Free Resource · Updated 2026
The Gray Reef section of the North Platte below Alcova Reservoir is one of the most productive tailwaters in the West. Cold clear water releases from the dam maintain consistent temperatures, and the river holds large populations of brown and rainbow trout year-round.
North Platte River (Gray Reef) Hatch Calendar — Quick Reference
Gray Reef is well-known for producing large fish in numbers unusual for a western river. The consistent tailwater flows mean hatches happen on a more predictable schedule than freestone streams. Midges and BWOs fish well throughout the year, including winter.
PMD hatches in July are one of the highlights, drawing selective feeding from fish that can be picky about fly size and drift. Trico and hopper seasons overlap in August for excellent summer fishing. Mahogany dun hatches in September extend the dry fly season into fall.
The Gray Reef stretch is accessible from public BLM land. Wade fishing and drift boats both work well here. The canyon walls and high desert setting make this a visually striking place to fish.
See the full Wyoming Fly Hatch Chart for hatch timing across all of Wyoming's top trout streams.
Check Conditions Near North Platte River (Gray Reef)What to Fish
Baetis spp.
BWOs are the most important hatch at Gray Reef. They come off on overcast days throughout the year and fish key on them heavily. A good drift with a small parachute or emerger is essential.
Recommended: BWO Parachute #18-22
Ephemerella infrequens
PMD hatches in July produce some of the most technical surface fishing at Gray Reef. Fish sip PMDs with great selectivity. Match the hatch precisely and use long fine tippets.
Recommended: PMD Parachute #16-18
Tricorythodes spp.
Morning trico spinner falls in late summer draw fish into feeding lanes in the flat water. This is delicate fishing that rewards careful presentation.
Recommended: Trico Spinner #20-22
Chironomidae
Midges are the foundation of winter fishing at Gray Reef. Fishing a two-fly midge rig through tailout pools on cold clear days can produce surprisingly large fish.
Recommended: Mercury Midge #20-24
Common Questions
Gray Reef is located below Alcova Reservoir in Natrona County, Wyoming, about 30 miles southwest of Casper.
Yes. The tailwater below Alcova Dam maintains consistent temperatures that support fishing through the winter. Midges and BWOs are the primary winter patterns.
Gray Reef is known for above-average fish size. Browns and rainbows in the 16 to 20 inch range are common, with larger fish caught regularly.
FlyFishFinder combines hatch knowledge with live gauge alerts, Prime condition indicators, and real angler intel so you show up on the right day, not the wrong one.
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