What Henry's Lake offers and when to fish it

Henry's Lake sits just west of Island Park on the Idaho-Wyoming border and holds cutthroat trout and lake trout in cold, shallow water that rewards patience and the right technique. The lake runs roughly 15 miles long and averages 8 to 10 feet deep, with some holes reaching 40 feet — a shape that makes it different from most mountain reservoirs and demands different tactics. Spring and fall are the strongest seasons; summer heat pushes fish deeper and makes midday fishing difficult, while winter ice fishing draws a dedicated crowd from December through March.

The cutthroat here are native to the lake and grow to 18 inches or better. Lake trout (mackinaw) arrived through stocking and now dominate the deeper structure. Both species respond to trolling, still-fishing with live baitfish, and fly fishing in the shallows during early morning and evening. The lake's shallow profile means you can reach productive water from shore in many places, though a boat opens up the deeper holes and lets you cover more ground.

Key Takeaways

  • Henry's Lake averages 8 to 10 feet deep with a few deeper holes, so cutthroat and lake trout stay accessible from shore and small boats throughout the year.
  • Spring (April through May) and fall (September through October) produce the most consistent fishing; summer heat pushes fish deeper and makes midday slow.
  • Live baitfish — especially tui chub and small whitefish — outfish most other methods for both species, though trolling and fly fishing work in specific conditions.
  • Idaho fishing regulations apply on the Idaho side; Wyoming regulations apply on the Wyoming side, and the border runs through the middle of the lake.
  • Winter ice fishing is popular and productive, but ice thickness varies year to year and should be checked with local outfitters before heading out.

Spring and fall: the peak seasons

April through May brings the most reliable fishing of the year. Water temperature climbs from the low 40s into the 50s, and both cutthroat and lake trout move into shallower water to feed. Cutthroat cruise the flats and drop-offs in 6 to 15 feet of water, and they respond well to live baitfish drifted or cast near structure — fallen trees, rock piles, and the shallow bays along the north and south shores. Early morning and late evening are most productive, but overcast days often fish well throughout the day.

Fall (September through October) mirrors spring in many ways. Water cools back into the 50s, fish move shallow again, and the same techniques that worked in spring produce results. The difference is that fall fishing often lasts longer into the day — the sun angle is lower and water clarity tends to be high, so fish stay active later into morning and earlier into evening. October can be exceptional, especially if the weather stays cool and stable.

Summer (June through August) is the hardest season. Water temperature climbs into the 60s and 70s, and both species retreat to deeper water and the cooler inflows where springs feed the lake. If you fish summer, focus on the deeper holes — especially the basin in the middle of the lake and the area near the dam — and fish early morning or late evening when light is low. Midday is nearly dead.

Live baitfish and trolling techniques

Live tui chub and small whitefish (4 to 6 inches) are the standard baits and consistently outfish everything else. You can catch your own with a small net in the shallows, or buy them from Island Park outfitters. Fish them on a simple rig: a size 2 or 3 hook tied to 6-pound test, a small split shot 18 inches above the hook, and a barrel swivel to prevent line twist. Cast near structure and let the bait swim naturally, or drift slowly along drop-offs and let the wind move you.

Trolling works well for lake trout and larger cutthroat, especially in spring and fall when fish are more aggressive. Use a small spoon (Kastmaster, Krocodile, or similar in silver or gold) or a tube jig, and troll slowly along the drop-offs and deeper structure. A depth finder helps you stay in the zone — lake trout often hold 15 to 25 feet down, and you want your lure just above the bottom or suspended in the middle of the water column.

Fly fishing is productive in early morning and late evening when cutthroat move into the shallows. Use a 5 or 6-weight rod with a floating line and small streamers (Woolly Buggers in black or olive, size 8 to 12) or nymphs. Cast near the shoreline and along drop-offs, and strip slowly — cutthroat here are not aggressive risers, but they will chase a moving fly.

Where to fish: access points and structure

Henry's Lake has several public access points. Island Park Village Marina on the north shore offers boat launch, rentals, and supplies. The south shore has informal access near the dam and along Forest Road 227. The west end near the Idaho-Wyoming border has less developed access but can be productive and quieter. Check with the Island Park Ranger District or local outfitters for current conditions and any seasonal closures.

Structure is scattered but important. The north shore has shallow bays and drop-offs that hold cutthroat in spring and fall. The south shore near the dam has deeper water and is better for lake trout. The west end has rock piles and submerged trees that concentrate fish. The middle basin is deep and cold — productive in summer when shallower water warms up, but harder to fish without a boat and depth finder.

Idaho and Wyoming regulations: which side are you on?

Henry's Lake straddles the state line, and regulations differ on each side. The Idaho side (north and west) follows Idaho Department of Fish and Game rules. The Wyoming side (south and east) follows Wyoming Game and Fish rules. The border runs through the middle of the lake, and you need to know which side you are fishing to follow the right regulations.

Idaho generally allows year-round fishing with a valid Idaho license. Wyoming allows year-round fishing with a valid Wyoming license. Both states require a fishing license, and both have different bag limits, size restrictions, and tackle rules. Before you fish, check the current regulations for the state you are on — they change year to year, and fines for violations are steep. Local outfitters in Island Park can tell you which side you are on and what the current rules are.

Winter ice fishing

Henry's Lake freezes solid most winters, and ice fishing for cutthroat and lake trout runs from December through March. The lake's shallow profile means ice is usually thick enough by mid-December, but thickness varies year to year and spot to spot. Always check with local outfitters or the ranger station before heading out — they know current conditions and can tell you where ice is safest.

Ice fishing here is simple: drill a hole, drop a live baitfish or small jig, and wait. Cutthroat and lake trout bite steadily through the winter, especially in the deeper holes and along the drop-offs. Bring a shelter, a heater, and warm clothes — the wind can be brutal, and you may spend hours waiting for a bite. The payoff is solitude and consistent action when open-water fishing is slow.

Gear and outfitters

A 5 to 7-foot medium-action spinning rod with 6 to 8-pound test is standard and works for both species. If you have a boat, a small depth finder is worth the investment — it saves time and helps you stay in productive water. A net, tackle box, and polarized sunglasses round out the basics. If you do not have a boat, shore fishing is productive in spring and fall, especially along the north shore and near the dam.

Island Park Village Marina rents boats and sells tackle, bait, and licenses. Henry's Fork Outfitters in Island Park offers guided trips and can point you to current hot spots. Local fly shops in West Yellowstone (about 30 minutes south) stock flies and can advise on conditions. Most outfitters are closed or have limited hours in winter, so call ahead if you are planning a winter trip.

Frequently Asked Questions

Can I fish Henry's Lake from shore?

Yes. The north shore near Island Park Village and the south shore near the dam both offer productive shore fishing, especially in spring and fall. You will catch fewer fish than from a boat, but you can reach cutthroat in shallow water and do not need to pay for a launch or rental.

What is the difference between cutthroat and lake trout here?

Cutthroat are native, smaller (usually 12 to 18 inches), and stay shallower. Lake trout are stocked, grow larger (up to 30 inches), and prefer deeper water. Both are good eating, but cutthroat are more common in the shallows and easier to catch from shore.

Do I need a Wyoming license if I fish the Idaho side?

No. If you are on the Idaho side (north and west), you need an Idaho license. If you are on the Wyoming side (south and east), you need a Wyoming license. The border runs through the middle of the lake. Local outfitters can tell you which side you are on.

Is the ice safe in winter?

Ice thickness varies year to year and spot to spot. Always check with local outfitters or the ranger station before heading out. Most winters the lake freezes solid by mid-December, but do not assume — a phone call takes five minutes and could save your life.

What time of day is best?

Early morning (sunrise to mid-morning) and late evening (two hours before sunset to dark) are most productive year-round. Overcast days often fish well throughout the day. Summer midday is nearly dead — focus on early and late.