7-day U.S. Geological Survey chart
Recent flow
Discharge
106 cfs95 cfs
Sep 5Sep 11
Latest reading: 95 cfs. Stable over about 6 hours. Chart covers Sep 5 through Sep 11; readings are provisional and may be revised.
All Idaho reports
Upper Lost River Drainage
Generated artwork: BlueStreamFly · Regional illustration; not the exact location.
Should I go fishing?
Check the water temperature first.
Water temperature is unconfirmed. Use a stream thermometer; stop trout fishing at 70°F or warmer, or sooner if fish show stress.
Fishing rating92
Rating updatedRiver local time:
Why this recommendation?
USGS shows 95 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, 116 readings) show a typical middle range of 85 cfs to 169 cfs. Flow is within the typical range for this date, so weather, temperature, and access become the next checks.
Available live dataHighHow much of the live flow, weather, and alert data came back.
Confidence in this recommendationMediumWater temperature not verified; do not use this score to clear warm-water risk.
Usually checks again about every 45 minutes
If you go
- 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.
Flow and weather
Showing server-checked river conditions while current readings refresh.
- Flow
- 95 cfs
- Stable over about 6 hoursU.S. Geological Survey may revise this reading
- Air forecast
- 53°F
- Next 24h high
- 71.0°F
NWS air forecast near
- Rain chance
- 0%
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
Mostly Clear
- Wind
- 12 mph
- Weather checked
More forecast and source details
Mostly Clear
National Weather Service
Upper Lost Copper Basin forecast point
The National Weather Service forecast is temporarily unavailable.
Live data
Where these readings come from
Current U.S. Geological Survey gauge: Big Lost River at Howell Ranch near Chilly
Stable over about 6 hoursU.S. Geological Survey may revise this readingObserved
Flies for this time of year
Seasonal starting points, not a live hatch report. Match what you see on the water.
- Grasshopper PatternsHopperView fly guide ↗
- Ant PatternsantView fly guide ↗
- Beetle PatternsbeetleView fly guide ↗
- Caddis Patterns by StagecaddisView fly guide ↗
- Perdigon NymphperdigonView fly guide ↗
See flies for every season
SeasonWhat to look forFlies to try
Spring
What to look forMidges, BWOs, early caddis
Early summer
What to look forPMDs, caddis, small stones
Late summerThis season
What to look forHoppers, ants, beetles, caddis
FallThis season
What to look forBWOs, midges
Each fly name opens its matching Fly Box guide.
More fishing tips
Methods, fish species and trip notes
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.
Wading, bank fishing or floating?
Access choicesNo single best option
Wading and Bank fishing have the same top score. Use current access, footing, weather, and local rules to choose.
Wading92/100
Wading is in play only where your chosen access has clear footing, legal entry, and no forced crossings.
Bank fishing92/100
Bank and edge fishing remains a practical low-commitment option if access is legal and footing is safe.
FloatingNot recommended
This report does not recommend floating this reach.
Full river report
Is Upper Lost River Drainage worth the trip today? Check flow, weather, hatches, access, and rules for Idaho before you go.
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.
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
FlowHelps
USGS shows 95 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, 116 readings) show a typical middle range of 85 cfs to 169 cfs. Flow is within the typical range for this date, so weather, temperature, and access become the next checks.
SeasonHelps
Fall: Cooler weather, lower crowds, and BWOs can make strong windows before snow.
WeatherHelps
The current NWS air forecast is about 53F, and the next 24-hour high reaches about 71F. Mostly Clear.
Public alertsHelps
No active NWS alert was returned for this forecast point.
Fishing usefulnessHelps
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.
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.
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.
Before you go
IDFG lists Big Lost River and smaller stream rules, including seasonal catch-and-release language and whitefish rules. Check the exact water before fishing.
Where to access the river
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.
Sources and report details
Official agencies and primary river operators come first. Secondary tools are labeled so you know what carries the most weight.
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.
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.
Quick questions
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.