About this river
Flathead River is a 19.1 mile river near Go Sail Flathead Lake in Montana. Streamflow is measured at the USGS gauge Flathead River near Polson MT (site 12372000). The National Hydrography Dataset places it at stream order 7. Reach geometry comes from the USGS National Hydrography Dataset.
Typical flow by month
1939 to 2026
Flathead River typically runs highest in June, at a median 24,700 cfs, and lowest in September, at 5,615 cfs. The highest flow on record for any single day is 72,700 cfs, in 1948.
| Month | Typical (cfs) | Usual range (cfs) | Relative level |
|---|---|---|---|
| January | 9,960 | 8,140 to 12,000 | |
| February | 8,970 | 6,900 to 11,900 | |
| March | 7,780 | 5,720 to 10,200 | |
| April | 8,790 | 6,270 to 13,500 | |
| May | 18,500 | 12,600 to 25,300 | |
| June | 24,700 | 15,600 to 36,150 | |
| July | 12,500 | 9,060 to 16,500 | |
| August | 5,700 | 4,270 to 7,620 | |
| September | 5,615 | 4,255 to 7,620 | |
| October | 7,020 | 4,710 to 9,080 | |
| November | 8,030 | 5,810 to 10,500 | |
| December | 9,760 | 7,720 to 12,100 |
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 87 years of record. Statistics published by the US Geological Survey for Flathead River near Polson MT (site 12372000). Conditions on any given day can fall well outside the usual range. Check the current reading before you go.
Embed this gauge on your site
Paste this snippet anywhere, an outfitter page, a club site, a trip report, to show 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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