USGS Streamgage 12301933
Kootenai River below Libby Dam near Libby, MT
Kootenai River below Libby Dam near Libby, MT is USGS streamgage 12301933 in Montana, monitoring river discharge in hydrologic subbasin 17010101. It drains a watershed of about 8,999 square miles. Discharge records at this site go back to 1971. Typical flow runs near 10,092.6 cfs in July and 4,066.7 cfs in April, with the higher of the two arriving in July.
Gauge details
- State
- Montana
- Drainage area
- 8,999 sq mi
- Gauge elevation
- 2,123 ft
- Subbasin (HUC-8)
- 17010101
- Coordinates
- 48.40066, -115.31872
- USGS site number
- 12301933
- Records begin
- 1971-10-01 (55 years)
Typical flow by month
Long-term daily discharge percentiles from the USGS record (up to 55 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 | 3,958.1 | 7,868.1 | 22,712.9 | |
| February | 3,941.4 | 4,352.1 | 19,193.1 | |
| March | 3,536.5 | 4,107.1 | 13,593.5 | |
| April | 3,041.3 | 4,066.7 | 15,170.3 | |
| May | 3,008.4 | 8,075.2 | 20,735.5 | |
| June | 3,362.3 | 14,113.3 | 26,513.3 | |
| July | 3,743.5 | 10,092.6 | 22,545.2 | |
| August | 4,443.9 | 9,226.5 | 17,603.2 | |
| September | 5,406 | 7,998 | 16,066.7 | |
| October | 4,041.3 | 6,025.8 | 20,948.4 | |
| November | 4,164.7 | 13,337.7 | 22,503.3 | |
| December | 4,163.2 | 17,861.9 | 25,238.7 |
All values in cubic feet per second (cfs).