🏔 Eastern Idaho — Island Park / Yellowstone Plateau
Henry's Lake
Yellowstone Plateau — Trophy cutthroat and hybrids in the most productive stillwater in Idaho
6,000 acres
Surface Area
20 ft
Max Depth
6,472 ft
Elevation
Late May
Ice-Out
Jun, Jul, Aug, Sep
Prime Season
About Henry's Lake
Henry's Lake sits at 6,472 feet on the Yellowstone Plateau in eastern Idaho — one of the highest-elevation productive trout lakes in the Intermountain West and, by the consensus of stillwater fly fishers, one of the finest trophy trout lakes in North America. The lake's shallow (maximum 20 feet), nutrient-rich water grows trout at extraordinary rates, with fish averaging 18–22 inches throughout most of the season and fish over 25 inches encountered regularly by experienced anglers.
The fishery is dominated by three interrelated populations: Yellowstone Cutthroat Trout, Rainbow-Cutthroat hybrid (Cutbow), and Brook Trout. All three are wild, self-sustaining populations in excellent condition. The Cutbows in particular have developed into exceptional-looking fish — the size and colors of a large cutthroat combined with the fighting ability of a rainbow, averaging over 20 inches with exceptional specimens approaching 28–30 inches.
The lake's shallow, weedy character defines the fishing approach: float tube or pontoon boat, working the weed edges and channels with large leech patterns and Chironomid suspenders. The weed beds that cover much of the lake's floor are the key — fish cruise the edges of these beds actively feeding, and positioning a fly just off the weed margin consistently produces action.
Henry's Lake ice-out typically occurs in late May, creating a very compressed but intense fishing season from June through September before the early snowfalls of the Yellowstone Plateau close the roads in October.
Fishing Techniques
Float Tube / Pontoon
The standard approach. Work weed edges and channels. Suspended Chironomids over the deepest available water, or slow-stripped leeches and Woolly Buggers along the weed margins.
Boat Fishing
Small boats permitted with electric motors only in some areas. Allows coverage of more water. Troll Woolly Buggers along weed edges for large cutbows.
Shore Wading
Limited but possible in the northeast corner near the state park boat launch. Watch for the soft bottom — waders can get stuck in the fine silt.
Hatch Chart
| Chironomid/Midge | |
| Callibaetis | |
| Damselfly | |
| Dragonfly | |
| Leech (year-round) | |
| Scud |
Peak
Active
Absent
Fly Patterns
Chironomid/Midge
Henry's Lake Chironomid #10-14 · Red/Brown Chironomid #12-14 · Vertically Suspended Bloodworm #10-12
Callibaetis
Callibaetis Nymph #12-14 · Callibaetis Sparkle Dun #12-14
Damselfly
Olive Damsel Nymph #8-10 · Swimming Damsel #8-10
Dragonfly
Dragon Nymph #6-8 (olive/brown) · Gomphus #8
Leech
Woolly Bugger #4-8 (black/olive/brown) · Marabou Leech #4-8 · Mohair Leech #6-8
Scud
Orange Scud #12-14 · Olive Scud #12-14 · Pink Scud #12-14
Species
Cutbow Hybrid
The lake's most prized fish — a Rainbow-Cutthroat hybrid of extraordinary size averaging 20–24 inches. Wild and self-sustaining. Exceptional fighters on fly gear.
Yellowstone Cutthroat
Native subspecies present throughout. Averaging 18–22 inches. Classic Yellowstone strain with large orange slash marks. Cooperative leech and Chironomid feeders.
Brook Trout
Surprisingly large brook trout present, averaging 12–16 inches. Non-native but well-established. Best targeted with small bright streamers in fall.
Access Points
📍 Henry's Lake State Park
Northeast corner. Boat launch, camping, and day-use facilities. Primary access point. Idaho state park fees apply.
📍 West Shore
Less-visited west shore access via county roads. Float tube fishing with dramatically less competition on weekdays.
📍 Island Park Area
Multiple access points from Island Park — the small resort community that serves the lake. Float tube rentals available locally.
Pro Tips
- →Leeches are Henry's Lake's most reliable producer year-round — fish a size 6 black Woolly Bugger on a slow, erratic strip along the weed margins.
- →The silt bottom is dangerously soft near the shore — wear your float tube or pontoon boat rather than wading to avoid getting stuck.
- →Henry's Lake fish are famous for their size but the water can be frustratingly calm and clear — fish early morning and overcast days for the best action.
- →Combine with Henry's Fork below Box Canyon (20 minutes away) for the ultimate eastern Idaho stillwater + technical dry fly experience in a single trip.
Regulations
Idaho fishing license required. Henry's Lake has specific bag and size limits for cutthroat and cutbow hybrids — check Idaho Fish & Game carefully. State park fees at Henry's Lake State Park.