Wade4/100
Wading is the most sensitive plan today. Use protected edges only, avoid crossings, and downgrade quickly if clarity or current feels wrong.
All Idaho reports
Fly fishing report · West
Upper Lost River Drainage
Is Upper Lost River Drainage worth the trip today? Check flow, weather, hatches, access, and rules for Idaho before you go.
See the flow chart ↓Generated artwork: BlueStreamFly · Regional illustration; not the exact location.
Good day to fish?Latest river check
Poor
Not today. Make another plan.
39
Best option: Bank / edge. Bank and edge fishing is the safer default when water is high, pushy, or not fully verified.
See update time and confidence
Live data checkHighHow much of the live flow, weather, and alert data came back.
Today's callHighA verified hard stop is active, so the avoid-or-wait decision is clearer than the fishing score itself.
Score calculated Aug 22, 2026, 8:39 PM MDTUsually checks again about every 45 minutes
Best access methodBank / edge
These scores compare the risks of wading, bank fishing, and floating.
Bank / edge · Best fit21/100
Bank and edge fishing is the safer default when water is high, pushy, or not fully verified.
FloatNot recommended
This report does not recommend floating this reach.
Red Flag Warning issued August 22 at 1:41PM MDT until August 22 at 9:00PM MDT by NWS Pocatello ID
Your plan
Today's Upper Lost River Drainage plan.
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 smaller stream water, then check the Howell Ranch gauge and IDFG rules.
- Check first
- Use the Howell Ranch USGS gauge for upper drainage flow context.
- Try
- Separate upper drainage planning from the Mackay tailwater.
- Leave when
- 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.
Live river check
What the river is doing
Check the latest flow and weather before you go. A quick change can make the river harder or less safe to fish.
Showing the latest stored river check while current readings load.
- Flow
- 108 cfs
- From the latest stored river check. Open the official source for the newest reading.
- Air now
- 72°F
Current NWS forecast period
- Next 24h high
- 76.0°F
NWS air forecast near
- Rain chance
- 25%
For this forecast period
This is an air forecast, not a river-temperature reading. Check the water with a stream thermometer before fishing in hot weather.
Latest stored weather check
Chance Showers And Thunderstorms
Chance Showers And Thunderstorms
- Wind
- 7 mph
- Weather checked
Recent flow chart is loading
The latest stored reading is shown above. Check the official source below if you need the newest value now.
More forecast and source details
National Weather Service
Upper Lost Copper Basin forecast point
The National Weather Service forecast is temporarily unavailable.
Live data
Where these readings come from
Latest stored USGS gauge: Big Lost River at Howell Ranch near Chilly
From the latest stored river check. Open the official source for the newest reading.
How to fish it
How to fish Upper Lost River Drainage today.
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.
Fishing words used on this page
- U.S. Geological Survey (USGS) gauge
- A USGS gauge is an official river station that measures flow or water height.
- Cubic feet per second (cfs)
- Cubic feet per second, or cfs, shows how much water passes the gauge each second.
- Nymph
- A nymph is a young water insect. Anglers also use the word for a fly that copies it.
- Attractor fly
- An attractor fly is bright or bold. It draws a strike without copying one exact insect.
- Blue-winged olive (BWO)
- Blue-winged olives, or BWOs, are small mayflies that often hatch in cool or cloudy weather.
- Caddis
- Caddis are small water insects. The adults look a little like tiny moths.
- Emerger
- An emerger copies an insect as it rises from below the water toward the surface.
- Midge
- Midges are tiny flies and a common trout food, especially in cold water.
- Pale morning dun (PMD)
- Pale morning duns, or PMDs, are light-colored mayflies that often hatch in warmer months.
- Pocket water
- Pocket water is a small calm spot among rocks or fast current.
Why this call
Why this score
Public alertHurts
An active alert is in effect: Red Flag Warning issued August 22 at 1:41PM MDT until August 22 at 9:00PM MDT by NWS Pocatello ID. Check public safety sources before going.
Best mode nowHurts
Bank / edge: Bank and edge fishing is the safer default when water is high, pushy, or not fully verified.
Short-term weatherUse caution
The forecast has storm or heavy-precipitation risk, so timing and access matter more than the score alone.
FlowHelps
USGS shows 108 cfs. The flow has been stable over about 6 hours. USGS marks this reading provisional and may revise it. USGS records for this date (1904-2025, 117 readings) show a typical middle range of 102 cfs to 228 cfs. Flow is within the typical range for this date, so weather, temperature, and access become the next checks.
SeasonHelps
Summer: Prime high-country dry-dropper season when flows settle and temperatures stay trout-safe.
Trip notes
Trip notes
Check these before you choose a reach.
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 smaller stream, meadow, or headwater condition, so pair it with recent weather, snowmelt stage, and clear public access.
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.
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.
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.
What to try
Upper Lost River Drainage flies through the year.
Match the time of year, then let rising fish and current speed guide the next change.
SeasonWhat to look forFlies to try
Spring
What to look forMidges, BWOs, early caddis
Early summer
What to look forPMDs, caddis, small stones
Late summerCurrent
What to look forHoppers, ants, beetles, caddis
Fall
What to look forBWOs, midges
Each fly name opens its matching Fly Box guide.
Access and safety
Upper Lost River Drainage access and rules.
Use these places as starting points. Open the access link below and check posted signs before you park or enter. IDFG lists Big Lost River and smaller stream rules, including seasonal catch-and-release language and whitefish rules. Check the exact water before fishing.
Howell Ranch and Chilly area
Upper drainage flow-reference context with remote road planning.
Copper Basin
High-country approach with limited services and weather exposure.
East Fork Big Lost River
A separate IDFG-listed water with its own source checks.
North Fork Big Lost River
A remote smaller stream plan that should be checked against official rules and road conditions.
This is not one single managed river section.
Private land and public access can sit close together.
Roads can be rough, snowy, muddy, or far from help.
Use the below-Mackay page for the tailwater, not this upper-drainage report.
River sources
Official Upper Lost River Drainage sources.
Official agencies and primary river operators come first. Secondary tools are labeled so you know what carries the most weight.
How this report was checked
How this report was checked
Reviewed byBlueStreamFly River Review Team
Trip guidance checked
What was checked: This Upper Lost River Drainage report is maintained from USGS flow data, Idaho Fish and Game Big Lost, East Fork, and North Fork rule information, BLM access references, weather checks, and high-country Lost River planning guidance.
Live measurements and forecasts keep their provider timestamps. Rules, access, and trip guidance use the source-review date shown here. BlueStreamFly planning advice is editorial interpretation, not an agency notice.
First-hand experience: BlueStreamFly does not claim a first-hand visit or local field test for this report unless a real contributor is explicitly named and linked.
Rules and closures
Check what is allowed, where the rule applies, and whether the river is open.
Flow and weather
Check the latest river reading and forecast before you leave.
Access and land
Check public entry points, land rules, and seasonal access changes.
See all 6 checked sources
Rules and closures
Check what is allowed, where the rule applies, and whether the river is open.
What this source covers
Open the current rules and check the river section, season, and special limits.
What this source covers
Open the current rules and check the river section, season, and special limits.
What this source covers
Open the current rules and check the river section, season, and special limits.
Flow and weather
Check the latest river reading and forecast before you leave.
What this source covers
Open this page and check the latest safety advice before your trip.
What this source covers
Open this river reading to check the latest level, flow, and update time.
Access and land
Check public entry points, land rules, and seasonal access changes.
What this source covers
Open the land or access page, then check signs before you park or enter.
Quick answers
Quick Upper Lost River Drainage answers.
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.