North Platte River Fly Fishing: Wyoming's Miracle Mile & Grey Reef

Quick Reference

What	When	Key Numbers
Grey Reef fishing	Year-round (spring best for numbers)	500-1,500 CFS ideal; 3,000-8,000 trout/mile
Miracle Mile fishing	Year-round (spring rainbows, fall browns)	400-1,200 CFS ideal wading; 3,200+ trout/mile
Guided float trips	Book by February for spring	$550-700/day (1-2 anglers)
Fall trophy browns	Mid-October through November	20-30" spawners; streamers and egg patterns
Fly shop	Platte River Fly Shop	7400 State Hwy 220, Casper, WY
Regulations	Single-point barbless hooks required (2026)	Artificial flies/lures only at Grey Reef

Overview

The North Platte River in central Wyoming holds two of the most productive tailwater fisheries in the Rocky Mountain West. The Miracle Mile, a 5.5-to-8-mile stretch between Kortes Dam and Pathfinder Reservoir, and Grey Reef, the 40-mile tailwater below Grey Reef Dam south of Casper, consistently rank among the top trout waters in the lower 48.

These are not scenery-first rivers. The landscape is high desert: sagebrush flats, sparse cottonwoods, and wind that will test your casting stroke. What they lack in postcard beauty they make up for in sheer biomass. Wyoming Game and Fish Department electrofishing surveys show 3,200 trout per mile at the Miracle Mile and up to 8,000 per mile in the upper Grey Reef. Fish average 16 to 20 inches, with legitimate shots at 10-pounders throughout the year.

Both fisheries owe their productivity to dam-controlled releases that keep water temperatures stable and nutrient-rich. Cold, oxygenated water from deep reservoir outlets creates ideal growing conditions for rainbow and brown trout, producing the kind of fish densities that draw anglers from across the country.

Location and Access

The Miracle Mile and Grey Reef sit roughly 35 to 50 miles southwest of Casper along Wyoming Highway 220. Casper is the nearest city with full services, including fly shops, lodging, and restaurants.

Getting There

• From Casper: Take Hwy 220 south. Grey Reef Dam access is about 30 miles; Miracle Mile is 50 miles.
• From I-80 (Rawlins/Sinclair): Take the Seminoe/Kortes Road north for roughly 40 miles to reach the Miracle Mile.
• Nearest airports: Casper-Natrona County International (CPR). Denver International (DEN) is about 4.5 hours south.

Miracle Mile Access

The Miracle Mile sits between Kortes Dam and Pathfinder Reservoir. Two main parking areas provide access:

• Engstrom parking area (east side): Modern restrooms and camping
• Guthridge parking area (west side): Modern restrooms and camping
• 14-day camping limit applies at both areas

The access road is unpaved and notorious for becoming impassable when wet. Plan on bringing a vehicle with decent clearance, and check road conditions before committing to the drive. Cell service is nonexistent along most of the Mile. This is remote water, so bring everything you need.

Winter note: Wyoming Game and Fish does not plow the access road or parking areas in winter.

Grey Reef Access

Grey Reef has considerably more access infrastructure:

• Grey Reef Access Area (at the dam): Barrier-free fishing pier, restrooms, boat ramp 0.5 miles downstream
• Lusby Public Fishing Access: Wade fishing and boat launch
• Government Bridge: Popular boat launch and wade access
• Trappers Route #1: Between Alcova Dam and Casper, with four campgrounds

Land ownership: Much of the Grey Reef corridor runs through private land. Wyoming law restricts access to the water itself, not the banks. Trespassing fines can run up to $250. Stick to public access points or float through private stretches in a drift boat.

Flow Windows

Both sections are tailwaters, meaning dam operators control flows. This is good news: you rarely deal with the unpredictable blowouts common on freestone rivers. The bad news is that flow changes can happen with little warning.

Grey Reef Flow Ranges

Flow (CFS)	Conditions
500	Winter base flow. Excellent wading, concentrated fish
500-1,500	Ideal fishing range. Good wade and float options
1,500-3,000	Summer irrigation releases. Float-only for most sections
3,000+	High water. Experienced guides only

Summer flows typically run 2,000 to 3,000 CFS during irrigation season. Winter drops to around 500 CFS. If you can time a trip, the transition periods (late September/early October and late March/April) often offer the best combination of moderate flows and active fish.

Miracle Mile Flow Ranges

Flow (CFS)	Conditions
400-800	Low but fishable. Great wading water
800-1,200	Sweet spot. Both wading and floating work
1,200-2,500	Higher flows. Wading gets dicey; floats are productive
2,500+	Experienced guides only. Flows have historically hit 10,000+ CFS

Track conditions in real time on RiverReports before making the drive, especially for the Miracle Mile. Burning an hour of dirt road only to find blown-out water is a hard lesson.

Key Sections

Miracle Mile

Despite the name, the Miracle Mile stretches roughly 5.5 miles from Kortes Dam downstream to the upper reaches of Pathfinder Reservoir. When Pathfinder is low, the fishable stretch can extend to 12 or even 15 miles.

Kortes Dam to the Bridge (2 miles): The steepest gradient on the Mile. Fast water pours through a canyon with pocket water, boulders, and defined pools. This is where the biggest fish tend to stack up, particularly near the dam outlet. Expect white-water conditions that require an experienced oarsman if you're floating.

Bridge to Chalk Bluffs (2 miles): The river widens into a series of large shelves followed by deep runs. Classic nymphing water. Wade anglers do well here because the structure is readable and the bank access is decent.

Chalk Bluffs to Pathfinder (variable): How much river is fishable here depends on the reservoir level. In low-water years, this section opens up miles of additional water. The terrain flattens into sagebrush prairie, and the river character changes to slower, deeper runs. Productivity varies season to season.

Grey Reef

The Grey Reef tailwater runs roughly 40 miles from Grey Reef Dam downstream through and past Casper. The upper sections hold the highest fish densities.

Grey Reef Dam to Lusby (8 miles): The most famous and productive stretch. Fish density in this section runs 3,000 to 8,000 trout per mile depending on the survey year, with an average size of 17 to 19 inches. This is primarily float water on private land, though the Grey Reef Access Area and Lusby both offer wade access at the endpoints. Grey Reef Anglers estimates roughly 30 boats per day on a busy spring weekend, a fraction of what comparable tailwaters like the South Platte or Missouri see.

Lusby to Government Bridge (4 miles): Nice riffles at medium depth mixed with some longer, slower stretches. This section can get skinny at low winter flows. Decent wade access at both ends.

Government Bridge to Whitetail (2 miles): Rocky riffles where fish often hold in surprisingly shallow water, sometimes 12 inches deep. Fish here get less pressure because many anglers float right past.

Whitetail to Sechrist (10 miles): The longest continuous public access stretch on the river. Rocky riffles throughout. Good wade-and-fish water if you're willing to hike away from the access points.

Bessemer Bend to Robertson Road (8 miles): A fall favorite. Brown trout migrate to this section in October and November for the spawn, creating opportunities for outsized fish on streamers and egg patterns.

Seasons

Spring (March through May)

Spring is the marquee season for numbers. On the Grey Reef, thick Baetis (blue-winged olive) hatches fire up in March and build through April and May. Nymphing remains the bread-and-butter approach, but you'll get genuine dry fly windows during overcast afternoons when BWOs blanket the water.

On the Miracle Mile, spring means spawning rainbows. Fish in the 24-to-30-inch class run upstream from Pathfinder Reservoir starting in March. These are the biggest fish of the year, and they're focused on feeding heavily. Primary food sources include midges, leeches, scuds, and crayfish.

Spring also means wind. Persistent 15-to-25 mph gusts are the norm across this high desert country. Bring a 7-weight for wind management and a jacket that blocks it.

Important 2026 regulation: Grey Reef from the dam downstream to Ledge Creek is closed April 1 through May 15 to protect spawning rainbow trout.

Summer (June through August)

Summer brings the best dry fly fishing of the year. The Miracle Mile's golden stonefly hatch (roughly Memorial Day through late June) produces explosive surface takes. Stimulators, Sofa Pillows, and Pat's Rubber Legs in sizes 6-10 all produce. After the stones taper off, caddis and PMD hatches carry the dry fly action into July.

On the Grey Reef, summer hatches overlap: PMDs, Yellow Sallies, Tricos, and caddis all produce at various points. The best dry fly action comes at dusk during caddis flights and in the early morning during Trico spinnerfall. Midday fishing shifts to nymphs and small dry-droppers.

Grey Reef summer flows jump to 2,000-3,000 CFS during irrigation releases. This pushes most anglers to float rather than wade. Water clarity remains good unless tributary inflows (Bear Creek, Bolton Creek) muddy things up after storms.

Fall (September through November)

Fall is trophy season, especially for brown trout. Starting in mid-October, browns put on spawning colors and aggressive attitudes. They migrate to the upper Grey Reef sections and stage in predictable lies, creating the year's best opportunities for fish over 20 inches.

Streamer fishing peaks in late October and the first two weeks of November. Bring a 7-weight rod and a box of oversized patterns: Circus Peanuts, Woolly Buggers, Bunny Leeches, and Sculpzillas in olive, black, and white. Egg patterns also produce as both browns and whitefish begin spawning.

On the Miracle Mile, brown trout from Pathfinder Reservoir make their annual spawning run upstream in November and December. The same aggressive streamer tactics apply.

Winter (December through February)

Both fisheries remain open year-round, and winter fishing can be surprisingly productive for anglers willing to deal with cold temperatures and short days.

Grey Reef at 500 CFS winter base flow concentrates fish in predictable holding water. Midge hatches fire daily, and leech and scud patterns work well through the deeper runs. The fishing window is narrow (roughly 11am to 3pm when water temps nudge upward), but the lack of crowds is a genuine advantage.

The Miracle Mile is more challenging in winter. The unpaved access road may be impassable, and the remote location means no bailout options if weather turns. Come prepared for self-sufficiency.

Hatches and Fly Patterns

Season-by-Season Recommendations

Winter (December through February)

• Midges: Zebra Midge #20-22, Mercury Midge #22, Griffith's Gnat #18-20, Top Secret Midge #20
• Subsurface: Leech patterns #6-8, Scud #14-16, San Juan Worm #10-12
• Streamers: Woolly Bugger #6-8 (olive, black), Bunny Leech #4-6

Spring (March through May)

• BWOs: Parachute BWO #18-20, WD-40 #20, Sparkle Dun #18
• Nymphs: Pheasant Tail #16-18, Copper John #14-16, Hare's Ear #14-16
• Miracle Mile specials: Orange Blossom Special #14-16, Platte River Spider #14, Egg Pattern #12-14

Summer (June through August)

• Stoneflies (Miracle Mile): Stimulator #8-10, Sofa Pillow #6-8, Pat's Rubber Legs #6-8, Double Bead Peacock Stone #8
• PMDs: Pheasant Tail #16, Sparkle Dun #16, Comparadun #16
• Caddis: Elk Hair Caddis #14-16, Goddard Caddis #14
• Tricos: Trico Spinner #20-22 (mornings)
• Yellow Sallies: Yellow Sally #14-16

Fall (September through November)

• Streamers: Circus Peanut #2-4, Sculpzilla #4-6, Woolly Bugger #4-8
• Egg patterns: Nuke Egg #10-12, Glo Bug #10-12
• BWOs: Same spring patterns; fall hatches often stronger than spring
• Midges: Rojo Midge #20-22, Zebra Midge #20

The Local Patterns

Two flies originated on the North Platte and still produce consistently:

• Platte River Spider (#14-16): A soft-hackle wet fly that imitates emergers. Deadly swung through riffles during BWO and midge activity.
• Platte River Special (#12-14): A flashy attractor nymph. Works as a lead fly in a two-nymph rig on both the Mile and the Reef.
• Orange Blossom Special (#14-16): An egg/attractor pattern that's a staple on the Miracle Mile, especially during rainbow spawning season.

Ask for these at any of the local fly shops. They'll steer you toward the right sizes and colors for current conditions.

Wading vs. Float Fishing

When to Wade

Wade fishing works best during lower flows (under 1,000 CFS) and on sections with public bank access. The Miracle Mile offers the most consistent wade fishing because much of it crosses public land. On the Grey Reef, wade access is limited to the public areas at the dam, Lusby, Government Bridge, and a few other access points.

Bring felt-soled boots or studded rubber soles. The cobble bottom gets slippery, and the cold tailwater temperatures mean a swim is more than just uncomfortable.

When to Float

Float trips are the most productive way to fish the Grey Reef. A drift boat covers 8 to 16 miles of water in a day, giving you access to holding lies that wade anglers never reach. Most guided trips use StealthCraft drift boats that seat two anglers and a guide.

On the Miracle Mile, floating is feasible but more technical. There are no formal boat ramps, and the upper section below Kortes Dam has genuine whitewater. This is not water for a novice oarsman. Grey Reef Anglers and other experienced guides know the put-in spots and how to handle high-water conditions.

Regulations (2026)

The Wyoming Game and Fish Department implemented new regulations for 2026 that anglers need to know:

Hook Requirements

• Miracle Mile and Afterbay: Single-point barbless hooks required. Any bait, lures, or flies permitted.
• Grey Reef and Cardwell: Single-point barbless hooks required. Artificial flies and lures only (no bait).
• Pegged attractors prohibited at Fremont Canyon and Grey Reef.

Why the Change

A 2023 Wyoming Game and Fish study found that 21.4% of trout in the Miracle Mile showed visible hooking injuries. The barbless requirement aims to reduce damage to catch-and-release fish.

Grey Reef Spawning Closure

Grey Reef from the dam downstream to Ledge Creek is closed April 1 through May 15 to protect spawning rainbow trout. This is new for 2026.

Fly and Lure Zone Expansion

The artificial-flies-and-lures-only section at Grey Reef has been extended downstream to Government Bridge.

Commercial Guide Registration

Wyoming now requires all commercially guided fishing vessels to register annually ($325 fee), with visible registration documentation while operating.

Creel Limits

Miracle Mile: 3 trout daily, no more than 1 over 16 inches. Grey Reef area: check current Wyoming eRegulations for specific limits by section.

Gear Recommendations

Rods:

• 5-weight: Your primary nymphing and dry fly rod for both sections
• 7-weight: Essential for wind management (you'll use it more than you think), streamer work, and stonefly fishing on the Mile

Leaders and Tippet:

• 9-12 foot leaders tapered to 3X-4X for nymphing
• 5X-6X fluorocarbon tippet for clear-water midge fishing on the Grey Reef
• 0X-2X for streamers and stonefly dry flies

Other Essentials:

• Wind-blocking outer layer (seriously, the wind is relentless)
• Felt-soled or studded wading boots
• Wading staff for Miracle Mile cobble
• Quality polarized sunglasses (high desert glare is intense)
• Sunscreen and lip balm with SPF
• Cell phone charger (no cell service at Miracle Mile; plan accordingly)

Local Fly Shops, Guides, and Lodging

Fly Shops

Platte River Fly Shop (Casper): Operating since 1994, the longest-running fly shop and Grey Reef outfitter in the area. Located at 7400 State Hwy 220. Open Mon-Fri 8am-5pm, Sat 8am-noon.

The Reef Fly Shop (North Platte Lodge): The first permitted outfitter on the Grey Reef (since 1998). Located right on the river with lodging on-site.

Ugly Bug Fly Shop (Casper): Run by Crazy Rainbow Fly Fishing Guide Service. Full-service shop with guides for both Grey Reef and Miracle Mile.

Guide Services

Grey Reef Anglers: Experienced guides on both the Grey Reef and Miracle Mile. Float trips on StealthCraft drift boats.

• Grey Reef half day: $550/boat (1-2 anglers)
• Grey Reef full day: $675/boat
• Miracle Mile full day: $700/boat
• Miracle Mile extended (Bridge to Pathfinder): $900/boat
• Contact: 307-267-2559

Four Seasons Anglers: Guides the upper North Platte, Miracle Mile, and Grey Reef. Detailed hatch charts and fishing reports on their website.

High Plains Fly Fishing: Operates primarily on the upper North Platte and Miracle Mile. Float and wade trips available. Contact: 307-399-9464

Trout On Inn: Lodging and guiding combined, located 100 feet from the Grey Reef at Lusby. Offers drift boat rentals and shuttle service. Contact: 307-462-1917

Lodging

• Trout On Inn: Right on the Grey Reef. Guided packages with lodging and meals.
• North Platte Lodge: On-river lodging at the Reef Fly Shop location.
• Grey Reef Anglers Lodge: Full lodge operation with guides and accommodations.
• Casper hotels: Full range of options 30-50 miles from the fishing.

Book guided trips and lodging well in advance for spring (March-May) and fall (October-November). These are the prime seasons, and the best guides fill up months ahead.

Hazards and Safety

Wind: The single biggest hazard on both waters. Sustained 20+ mph winds are common, and gusts can reach 40-50 mph. This affects casting, wading stability, and hypothermia risk. Don't underestimate it.

Cold water: Tailwater temperatures stay in the 38-46°F range year-round. A wading slip in winter is a genuine emergency, especially at the Miracle Mile where help is far away.

Remote access (Miracle Mile): No cell service, no paved road, no nearby services. Carry emergency supplies, a first-aid kit, and let someone know your plan.

Spring spawning closure: Respect the new April 1 through May 15 closure on the upper Grey Reef. Fishing in closed areas puts the resource at risk and carries stiff penalties.

Private land: Stay in the water or at public access points. Wyoming trespass laws are enforced along the Grey Reef corridor.

Using RiverReports

Check current North Platte River flows on RiverReports before every trip. The tailwater character of both sections means flows can change based on dam operations, sometimes with limited notice.

What to watch for:

• Grey Reef at 500 CFS: Winter base flows. Best wading, concentrated fish. Check the Grey Reef flow page for historical comparisons.
• Miracle Mile at 400-1,200 CFS: Your wading sweet spot. Higher than 1,200 and you'll want a drift boat.
• Flow trends: A rising flow trend can indicate upcoming irrigation releases on the Grey Reef. Falling trends in fall signal the transition to winter fishing.
• Historical data: Compare current conditions to the 10-year average to gauge whether conditions are normal, high, or low for the time of year.

The flow data updates continuously, so you can make real-time decisions about which section to fish and whether to wade or float.