South Fork Snake River at Irwin
Idaho · Fishing & wading
Measured at USGS 13032500 — SNAKE RIVER NR IRWIN ID · NWS forecast point PALI1
Reading taken Jul 28, 11:30 PM UTC
About normal for the date
At 12,000 CFS, this gauge is running 104% of normal for late July — close to the 11,500 CFS median USGS has recorded for this date across 80 years of record (1935–2026). The stage is 2.3 ft below the NWS action stage of 11.0 ft.
Data-derived guidance from USGS and NWS published values — not official advice, and not a safety assessment.
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Flood stages at Irwin
Official National Weather Service categories for gauge PALI1, issued by WFO PIH. Impact statements are the NWS's own wording for this location, reproduced verbatim.
-
Action 11.0 ft · 20,688 CFS
- 11.0 ft Fields aand low-lying areas near the river from Palisades Dam downstream to near Table Rock Canyon area may experience seep and ponding.
- Right now 8.73 ft
NWS forecast: 8.65 ft by Jul 29, 6:00 AM UTC.
12 months of flow at Irwin
Daily values from USGS gauge 13032500. Provisional data, subject to revision.
Highest crests on record at Irwin
| Stage | Flow | Date |
|---|---|---|
| 15.25 ft | 41,800 CFS | Jun 20, 1997 |
| 15.01 ft | 40,400 CFS | Jun 19, 1997 |
| 13.31 ft | 31,800 CFS | Jun 4, 1956 |
| 13.18 ft | 31,200 CFS | Jun 28, 1954 |
| 12.69 ft | 28,800 CFS | May 29, 1951 |
| 12.52 ft | 27,800 CFS | Jul 3, 1950 |
| 12.26 ft | 25,400 CFS | Jun 25, 1974 |
| 11.91 ft | 24,500 CFS | Jun 13, 2017 |
| 11.90 ft | 24,200 CFS | Jul 15, 2011 |
| 11.78 ft | 23,800 CFS | Jun 29, 2009 |
Historical crests published by the National Weather Service for this gauge.
About South Fork Snake River at Irwin
This gauge measures South Fork Snake River at Irwin, Idaho — the reading paddlers, anglers and outfitters on this stretch check before committing to a shuttle.
Below Palisades Dam; Idaho's premier float-fishing river.
Raw CFS means little on its own, so every reading on this page is shown against the USGS median for the same calendar day — 11,500 CFS for late July, from 80 years of record.
Because the National Weather Service also operates a forecast point here, the page carries the official flood-category ladder and the NWS's own stage-by-stage impact statements.
South Fork Snake River at Irwin — common questions
What is the current flow on South Fork Snake River at Irwin?
As of the last reading on this page, South Fork Snake River at Irwin was running 12,000 CFS at a gage height of 8.73 ft, or 104% of the USGS median for this date. The number updates automatically from USGS gauge 13032500, which reports every 15 to 60 minutes.
Is that high or low for this time of year?
The USGS median flow for late July at this gauge is 11,500 CFS, calculated from 80 years of record (1935–2026). Comparing today's reading against that median is the only way a raw CFS number tells you anything — 200 CFS is a drought on one river and a flood on another.
How often does this reading update?
USGS transmits from this gauge every 15 to 60 minutes. This page bakes in the most recent reading when it is rebuilt, then refreshes live from USGS when you open it. Readings are provisional and subject to revision by USGS.
Is South Fork Snake River at Irwin wadeable right now?
That depends on the reach and on your own judgement — riverlvl will not tell you the water is safe to stand in. What it will tell you is whether today's flow is unusually high or low for the date, against a seasonal median of 11,500 CFS, which is the single most useful input to that decision.
What makes the flow change on this stretch?
Rain in the basin upstream, plus seasonal baseflow. The 12-month chart shows the past year of daily values, which is the clearest picture of how this gauge behaves through the seasons.
Where does this data come from?
Flow and gage height are public-domain USGS data from gauge 13032500. Flood categories, impact statements and the forecast come from the NOAA / National Weather Service National Water Prediction Service, gauge PALI1. riverlvl adds the seasonal comparison and plain-English summary; it is not an official source and does not issue warnings.