USGS Streamgage 13042500
Henrys Fork near Island Park, ID
Henrys Fork near Island Park, ID is USGS streamgage 13042500 in Idaho, monitoring river discharge in hydrologic subbasin 17040202. It sits on the Henrys Fork, alongside 4 other gauges Rivermatics tracks on the same river. It drains a watershed of about 501 square miles. Discharge records at this site go back to 1933. Typical flow runs near 1,140.6 cfs in July and 475.7 cfs in April, with the higher of the two arriving in July. Rivermatics issues a daily machine-learned flow outlook for this gauge, reaching 14 days ahead.
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Gauge details
- State
- Idaho
- Drainage area
- 501 sq mi
- Subbasin (HUC-8)
- 17040202
- Coordinates
- 44.41667, -111.39472
- USGS site number
- 13042500
- Records begin
- 1933-01-07 (93 years)
- Rivermatics forecast
- 14-day flow outlook
14-day flow forecast
Based on observations through for Henrys Fork near Island Park, ID. Each day carries a median estimate and the band the model expects the flow to fall within — not a single number to plan against. Forecasts are re-issued daily; see the live screen for the current outlook.
| Date | Low p10 | Expected p50 | High p90 | Range |
|---|---|---|---|---|
| 1,093 | 1,134 | 1,159 | ||
| 969 | 1,110 | 1,156 | ||
| 860 | 1,088 | 1,161 | ||
| 746 | 1,060 | 1,169 | ||
| 680 | 1,026 | 1,161 | ||
| 621 | 990 | 1,148 | ||
| 542 | 930 | 1,132 | ||
| 515 | 921 | 1,129 | ||
| 434 | 855 | 1,107 | ||
| 415 | 835 | 1,100 | ||
| 410 | 820 | 1,091 | ||
| 373 | 788 | 1,087 | ||
| 344 | 758 | 1,079 | ||
| 333 | 746 | 1,076 |
All values in cubic feet per second (cfs). Estimates only — do not use them for navigation or for any safety, rescue, or emergency decision.
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 93 years of data), averaged within each month. These describe the historical normal range — they are not a forecast and not today's reading.
| Month | Low p10 | Typical p50 | High p90 | Range |
|---|---|---|---|---|
| January | 8.7 | 289.9 | 579.1 | |
| February | 13.6 | 323.7 | 580.2 | |
| March | 45.6 | 338.7 | 566.7 | |
| April | 171.7 | 475.7 | 799.6 | |
| May | 450 | 872.8 | 1,602.6 | |
| June | 519.3 | 897.6 | 1,512.7 | |
| July | 657.2 | 1,140.6 | 1,668.4 | |
| August | 644.5 | 1,053.1 | 1,469 | |
| September | 373.4 | 661.7 | 1,041.5 | |
| October | 112.3 | 398.4 | 642.3 | |
| November | 43.1 | 251.1 | 622.8 | |
| December | 7.7 | 287.7 | 576.5 |
All values in cubic feet per second (cfs).
Common questions
- When does Henrys Fork near Island Park, ID normally run highest?
- July, on the long-term record. The median daily flow that month is about 1,140.6 cfs, against 251.1 cfs in November, the lowest month. These are historical normals for the date, not a forecast and not today's reading.
- What is a normal flow for Henrys Fork near Island Park, ID?
- It depends on the month. In January, half of days historically fall near 289.9 cfs, with the middle 80% of days between 8.7 and 579.1 cfs. The month-by-month table on this page gives the full range.
- How long has Henrys Fork near Island Park, ID been measured?
- Discharge records at USGS site 13042500 begin in 1933, about 93 years, covering roughly 9,200 days of published daily values. The long record is what makes the monthly percentiles on this page meaningful.
- Is there a flow forecast for Henrys Fork near Island Park, ID?
- Yes. Rivermatics trains a machine-learned model — a temporal-fusion transformer — on this basin's observed flows, weather, and snowpack, and issues a daily flow outlook reaching 14 days ahead: a median estimate inside a confidence band, not a single number to bet on. Every forecast is scored against days the model never trained on, and that track record is published on the live gauge screen. Open live conditions to see the current outlook.
- Where is Henrys Fork near Island Park, ID?
- The gauge sits at 44.41667, -111.39472, in Idaho, in hydrologic subbasin 17040202, draining roughly 501 square miles.
- Can I use Henrys Fork near Island Park, ID data for flood or safety decisions?
- No. Rivermatics provides estimates, not guarantees, and the readings and forecasts here may be delayed, inaccurate, or wrong. Do not use them for navigation or for any safety, rescue, or emergency decision. Check the National Weather Service and USGS directly, and use your own judgment.
Upstream and downstream on the Henrys Fork
Every gauge Rivermatics tracks on this river, ordered by drainage area — upstream first. See the Henrys Fork in full.
- Henrys Fork near Lake, ID 95 sq mi
- Henrys Fork near Island Park, ID this page
- Henrys Fork near Ashton, ID 1,097 sq mi
- Henrys Fork at St Anthony, ID 1,770 sq mi
- Henrys Fork near Rexburg, ID 2,920 sq mi