choices for searching or after refusals on other flies. Foam and rubber ants or beetles in #10-14 sizes are recommended. Smaller imitations may be required for minute flying ants. Attractors like Royal Wulffs, Royal Humpies, and small Madam X’s feature terrestrial-like profiles, making them suitable for blind casting to locate fish.

Mahogany Duns

Moving into September, mahogany duns become a significant hatch. A #16 or #18 Mahogany Dun Thorax or Compara-dun serves well for both duns and spinners. From mid-September to the October closing date, blue-winged olives emerge, with Sparkle Duns and Compara-duns (#18 through #22) being effective for duns. Olive soft hackles or Quigley Cripples are preferred choices for emergers. Inclement days are prime opportunities for these hatches, typically occurring during the warmer afternoon hours. As the season progresses, fish may start to gather in deeper wintering pools instead of frequenting the undercut banks of summer.

How to Fish It

These cutthroat trout have evolved their own strategies to outwit the many overhead predators. They will seek refuge beneath overhanging banks, where they emerge cautiously to feed before retreating back.  So use stealth when positioning for a fish.

The ability to locate fish and position oneself strategically for casting and concealment is paramount. Nearly every bend in the creek can hold a decent fish.  Be patient.  Settle into a good looking spot and wait for a feeding fish. If none are spotted, move on carefully.

Try not to cast is unless a feeding trout is in sight. While blind casting can yield results, the thrill of spotting and stealthily approaching is pretty much the rule of thumb here.

Flat Creek’s serpentine path creates intriguing hydraulics, creating challenges for achieving a nice drift. To counteract the current’s influence, lengthy, supple tippets are essential. Using a 9-foot leader with 3- to 4-foot 5X and 6X tippets for smaller flies, or 4X for hoppers, provides the best control. A 12-foot leader enhances drift quality and offers additional stretch to prevent tippet breakage. The use of a non-slip mono loop knot facilitates a natural drift by allowing the fly to move freely.

Closing the Gap

Maintaining a low profile and utilizing tall grass for camouflage is advisable. However, there are instances where standing up and adjusting one’s distance from the fish may provide a superior casting angle. The key is to minimize your presence in the fish’s field of vision while delivering a lifelike fly presentation. Neutral, earth-toned clothing is an asset, as bright colors can be easily spotted by both fellow anglers and vigilant trout.

Silent footsteps and circumventing the areas you plan to fish are imperative, as vibrations can transmit beneath the water’s surface and alarm nearby fish. Keep in mind that other anglers share these waters, so it’s essential to respect their space and avoid intrusive approaches. Minimize wading whenever possible, as unnecessary disturbance can startle fish and harm the underwater ecosystem.

A slower 9-foot 3- or 4-weight rod is the preferred choice for Flat Creek. Its length aids in mending and casting from a kneeling position, while its soft action minimizes the risk of light tippet breakage. Limit false casting to a minimum; instead, adopt a technique that involves positioning yourself, stripping out the line, executing a brief false cast, and then smoothly shooting the line. Employing reach mends and mastering line control will significantly enhance your angling success in this unique and captivating environment.


Flat Creek is closed to angling from November 1 to July 31 to protect waterfowl nesting areas, so opening day on Aug. 1 can be busy. After about a week, things calm down and remain steady for the rest of the season.

Access to the stream is through the National Fish Hatchery parking lot, three miles north of Jackson on US Highway 89, or at the highway pullout two miles north of Jackson.

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