Fly Fishing Sheridan Creek, Idaho: Island Park Quiet Water

A Spring Creek in Shotgun Valley

Sheridan Creek rises in Clark County, in the Shotgun Valley ranch country between Kilgore and Island Park, and runs east into Fremont County. Idaho Fish and Game maps it at 28.3 miles. It ends in the west arm of Island Park Reservoir, the big irrigation lake on the Henrys Fork.

The valley sits inside the Island Park Caldera, one of the largest volcanic craters on earth. The eruption that formed it, about 2.1 million years ago, threw out roughly 2,500 times the ash of Mount St. Helens in 1980.

The smaller Henry’s Fork Caldera nests inside it and is the rim you can actually see.

The caldera floor is about 6,000 feet, and the town of Island Park, at 6,293 feet, is the highest city in Idaho.

That elevation, plus snowfall about three times what the surrounding country gets, is why this is trout water at all. The ranch calls it a spring creek, and its manager credits powerful springs with keeping the water cold while the reservoir below it warms.

Most of the creek runs through Eagle Ridge Ranch, a working cattle ranch in the valley. The public reach is at the bottom, on national forest above the reservoir. This guide covers both. For more small waters in the region, see our Idaho secret waters guide.

Regulations (Checked September 2026)

Sheridan Creek is not named in Idaho’s 2025 to 2027 rule book. Fish and Game’s own planner page for the creek assigns it the Henrys Fork tributaries rule, because the creek feeds Island Park Reservoir and the reservoir counts as a section of the Henrys Fork.

Three notes. First, the winter rule is the one anglers miss. From December until late May every rainbow and cutthroat goes back, and only brook trout may be kept.

Second, cutthroat go back in summer too, under the no-harvest clause. Third, the bait and barbless rules that govern the Henrys Fork through Harriman State Park do not reach the tributaries. A fly rod is simply the better tool here.

The rule book in force is the second edition, dated 2026. If you want the rule confirmed for the reach you plan to fish, the Upper Snake Region office in Idaho Falls answers at (208) 525-7290. Private water on the ranch has its own terms, covered below.

The Fish: Unstocked Since 1993

Fish and Game last stocked Sheridan Creek in October 1993, with 1,500 Yellowstone cutthroat fry and 3,000 cutthroat-rainbow hybrid fry. Before that came a thousand cutthroat fry in 1984 and small plants of rainbows in the 1970s and 1980. Nothing has gone in since. Every fish in the creek today was born there or swam up from the reservoir.

The department’s survey of the creek, in 2002, found brook trout, rainbow trout, mottled sculpin, and redside shiners. It found no cutthroat, which suggests the 1993 plant did not take hold in the reach surveyed.

The ranch describes its water differently, and it fishes a longer reach. Ranch manager Steve Hyde, whose family founded Hyde Drift Boats, says the property has about seven miles of spring creek and Sheridan Lake to fish, with rainbows, Snake River cutthroat, and brook trout in the system, plus native chubs.

The ranch’s page for Sheridan Lake says the lake holds mainly Kamloops-strain rainbows. That is the lake, not the creek, and it is the ranch’s own account.

Brook trout are the one species every source agrees on. Idaho lets you keep 25 of them, and on a creek that also holds rainbows and may hold cutthroat, keeping brookies is good manners.

Ranch Water and Public Water

Eagle Ridge Ranch sits along the base of the Centennial Mountains and calls itself an Old West cattle ranch. Its fishing runs mid-May to mid-September, weather permitting.

Sheridan Lake is by appointment only, about 12 rods a day, fly fishing only and catch-and-release, with a few rowboats on request and no phone service at the lake. The lake covers about 200 acres, nearer 300 at high water, and averages about 10 feet deep with holes past 25.

The ranch’s number is (208) 558-0900. Book before you drive. Hyde says grizzlies are a regular sight there.

The public reach is the lower creek. Green Canyon Road, a dirt road on the Caribou-Targhee National Forest, runs along the west end of the reservoir and crosses Sheridan Creek on a wooden bridge. Park at the bridge and follow the creek downstream about a mile and a half to the shoreline.

The West End campground, a dispersed site on the reservoir’s edge with no toilets or water, is the nearest place to camp. The Forest Service lists stream fishing there.

The Reservoir Below

Island Park Reservoir is the reason the creek’s rainbows get big. The Bureau of Reclamation built the dam between 1937 and 1939 for the Minidoka Project. It stands 91 feet high and 1,250 feet long and holds about 135,000 acre-feet.

Fish and Game puts the reservoir at 7,280 acres and calls it a Recommended Fishing Water for kokanee and rainbow trout.

The department stocks it hard. In each of 2022, 2023, and 2024 it planted between 33,000 and 36,000 catchable triploid rainbows of 12 to 14 inches, with 29,000 more by the end of September 2025. Kokanee fry went in by the hundred thousand in 2021 and 2022. Its 2009 survey also found cutthroat, brook trout, Utah chub, and two suckers.

Fish and Game’s advice is plain: fish from a boat in summer, from the bank in spring and fall, and through the ice near the dam in winter.

The reservoir’s problem is water. Farmers on the Snake River Plain own everything stored behind the dam, and in a dry year the summer drawdown warms the surface and opens an oxygen-starved dead zone below. Fish get squeezed between the two. The Reservoir Fish Habitat Partnership says the fishery deteriorated for decades because of it.

The Henry’s Fork Foundation’s answer, with the Bureau, Fish and Game, and the 250,000-acre Fremont-Madison Irrigation District, is a water-saving program called Farms and Fish. Through the 2020 to 2023 drought it cut the annual drawdown by nearly 20 percent, and the partnership reports fish abundance more than 150 percent higher than in years without it.

Sheridan Creek is part of that science. In 2000 the foundation picked nine indicator sites to monitor for the long term: six on the Henrys Fork itself and one each on Henry’s Lake Outlet, Fall River, and Sheridan Creek. Crews measured them every year from 2001 to 2005 and planned a return round for 2015 to 2020.

Flows: A Small Creek With a Short Record

The only USGS gauge on Sheridan Creek ran from May 1935 to November 1940, in Shotgun Valley about ten miles west of the dam. Six years is a short record, but the shape is clear.

Source: USGS gauge 13041500, Sheridan Creek near Island Park, monthly means 1935 to 1940.

This is a small creek. May runs ten times the winter base, and by September it is down to a few cubic feet per second. The fishable window is July through October, and the later you go, the lower and clearer the water. There is no active gauge, so plan by the calendar and the snowpack.

The reservoir follows the same calendar in reverse. The Forest Service warns that irrigation drawdown shrinks boat access at McCrea Bridge by August, so the mouth of the creek and the west arm can be a long walk across mud by late summer.

Getting There and Camping

The Ashton/Island Park Ranger District office is at 46 Highway 20 in Ashton, (208) 652-7442. Call before you count on McCrea Bridge, which the Forest Service listed as closed on its 2026 page.

This is grizzly country, and a Forest Service food storage order applies.

Food and garbage must be in an approved container or hung, and you may not camp within 100 yards of stored food or a quarter mile of a carcass. In the forest’s designated high-use areas, camping is limited to five days in any 14 from May 1 to September 1.

How to Fish It

Sheridan Creek is a meadow spring creek. Stay low, cast from the bank, and lead the fish. A 3- to 5-weight rod and a floating line cover it. Small dries pick up brook trout and rainbows all summer, and from August the hoppers along the grass banks bring up the better rainbows.

On the public reach, fish down toward the mouth. That is where creek fish and reservoir fish overlap, and Fish and Game says the reservoir’s own bank fishing is best in spring and fall. A streamer swung through the deeper bends near the shoreline is worth a try.

Keep the brook trout, release the rest, and release everything from December through late May. Bear spray goes on the belt, not in the pack.

Two other quiet eastern Idaho streams pair well with a trip here: Moose Creek and Bear Creek. For a desert spring-creek contrast, see the Little Lost River.

Frequently Asked Questions

Where is Sheridan Creek in Idaho?

Sheridan Creek runs about 28 miles through Shotgun Valley, west of Island Park, from Clark County near Kilgore into Fremont County and the west arm of Island Park Reservoir. Most of it crosses Eagle Ridge Ranch. The public reach is at the bottom, where Green Canyon Road crosses the creek about five miles past the West End campground and a walk of about a mile and a half reaches the reservoir.

What are the fishing rules on Sheridan Creek?

Idaho Fish and Game applies its Henrys Fork tributaries rule. From December 1 until the Friday before Memorial Day weekend, every trout except brook trout must be released. From Memorial Day weekend to November 30 you may keep six trout, but no cutthroat. Brook trout have their own limit of 25 all year. There is no bait ban or barbless rule on the creek.

When is the best time to fish Sheridan Creek?

July through October. The old USGS gauge on the creek averaged 145 cubic feet per second in May and 6 in September, so the creek runs high through June and drops to a trickle by early fall. Ranch fishing runs mid-May to mid-September. Green Canyon Road is usually snowed in until mid-May, and Fish and Game says the reservoir’s bank fishing is best in spring and fall.

Is Sheridan Creek private?

Mostly. Eagle Ridge Ranch controls the upper creek and Sheridan Lake, and books about 12 rods a day, fly fishing only and catch-and-release. The lower creek near the reservoir is public. You reach it from Green Canyon Road on the Caribou-Targhee National Forest, where the road crosses the creek on a wooden bridge above the West End campground.

Sources and Check Dates

• Idaho Fish and Game, 2025–2027 Seasons and Rules, second edition (2026), Upper Snake Region: general limits, trout definition, brook trout rule, the Henrys Fork and Henrys Fork tributaries special rules, the Henrys Fork fishing map, and the regional office listing. Checked 10 September 2026.
• Idaho Fish and Game, Fishing Planner: Sheridan Creek (length, counties, 2002 survey species, stocking records, rules assigned) and Island Park Reservoir (acreage, description, 2008–2009 survey species, stocking records). Checked 10 September 2026.
• Eagle Ridge Ranch, “Sheridan Lake & Creek” and home pages: booking terms, rod limit, lake size, Kamloops rainbows, ranch location and season. Checked 10 September 2026.
• Wet Fly Swing, “Fly Fishing Sheridan Lake and Eagle Ridge Ranch with Steve Hyde” (Traveled podcast, episode 22): ranch water, species, daily limit, springs, grizzlies.
• Reservoir Fish Habitat Partnership, “Island Park Reservoir, Idaho” (Waters to Watch): drawdown effects, Farms and Fish program results, 2020–2023 drought. Checked 10 September 2026.
• Henry’s Fork Foundation, Science and Technology page: habitat assessment history and the nine indicator sites including Sheridan Creek.
• USGS gauge 13041500, Sheridan Creek near Island Park: monthly mean discharge and period of record, 1935–1940. Checked 10 September 2026.
• USDA Forest Service, Caribou-Targhee National Forest: West End Campground, Buttermilk Campground, McCrea Bridge Campground, and Island Park Reservoir pages (directions, facilities, fees, seasons, dam facts) and forest orders (food storage, camping limits). Checked 10 September 2026.
• Idaho Birds, “Island Park Reservoir” birding destination page: Green Canyon Road, Kilgore-Yale and Old Shotgun Road directions, the Sheridan Creek bridge and mouth. Checked 10 September 2026.
• Wikipedia: Island Park Caldera, Island Park Dam, Island Park (Idaho), Kilgore (Idaho).