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 2026-10-13); streamflow classes place each USGS gauge's latest reading against its own day-of-year record.
Health score
55
Moderate
Drought index
153
Moderate
Area in D2+
0%
0% exceptional (D4)
Gauges below normal
100%
of 4 reporting
Median flow
40%
p16 of record
Water assets
1,590
41 springs · 317 wells
USGS gauges (4)
- Musselshell River ab Big Coulee Creek at Lavina MT0612560013 cfsp12 · below normal
- Musselshell River ab Mud Cr nr Shawmut MT061230307 cfsp15 · below normal
- Musselshell River nr Martinsdale, MT0611960023 cfsp18 · below normal
- Musselshell River at Harlowton MT0612050041 cfsp22 · below normal
Recent conditions
| Date | DSCI | D2+ % | Gauges low | Flow pct |
|---|---|---|---|---|
| 2026-10-21 | 153 | 0 | 4/4 | p16 |
| 2026-10-20 | 153 | 0 | 2/4 | p21 |
| 2026-10-19 | 153 | 0 | 2/4 | p29 |
| 2026-10-18 | 153 | 0 | 2/4 | p33 |
| 2026-10-17 | 153 | 0 | 1/4 | p36 |
| 2026-10-16 | 153 | 0 | 1/4 | p37 |
| 2026-10-15 | 172 | 0 | 0/4 | p44 |
| 2026-10-14 | 172 | 0 | 0/4 | p60 |
| 2026-10-13 | 172 | 0 | 0/4 | p63 |
| 2026-10-12 | 172 | 0 | 0/4 | p66 |
| 2026-10-11 | 172 | 0 | 0/4 | p50 |
| 2026-10-10 | 172 | 0 | 0/4 | p40 |
| 2026-10-09 | 172 | 0 | 0/4 | p36 |
| 2026-10-08 | 215 | 15.27 | 0/4 | p34 |
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