Big Lost River
river in Idaho
The Big Lost River offers diverse fishing, from challenging spring creek-like conditions in its upper sections to larger river fishing below Mackay Dam. It's an excellent destination for anglers seeking solitude and big fish.
Conditions right now
No USGS gauge is linked to this water yet, so we can't chart flows.
What's working on Big Lost River
- 01Blue-Winged Olives and Pale Morning Duns are actively hatching, providing dry fly opportunities on calmer days.
- 02Egg patterns are becoming increasingly important as trout key into spawning activity.
- 03Subsurface offerings like nymphs and streamers are highly effective as water temperatures drop.
- 04Midges remain a consistent food source and should be fished deep in slower runs.
Past reports week by week
12 weeksWhat to tie on
Picked from reports, hatches and the season. Tap a fly for the recipe and where else it works.
October Caddis (Dry)
Matches the October Caddis hatch, often the largest caddis hatch of the year in many western rivers during fall.
Buy at AmazonWoolly Bugger (Olive)
A versatile streamer imitating leeches and baitfish, effective for aggressive trout in colder fall flows.
PMD (Pale Morning Duns)
Pale Morning Duns are actively hatching in fall, providing a key food source for opportunistic feeders.
Blood Dot Egg
Essential for fall egg season, targeting trout feeding below spawning fish.
Buy at AmazonTungsten Bead Pat's Rubber Legs
A heavy stonefly nymph, a year-round staple, excellent for getting deep to feeding trout in stronger fall currents.
Buy at AmazonFlashback Pheasant Tail Nymph
A classic and versatile searching nymph, mimicking various active aquatic insects and effective year-round.
Zebra Midge
Midges are a consistent, year-round food source, especially effective in colder fall water subsurface.
Buy at AmazonBlue-Winged Olive Comparadun
Matches fall BWO hatches on overcast days, a primary food source for selective trout.
Where to fish and who to ask
Darlington Area
Provides access to diverse stretches of the Big Lost River, including bends and riffles holding good fish.
Mackay Dam Tailwater
The productive stretch immediately below Mackay Dam, known for consistent flows and large trout.
Wildhorse Road Access
Access point for the scenic and less-pressured upper Big Lost River, offering excellent dry fly fishing.
Fly shops within 40 miles
Silver Creek Outfitters
Sun Valley Outfitters
Get Big Lost River reports by email
Save this water and we'll email you a weekly summary of conditions, hatches and what's working.
Idaho season by season
What changes on the water through the year, with the flies for each season.
Read before you go
Winter Fly Fishing: Essential Cold Weather Tips & Tactics
Master winter fly fishing with proven cold weather strategies, gear selection, and tactics for catching trout when temperatures drop.
Fly Line Types Guide: WF, DT, Running & Shooting Heads
Master fly line selection with our comprehensive guide to weight forward, double taper, running lines, and shooting heads for every fishing situation.
Best Fly Fishing Waders of 2025 – Breathable vs. Neoprene
Expert comparison of breathable and neoprene waders with top 2025 models for every budget and fishing condition.
Fly Fishing Pack vs Vest: Which Setup Is Right for You?
Compare fly fishing packs and vests to find the perfect gear setup for your angling style and fishing conditions.
Best Fly Fishing Sunglasses: Lens Color & Polarization Guide
Master lens color selection and polarization technology for superior vision and fish detection on the water.
Fly Fishing Nets – Rubber vs. Nylon & Why It Matters for Fish
The net you choose dramatically impacts fish survival. Here's why rubber nets are superior to nylon for catch-and-release success.
Quick answers
Common questions about Big Lost River.
What flies work best on Big Lost River?
Our top scored fly patterns for Big Lost River right now are Mother's Day Caddis (80% confidence), Zebra Midge (Black) (80% confidence), Pheasant Tail Nymph (80% confidence). These picks are scored from recent fishing reports, hatch data, and seasonal patterns.
What fish species are in Big Lost River?
Big Lost River holds Rainbow Trout, Brown Trout, Cutthroat Trout. See the species links on this page for fly recommendations and seasonal behavior for each.
What are current flow conditions on Big Lost River?
Live USGS streamflow readings for Big Lost River are charted in the sidebar of this page and updated automatically from the nearest gauge.
Is Big Lost River fishing well right now?
We publish a fresh bite report for Big Lost River each week based on recent on-the-water intel. The current report — with conditions, hatches, and what's producing — is on this page.