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All Idaho reports
Big Wood River
Photo: U.S. Geological Survey from Reston, VA, USA Opens in a new tab. · Public domain
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 rating74
Rating updatedRiver local time:
Why this recommendation?
USGS shows 56 cfs. The flow has been stable over about 6 hours. USGS marks this reading provisional and may revise it. USGS records for this date (1948-2025, 39 readings) show a median near 73 cfs and the lower quartile near 59 cfs; today's flow is below normal for the date. This is below normal, so edge depth, temperature, and pressure matter.
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 Big Wood near Ketchum RiverReports and USGS gauge first.
- Try
- Confirm the section is open before fishing in spring.
- Leave when
- Skip the Big Wood when the reach is closed, when IDFG special-rule language does not match your plan, when runoff makes crossings unsafe, when low warm water stresses trout, or when the only visible access is private bank.
Flow and weather
Showing server-checked river conditions while current readings refresh.
- Flow
- 56 cfs
- From the latest stored river check. Open the official source for the newest reading.
- Air forecast
- 40°F
- Next 24h high
- 76.0°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
Sunny
- Wind
- 2 mph
- Weather checked
More forecast and source details
Sunny
National Weather Service
Big Wood River Ketchum forecast point
The National Weather Service forecast is temporarily unavailable.
Live data
Where these readings come from
RiverReports gauge: Big Wood River near Ketchum
Flies for this time of year
Seasonal starting points, not a live hatch report. Match what you see on the water.
- Ant PatternsAntView fly guide ↗
- Beetle PatternsbeetleView fly guide ↗
- Grasshopper PatternshopperView fly guide ↗
- Caddis Patterns by Stagesmall caddisView fly guide ↗
- Blue-Winged Olive PatternsBWO dryView fly guide ↗
See flies for every season
SeasonWhat to look forFlies to try
Spring
What to look forBWOs, midges, early caddis
Early summer
What to look forGreen drakes, PMDs, caddis, golden stones
Late summerThis season
What to look forTerrestrials, tricos, caddis
Flies to try
FallThis season
What to look forBWOs, midges, October caddis
Flies to try
Also try October caddis
Each fly name opens its matching Fly Box guide.
More fishing tips
Methods, fish species and trip notes
How to fish Big Wood River today.
The Big Wood is strongest after runoff drops, water stays cool, and reach rules are open. In high water, warm low water, or closed sections, use a legal alternative.
Low clear summer
Use stealth, longer leaders, and smaller dries or droppers.
Good medium flow
Dry-droppers, caddis, PMDs, and nymph rigs can cover riffles and banks.
Runoff
Avoid unsafe wading and wait for clarity to return.
Warm or low water
Fish early, use a thermometer, and stop if trout recovery is poor.
Wading, bank fishing or floating?
Access choicesNo single best option
Wading, Bank fishing, and Floating have the same top score. Use current access, footing, weather, and local rules to choose.
Wading74/100
Wading is in play only where your chosen access has clear footing, legal entry, and no forced crossings.
Bank fishing74/100
Bank and edge fishing remains a practical low-commitment option if access is legal and footing is safe.
Floating74/100
A float is in play where this report supports boat access and wind, releases, and shuttle logistics are manageable.
Full river report
Is Big Wood River worth the trip today? Check flow, weather, hatches, access, and rules for Idaho before you go.
The Big Wood is a classic Sun Valley trout river, but rules vary by reach and season. Use the Ketchum gauge, then confirm open dates, gear rules, and access before fishing.
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.
- Riffle
- A riffle is shallow, fast water broken by rocks.
- 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.
- River reach
- A reach is one named section of a river or stream.
Why this call
Why this score
FlowUse caution
USGS shows 56 cfs. The flow has been stable over about 6 hours. USGS marks this reading provisional and may revise it. USGS records for this date (1948-2025, 39 readings) show a median near 73 cfs and the lower quartile near 59 cfs; today's flow is below normal for the date. This is below normal, so edge depth, temperature, and pressure matter.
SeasonHelps
Fall: Cooler water, BWOs, and streamers make a strong late-season plan.
WeatherHelps
The current NWS air forecast is about 40F, and the next 24-hour high reaches about 76F. Sunny.
Public alertsHelps
No active NWS alert was returned for this forecast point.
Fishing usefulnessHelps
Skip the Big Wood when the reach is closed, when IDFG special-rule language does not match your plan, when runoff makes crossings unsafe, when low warm water stresses trout, or when the only visible access is private bank.
Trip notes
Check these before you choose a reach.
Use the RiverReports Ketchum chart and USGS 13135500 together. Stable or slowly falling post-runoff flows create the easiest fly-fishing window. Runoff, very low warm water, or lower-valley intermittent conditions should push you toward a different reach or another river.
Skip the Big Wood when the reach is closed, when IDFG special-rule language does not match your plan, when runoff makes crossings unsafe, when low warm water stresses trout, or when the only visible access is private bank.
Start with the Ketchum and upper Wood River Valley area, then decide whether Hailey or lower-valley water is actually suitable that day. Match flies to the flow and temperature instead of treating the whole Big Wood as one uniform river.
If the Big Wood is closed, high, warm, or crowded, compare the Big Lost River or Boise River after checking current rules and flows. Smaller stream ideas should be researched separately before fishing.
Big Wood River 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 Wood River rules by reach, including seasonal closures and special catch-and-release/barbless-hook water. Check current Idaho rules before fishing.
Where to access the river
Ketchum and upper valley
The main report focus, using the Big Wood near Ketchum gauge.
Highway 75 reach context
IDFG special rules can apply by milepost and section. Check current language.
Wood River Valley USFS access
Useful upper-valley public-land and campground context.
Hailey and lower valley
Different flow, access, and temperature considerations than Ketchum water.
- IDFG rules vary by reach, season, and gear restrictions.
- Private banks and development are part of valley access planning.
- Runoff can turn a short wade into unsafe water quickly.
- Lower river irrigation effects should be checked before assuming trout conditions.
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.
More helpful links
Use these links for stocking, safety, and other local details.
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.
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.
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.
More helpful links
Use these links for stocking, safety, and other local details.
What this source covers
Open this page for more river information and check when it was last updated.
How this report was checked
How this report was checked
Reviewed byBlueStreamFly River Review Team
Trip guidance checked
What was checked: This Big Wood River report is maintained from RiverReports and USGS flow data, Idaho Fish and Game rule and river-management sources, Forest Service access references, weather checks, and Wood River Valley 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
What Big Wood reach does this page cover?
It focuses on the Ketchum and upper Wood River Valley trout fishery, with lower-valley cautions.
Which gauge should I use?
Use USGS 13135500, Big Wood River near Ketchum, shown with RiverReports and official USGS context.
Are there spring closures?
Some Big Wood sections have seasonal closures or special rules. Check IDFG before fishing.
What makes the Big Wood good in summer?
Post-runoff hatches, clear riffles, and terrestrial banks can be excellent when water remains cool.