Angostura Reservoir HUC8 10120106
A 3,632 km² sub-basin of the Missouri region in NE, SD, WY. 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
47
Stressed
Drought index
397
Extreme
Area in D2+
100%
0% exceptional (D4)
Gauges below normal
50%
of 2 reporting
Median flow
5%
p18 of record
Water assets
2,268
24 springs · 709 wells
USGS gauges (3)
- CHEYENNE RIVER NEAR SPENCER, WY063865000 cfsp10 · below normal
- CHEYENNE RIVER AT EDGEMONT, SD063950000 cfsp27 · normal
- HORSEHEAD CREEK AT OELRICHS, SD064008750 cfsno long-term record
Recent conditions
| Date | DSCI | D2+ % | Gauges low | Flow pct |
|---|---|---|---|---|
| 2026-09-07 | 397 | 100 | 1/2 | p18 |
Top water assets
- 78Oscar P/Laura L Coperiver
- 76Hot Springs Irrigation & Livestock Companyriver
- 76Bernard D Simonswell
- 76Effie Gowwell
- 76Rudolph Lulfriver
- 76George Lebarriver
- 76Weinreis Brothersriver
- 76John & Heidi Mcbrideriver
- 76Tetrad Corporationriver
- 76J.A. Stanleyriver