About this river
South Fork Flathead River is a 13.5 mile river near Old Faithful Watersports in Montana. Streamflow is measured at the USGS gauge S F Flathead R ab Twin C nr Hungry Horse MT (site 12359800). The National Hydrography Dataset places it at stream order 6. Reach geometry comes from the USGS National Hydrography Dataset.
Typical flow by month
1965 to 2026
South Fork Flathead River typically runs highest in May, at a median 7,970 cfs, and lowest in February, at 373 cfs. The highest flow on record for any single day is 29,500 cfs, in 1974.
| Month | Typical (cfs) | Usual range (cfs) | Relative level |
|---|---|---|---|
| January | 377 | 260 to 565 | |
| February | 373 | 284 to 574 | |
| March | 448 | 348 to 665 | |
| April | 1,875 | 1,330 to 3,125 | |
| May | 7,970 | 5,020 to 10,700 | |
| June | 6,980 | 4,685 to 9,885 | |
| July | 1,960 | 1,200 to 2,950 | |
| August | 613 | 482 to 830 | |
| September | 414 | 335 to 539 | |
| October | 409 | 316 to 579 | |
| November | 486 | 362 to 745 | |
| December | 404 | 293 to 568 |
Typical is the median of each month’s daily median values, and the usual range runs from the median 25th to the median 75th percentile, across about 52 years of record. Statistics published by the US Geological Survey for S F Flathead R ab Twin C nr Hungry Horse MT (site 12359800). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
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Paste this snippet anywhere, an outfitter page, a club site, a trip report, to show South Fork Flathead River's live streamflow, water level and 7-day trend. It reads the USGS gauge directly, updates itself, and links back here.
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