Upper Musselshell HUC8 10040201
A 10,400 km² sub-basin of the Missouri region in MT. Drought coverage is from the US Drought Monitor (map of 2026-09-01); streamflow classes place each USGS gauge's latest reading against its own day-of-year record.
Health score
61
Moderate
Drought index
282
Severe
Area in D2+
82.02%
0% exceptional (D4)
Gauges below normal
25%
of 4 reporting
Median flow
50%
p28 of record
Water assets
1,590
41 springs · 317 wells
USGS gauges (4)
- Musselshell River ab Mud Cr nr Shawmut MT061230306 cfsp17 · below normal
- Musselshell River nr Martinsdale, MT061196009 cfsp26 · normal
- Musselshell River at Harlowton MT0612050026 cfsp31 · normal
- Musselshell River ab Big Coulee Creek at Lavina MT0612560052 cfsp31 · normal
Recent conditions
| Date | DSCI | D2+ % | Gauges low | Flow pct |
|---|---|---|---|---|
| 2026-09-07 | 282 | 82.02 | 1/4 | p28 |
Top water assets
- 69American Forkriver
- 69Bonanza Creekriver
- 69Miller Creekriver
- 69Niel Creekriver
- 69Little Careless Creekriver
- 69Careless Creekriver
- 69Flagstaff Creekriver
- 69Careless Creekriver
- 69East Fork Blake Creekriver
- 69Alabaugh Creekriver