From high‐country headwaters in Colorado the North Platte slices north through Wyoming, morphing into a succession of blue-ribbon tailwaters below Seminoe, Pathfinder and Alcova reservoirs. Legendary reaches such as Miracle Mile and Grey Reef churn out wild rainbows and browns that average 16-20 inches, with genuine 10-pounders landed every season. Reliable dam releases keep water fishable even during drought, and dozens of BLM launches create an easy day-trip escape for anglers from Casper, Cheyenne and Colorado’s Front Range.
**Upper Wild & Scenic (CO line → Saratoga):** cottonwood-lined freestone dotted with public islands and long prairie floats. **Miracle Mile (Seminoe Dam → Pathfinder Res.)**: a 5-mile boulder garden of cold, rich water famed for lake-run bruisers. **Grey Reef Tailwater (Alcova → Casper):** 40 miles of spring-creek-clear flats and riffles that hold >4,000 trout per mile. Each reach has well-signed BLM or WGFD sites and a mix of wade and drift-boat water.
Wild rainbow trout dominate Grey Reef and Miracle Mile, averaging 17 inches and often pushing 24; brown trout lurk tight to structure and eclipse 26 inches every year. Cutthroat show in cooler tributaries, while walleye and smallmouth creep into lower reservoirs. State sampling routinely records 3,000-5,000 catchable trout per mile in the tailwaters.
Winter midges and sowbugs keep trout feeding beneath shelf ice. April sees explosive baetis hatches, followed by wall-to-wall PMDs, yellow sallies and caddis in May–June. Summer brings inch-long golden stones and drifting terrestrials—hoppers, ants and Mormon crickets—especially after windy afternoons. Fall cool-downs trigger streamer attacks on olive or black leeches as browns stage to spawn. During runoff the famed “San Juan worm bite” reigns whenever visibility drops to green-tea hues.
A 9-ft 6-wt with floating line covers most nymph and dry-dropper duties; bring a 7-wt with 10-ft sink-tip for spring high-water streamer floats. Indicator or euro rigs with 6-8 mm glass beads, scud patterns and size-18‐20 tan midges are deadly year-round. Swinging two-hand Spey rods is popular along Miracle Mile glides—280-340 gr Skagit heads and 10’ T-11 tips turn over 4-in articulated patterns for trophy browns.
Miracle Mile’s Kortes campground island, Cardwell access, and the ‘Bridge Run’ near Sage Creek are perennial producers. On Grey Reef, don’t miss Government Bridge, Double D and Lusby—each offers easy put-ins and long riffle-run shelves for wading at <2,000 cfs. Upper river walk-ins at Six Mile Gap and Pickaroon deliver solitude and eager cutbows from June through early August.
More than 30 BLM and WGFD sites dot the Wyoming corridor. Key boat ramps include Routt, Six Mile Gap, Pickaroon, Bennett Peak and Treasure Island on the upper river; Miracle Mile’s Chalk Bluffs and Cardwell; and Grey Reef’s Government Bridge, Lusby and Robertson Road. Most launches lie 5–8 miles apart—ideal for half-day drifts. Pay attention to afternoon winds that can turn wide flats into white-caps, doubling float times.
Flies: #14-16 baetis and PMD split-case nymphs, #6-8 golden stone nymphs, #20 black / tan midge pupa, #10 San Juan worm, size-4 gold/olive articulated dungeons, and foam hoppers (#8). Leaders: 9-ft 4X for dries, 7.5-ft 0X for streamers, 10-ft 5X fluoro for nymph rigs. Felt or sticky-rubber soles with studs are mandatory on Greybull algae-slick rock; bring a wind-proof shell and buff—steady 20-mph gusts are common by noon.
The North Platte supports endangered pallid sturgeon downstream and houses robust native mussel beds in quieter side channels. WGFD promotes harvest of small walleye below Pathfinder to protect juvenile trout, and the agency’s Aquatic Invasive Species (AIS) program requires boat inspections May–Oct. Volunteers from Trout Unlimited’s Platte Valley Chapter help with spawning-bed surveys and annual river clean-ups.
Dam releases can spike flows 1,500 cfs in minutes—listen for sirens at Kortes and Grey Reef dams. Afternoon prairie winds regularly exceed 30 mph; anchor or row to wind-shadowed banks when white-caps form. Late-March shelf ice breaks loose and creates lethal sweepers; avoid anchoring under crumbling banks. Cell coverage is minimal between Miracle Mile and Alcova—carry a satellite communicator and file float plans.
**The Reef Fly Shop & North Platte Lodge** (Alcova) sits riverside with private ramps, lodging and daily shuttle service. **Platte River Fly Shop** (Casper) stocks custom Miracle Mile intruders and rents drift boats. **Four Seasons Anglers** (Laramie) offers upper-river guide packages and Euro-nymph clinics. All issue Wyoming licenses, AIS decals and real-time flow texts.
Pitch in with **Trout Unlimited Platte Valley** on bank-stabilization work, join **Wyoming Fly Casters** in macro-invertebrate monitoring near Casper, or volunteer with **Wyoming Game & Fish AIS crews** during summer inspection blitzes. Donations and data logs help safeguard this blue-ribbon powerhouse for future anglers.
Wyoming regulations for the North Platte River limit anglers to **three (3) trout per day/possession, with only one fish over 16 inches**; special Miracle Mile and Grey Reef reaches follow the same creel but are **artificial-fly-and-lure only**. All trout <20 inches must be released immediately on Grey Reef from Grey Reef Dam downstream 4.5 miles. A valid Wyoming fishing license and AIS decal (for all craft) are required. Always check the 2025 WGFD Fishing Regulation Brochure for in-season emergency changes before heading out.