Bitterroot River
The best month to fish the Bitterroot River is September. The month to avoid is April. Right now, in September, it is worth going.
- January: 71 out of 100
- February: 71 out of 100
- March: 72 out of 100
- April: 50 out of 100
- May: 58 out of 100
- June: 55 out of 100
- July: 71 out of 100
- August: 71 out of 100
- September: 94 out of 100
- October: 82 out of 100
- November: 71 out of 100
- December: 71 out of 100
GAUGE 12352500 · COLOURED BY SEPTEMBER
Month by month
| MONTH | TYPICAL FLOW | RANGE (P20–P80) | WATER | AIR HIGH | RAIN | SCORE |
|---|---|---|---|---|---|---|
| January | 779 cfs | 688–992 | — | — | — | 71 |
| February | 830 cfs | 755–1,006 | — | — | — | 71 |
| March | 1,075 cfs | 882–1,728 | 42.9°F | — | — | 72 |
| April | 2,531 cfs | 1,795–3,515 | 47.3°F | — | — | 50 |
| May | 7,178 cfs | 5,536–8,859 | 50.9°F | — | — | 58 |
| June | 7,237 cfs | 4,665–10,340 | 57.8°F | — | — | 55 |
| July | 1,705 cfs | 1,060–2,898 | 67.0°F | — | — | 71 |
| August | 677 cfs | 595–852 | 65.7°F | — | — | 71 |
| SeptemberNOW | 717 cfs | 607–812 | 59.2°F | — | — | 94 |
| October | 881 cfs | 723–1,067 | 49.7°F | — | — | 82 |
| November | 1,127 cfs | 928–1,633 | 39.7°F | — | — | 71 |
| December | 925 cfs | 786–1,206 | — | — | — | 71 |
WHERE THESE NUMBERS COME FROM
Flow and water temperature are medians of the monthly means reported by USGS gauge 12352500 over 2005-2024. Air temperature and precipitation are ten-year normals from Open-Meteo at this river’s gauge coordinates.
The window is deliberate. USGS’s own full-record statistics for a dammed river reach back before the dam — at Lees Ferry, to 1922, forty-one years before Glen Canyon closed — and describe a river that no longer exists.
Flow is scored against this river’s own fishable band of 830–1,705 cfs. There is no universal band: 8,000 cfs is low water on a big tailwater and a flood on a spring creek.
Water temperature is a ceiling rather than a weight. Above about 68°F a trout that is fought and released frequently dies anyway, so no month above that line is scored as worth booking, however good its flow.
Regulations, licences and access change without notice and are not reproduced here as fact — check the state agency before you travel. A median describes twenty years; it does not forecast your week. Source: U.S. Geological Survey, National Water Information System.