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Fly fishing report · West
Upper Lost River Drainage
An Upper Lost River Drainage report for Copper Basin, Howell Ranch, East Fork and North Fork context, with USGS flows, IDFG rules, remote access, hatches, flies, and safety.
Check flow & weatherToday's fishing decisionMost live data available
39
Skip today
Do not commit until the safety issue clears.
Red Flag Warning issued August 2 at 1:04AM MDT until August 2 at 9:00PM MDT by NWS Pocatello ID
Best supported approachNo approach recommended
Watch nextRed Flag Warning issued August 2 at 1:04AM MDT until August 2 at 9:00PM MDT by NWS Pocatello ID
Updated Aug 3, 12:45 AM UTCUsually refreshes about every 45 minutes
Red Flag Warning issued August 2 at 1:04AM MDT until August 2 at 9:00PM MDT by NWS Pocatello ID
Safety overrides tacticsNo approach recommended
The active safety or closure reason takes priority over wading, bank fishing, and floating guidance.
Check before you drive
Current flow and weather.
Look at whether the river is rising or falling, then check wind, rain, and storms. These can change both safety and fishing.
Loading current flow and weather.
Before you rely on this report
How current is this report?
Conditions can change quickly. Check these dates before you decide to fish, and open the official source when safety or rules matter.
- River conditions
- Checked Aug 2, 2026, 8:45 PM
- Fishing guidance
- Reviewed May 31, 2026
- Public access
- No reviewed map pin available
- Rules and closures
- Official rule links checked
High confidence in the current score inputs.
6 sources are listed below for you to open.
4 public access records are listed. Private spots are never shown.
Source checked Jul 30, 2026
Plan your access
Know where you can enter.
These are public parking, launch, trail, or recreation areas—not secret fishing spots. We never show an angler's private pins, notes, or photos here.
- 0
- Shown on map
- 4
- No map pin
Location checkedDescription only
01No map pin
Roadside access
Howell Ranch and Chilly area
Upper drainage flow-reference context with remote road planning.
Restrictions and seasonal notes
This is not one single managed river section.
Private land and public access can sit close together.
02No map pin
Area description
Copper Basin
High-country approach with limited services and weather exposure.
Restrictions and seasonal notes
This is not one single managed river section.
Private land and public access can sit close together.
03No map pin
Area description
East Fork Big Lost River
A separate IDFG-listed water with its own source checks.
Restrictions and seasonal notes
This is not one single managed river section.
Private land and public access can sit close together.
04No map pin
Roadside access
North Fork Big Lost River
A remote tributary plan that should be checked against official rules and road conditions.
Restrictions and seasonal notes
This is not one single managed river section.
Private land and public access can sit close together.
How to fish it
Define the drainage before you fish it.
Upper Lost River Drainage is not one simple named reach. Treat it as a Big Lost upper-basin plan around Copper Basin, the East Fork, North Fork, and tributary water, then check the Howell Ranch gauge and IDFG rules.
- Use the Howell Ranch USGS gauge for upper drainage flow context.
- Do not use the below-Mackay tailwater gauge as the only upper-drainage decision point.
- Check IDFG rules for Big Lost River, East Fork, North Fork, tributaries, and whitefish language.
- Plan for rough roads, private land, and very limited services past Mackay.
Why the score looks this way
Public alertLowers score
An active alert is in effect: Red Flag Warning issued August 2 at 1:04AM MDT until August 2 at 9:00PM MDT by NWS Pocatello ID. Check public safety sources before going.
FlowHelps score
USGS shows 163 cfs with a stable over about 6 hours trend. Today's flow is within the normal seasonal range of 159 cfs to 374 cfs. Weather, water temperature, and access are the next checks.
SeasonHelps score
Summer: Prime high-country dry-dropper season when flows settle and temperatures stay trout-safe.
WeatherHelps score
The NWS forecast is about 81F with Patchy Smoke.
Fishing usefulnessHelps score
Skip or shorten the plan when roads are questionable, thunderstorms are likely, flows are too low or warm, dewatering makes fish handling risky, IDFG reach language is unclear, or legal access depends on crossing private land.
Read the water
What changes the plan.
The upper drainage is best when roads are open, runoff has settled, and water is cold but wadable. If the gauge is stale, roads are rough, or weather is building, choose a lower-risk river.
Cold stable high-country flow
Good for attractor dries, small nymphs, and short accurate casts.
Runoff
Avoid risky crossings and expect clarity and road access to be poor.
Low clear late summer
Use stealth, smaller flies, and stop if trout are stressed in shallow warm water.
Stale gauge data
Use extra caution and confirm conditions locally before driving deep into the drainage.
Your trip plan
Know when to go—and when to skip it.
Best flows
Use USGS 13120500 at Howell Ranch as the main live flow anchor. It helps with the upper drainage trend, but it does not settle every tributary, meadow, or headwater condition, so pair it with recent weather, snowmelt stage, and clear public access.
When to skip
Skip or shorten the plan when roads are questionable, thunderstorms are likely, flows are too low or warm, dewatering makes fish handling risky, IDFG reach language is unclear, or legal access depends on crossing private land.
Local plan
Pick one realistic target before leaving: Howell Ranch and Big Lost context for the best flow signal, East Fork or North Fork only after checking IDFG reach pages, or Star Hope and high-country access only when road and weather conditions support the extra travel.
Backup water
If the Upper Lost is dewatered, stormy, access-limited, or too remote for the day, compare the Big Lost River below Mackay, Big Wood River, or Silver Creek after checking current rules and flows.
Hatches & flies
Bring a flexible box.
TimingWhat to watchUseful flies
SpringMidges, BWOs, early caddisZebra midge, BWO emerger, caddis pupa, pheasant tail
Fly pattern · report suggests “Zebra midge”Zebra MidgeLook for a very slim tapered thread body, evenly spaced contrasting wire rib, a small bead, and no tail or wing. The reviewed classic is black with silver wire and a silver bead. Red, olive, brown, glass-bead, jig-hook, resin-coated, or tailed forms must remain labeled variations rather than replacing the classic identity.See photos & how to fish it ↗
Fly family · report suggests “BWO emerger”Blue-Winged Olive PatternsBWO describes a hatch group, not one fly. Nymph, emerger, dry, cripple, and spinner profiles must stay separate because they occupy different parts of the water column.See family guide ↗+ 2 more reviewed guides in the Fly Box Early summerPMDs, caddis, small stonesPMD dry, elk hair caddis, stonefly nymph, hare's ear
Fly family · report suggests “PMD dry”Pale Morning Dun PatternsPMD names an insect group, not one fly. Pale nymphs, trailing-shuck emergers, upright or low-riding duns, cripples, and spent-wing spinners stay visibly separate.See family guide ↗
Fly pattern · report suggests “elk hair caddis”Elk Hair CaddisLook for a tented elk- or deer-hair wing, clipped hair head, dubbed body, rib, and hackle palmered along the body. The body color should be labeled because tiers often match different natural caddis colors.See photos & how to fish it ↗+ 2 more reviewed guides in the Fly Box Late summerHoppers, ants, beetles, caddisHopper, ant, beetle, caddis, perdigon
Fly family · report suggests “Hopper”Grasshopper PatternsHopper patterns share a substantial body and long rear-leg impression, but foam, deer hair, wing construction, and waterline differ widely among named patterns.See family guide ↗
Fly family · report suggests “ant”Ant PatternsAnt patterns can be foam, fur-bodied, winged, or sunken. The narrow waist and paired body lobes matter more than one material recipe.See family guide ↗+ 3 more reviewed guides in the Fly Box FallBWOs, midgesBWO dry, RS2, zebra midge, small streamer
Fly family · report suggests “BWO dry”Blue-Winged Olive PatternsBWO describes a hatch group, not one fly. Nymph, emerger, dry, cripple, and spinner profiles must stay separate because they occupy different parts of the water column.See family guide ↗
Fly pattern · report suggests “RS2”RS2Start with the beadless architecture: two dark-dun Microfibett tails separated behind a slim, tightly twisted and visibly segmented dubbed abdomen; a fuller thorax; and saddle-hackle web clipped into a short angled wing bud. Rim Chung's original-style form uses natural beaver dubbing and hackle web. CDC- or Antron-wing ties, beads, curved hooks, flash, and tailless Avatar-style flies must remain labeled variations.See photos & how to fish it ↗+ 2 more reviewed guides in the Fly Box 01
Separate upper drainage planning from the Mackay tailwater.
02
Use maps to avoid crossing private land on the way to public water.
03
Fish small attractor dries and droppers through pocket water in summer.
04
Check roads and weather before committing to Copper Basin or side drainage travel.
05
Move on if low flows or warm water make trout handling poor.
Rules & closures
Check the official rules before you go.
Open the agency page to confirm the exact river section, species, season, tackle rules, limits, and emergency closures.
Official links checkedRules for this river or sectionNo special rule found
We did not find a special rule for this river.
We checked the state source but did not find a clearly supported exception for this river. Check the official rules for the exact section you plan to fish.
Rules checkedJul 30, 2026
Report a correction ↗Always follow the official rule
This summary helps with trip planning. The linked agency rule is the one you must follow.
Updates from anglers
What anglers are seeing.
Recent observations from general areas of Upper Lost River Drainage. We review every update before it appears and never publish exact fishing spots, private access details, or photo locations.
Angler updates are not loading right now.
You can still use the river plan above. Check back later for recent observations from other anglers.
Where this report comes from
Open the sources we checked.
Fishing guidance checked: May 31, 2026
Site check: Jul 14, 2026. We regularly test report links, live scores, flow and weather data, and page loading. The content date changes only when the fishing guidance or its sources change.
flowUSGS monitoring location: Big Lost River at Howell RanchregulationIDFG Big Lost River Fishing PlannerregulationIDFG East Fork Big Lost River Fishing PlannerregulationIDFG North Fork Big Lost River Fishing PlanneraccessBLM Big Lost River Access TrailsafetyNational Weather Service forecast point near Copper Basin
Common questions
Before you leave.
Is Upper Lost River Drainage one river?+
No. It is a drainage-style report for upper Big Lost, East Fork, North Fork, and Copper Basin planning.
Which gauge should I use?+
Use USGS 13120500 at Howell Ranch for upper drainage context, not the below-Mackay tailwater gauge.
Is access easy?+
No. Roads, private land, weather, and limited services all matter.
What flies should I start with?+
Use small attractor dries, caddis, PMDs, terrestrials, and tungsten droppers in stable summer flow.