North Platte River - Grey Reef
Fly fishing in Wyoming · Intermediate · Best seasons: Spring, Summer, Fall, Winter
Target Species
Rainbow Trout, Brown Trout
About This Water
Blue-ribbon tailwater below Grey Reef Dam. Trophy rainbow and brown trout year-round.
Fishing Recommendations
Fly Fishing Guide: North Platte River – Grey Reef, Wyoming
Welcome to the "Reef." Located just outside of Casper, Wyoming, the Grey Reef section of the North Platte River is widely considered one of the premier tailwater fisheries in the world. Known for its massive average fish size and incredible biomass, this is where you go to catch hard-fighting, "football-shaped" trout.
🎣 Location Overview
The Grey Reef is a classic western tailwater that flows from the Grey Reef Dam through a high-desert landscape. What makes it special is the stability of the water temperature and the richness of the bug life.
Unlike many mountain streams, the Reef is a slow-moving, meandering river with a substrate comprised of gravel bars, weed beds, and deep runs. It doesn't look like "classic" trout water at first glance, but beneath the surface, the nutrient-dense water supports a staggering population of fish—often estimated at over 3,000 trout per mile. It is primarily a drift boat fishery, though wade access is available near the dam.
🐟 Target Species & Behavior
- Rainbow Trout: These make up the vast majority of the population. They are incredibly heavy for their length, known for aerial displays and long runs. During the spring spawn (March–May), they congregate on shallow gravel bars (redds).
- Brown Trout: While less numerous than rainbows, the browns here grow to trophy proportions. They are more predatory and tend to hold near the undercut banks and deep structure.
- Behavior: These fish are "well-fed." They don't move far for food because the current brings a constant conveyor belt of midges, scuds, and annelids directly to them. They often hold in "soft" water—the seams where fast and slow water meet.
📅 Best Times to Fish
Spring (March – May) - PRIME TIME
This is arguably the best time for sheer numbers. As the water warms, the fish become incredibly active.
- Window: April is legendary for the "Big Fly" bite.
- Condition: Watch out for the "Flush and Fill" (usually in late March), where the Bureau of Reclamation fluctuates flows to clear sediment.
Summer (June – August)
The river sees more weed growth, but the dry fly fishing picks up.
- Window: Early morning and late evening to avoid the midday heat.
- Condition: Trico hatches in July and August can provide world-class technical dry fly fishing.
Fall (September – November)
The "Second Peak." As the crowds thin out, the Brown trout begin their spawn and become aggressive.
- Window: October is prime for streamer fishing.
- Condition: Browns moving into the shallows.
Winter (December – February)
For the hardy angler, the Reef stays ice-free for miles below the dam.
- Window: 11:00 AM – 3:00 PM on sunny, low-wind days.
- Condition: Midge-only fishing. The fish are sluggish but still need to eat.
🪰 Recommended Flies & Techniques
Nymphing (The Bread & Butter)
90% of fish at Grey Reef are caught on sub-surface nymphs. Use a 9ft 6wt rod with a strike indicator.
- Scuds/Sowbugs: Ray Charles (Grey/Pink), Firebead Soft Hackle Sowbug (Size 14-18).
- Annelids (Worms): San Juan Worm, Red or Orange Wire Worms (Size 10-14).
- Midges: Zebra Midges, Manhattan Midge, Black Beauty (Size 18-22).
- Mayflies: RS2, Juju Baetis, Foam Wing RS2 (Size 18-20).
Streamer Fishing
Best in Fall or on overcast/windy days. Use a sink-tip line.
- Patterns: Goldie, Peanut Envy, Rusty Trombone, Articulated streamers in Olive or Black.
Dry Fly Fishing
Focus on the "slicks" and tail-outs.
- Patterns: Parachute Adams, Trico Spinners, Buzzball, Midges.
💡 Pro Tips & Local Knowledge
- "The Reef Rig": Local guides use a very specific rig—a 9ft 3X leader to a heavy split shot, then a 12-18 inch dropper to the first fly, and another 12 inches to the second. Adjust your depth constantly; if you aren't ticking the bottom, you aren't fishing.
- Wind is Your Enemy: Central Wyoming is notoriously windy. If the wind is gusting over 30mph, fly casting becomes dangerous. Always check the Casper wind forecast before driving.
- Avoid the Redds: In the spring, you will see bright, clean gravel patches. These are spawning beds. Do not walk on them or fish to the fish sitting on them. Target the "drop-offs" behind the redds where the non-spawning fish are waiting to eat drifting eggs.
- The "Miracle Mile": About 45 minutes away is another section of the North Platte called the Miracle Mile. If the Reef is crowded or off-color, "The Mile" offers a more rugged, brawling river experience.
⚠️ Important Information
Access
- The Dam (Public): The first few miles below the dam have good public wade access.
- Private Land: Much of the river below the first 8 miles flows through private ranch land. You can float through it, but you cannot drop anchor or step out of the boat onto the riverbed in many sections. Know your maps (use the OnX app).
Regulations
- License: Wyoming Fishing License and a Conservation Stamp are required.
- Creel Limits: Generally, the Reef is managed as a trophy fishery. Check current Wyoming Game & Fish Dept. (WGFD) regulations for "Special Management" limits, as they often require releasing most fish.
Safety
- The Sun: The high-altitude sun is brutal. Wear polarized sunglasses (essential for seeing fish/rocks) and high-SPF sunblock.
- Hydration: Bring more water than you think you need. The Wyoming wind dries you out faster than the heat.
Bug Hatches & Matching Flies
| Hatch | Type | Peak months | Time of day | Hook sizes | Matching flies |
|---|---|---|---|---|---|
| Midges Chironomidae | midge | January, February, March, April | All Day | #18-24 | Palotino Midge #20-22, Black Poison Tung #18-22, Morgan's Para-Midge #20-24 |
| Blue Winged Olives (Spring) Baetis | mayfly | April, May | Late Morning/Afternoon | #18-22 | RS2 (Grey or Olive) #18-22, JujuBaetis #18-20, Parachute Adams #18-22 |
| Pale Morning Duns Ephemerella | mayfly | June, July | Morning/Early Afternoon | #16-18 | Split Case PMD #16-18, PMD Sparkle Dun #16-18, Military Mayfly #16-18 |
| Caddis Hydropsyche | caddis | June, July | Evening | #14-18 | Elk Hair Caddis #14-18, LaFontaine's Deep Sparkle Pupa #14-16, Puterbaugh's Foam Caddis #16-18 |
| Yellow Sallies Isoperla | stonefly | June, July | Afternoon/Evening | #14-16 | Little Yellow Sloan #14-16, Iron Sally #14-16, Yellow Stimulator #14-16 |
| Tricos Tricorythodes | mayfly | August, September | Early Morning | #20-24 | Trico Spinner #20-24, Drowned Trico Spinner #20-24, Sunken Trico #22-24 |
| Blue Winged Olives (Fall) Baetis | mayfly | September, October | Midday | #20-24 | WD-40 #20-24, BWO CDC Emerger #20-22, Last Chance BWO #20-22 |
| Terrestrials Orthoptera | terrestrial | August, September | All Day | #8-14 | Amy's Ant #10-14, Rainy's Grand Hopper #8-12, Flash Beetle #14-16 |
| Crane Flies Tipulidae | midge | July, August | Morning/Evening | #8-12 | Crane Fly Larva #8-12, Daddy Long Legs #10-12 |