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 2026-10-13); streamflow classes place each USGS gauge's latest reading against its own day-of-year record.
Health score
62
Moderate
Drought index
200
Severe
Area in D2+
0%
0% exceptional (D4)
Gauges below normal
33%
of 3 reporting
Median flow
96%
p49 of record
Water assets
2,268
24 springs · 709 wells
USGS gauges (3)
- HORSEHEAD CREEK AT OELRICHS, SD064008750 cfsp10 · below normal
- CHEYENNE RIVER AT EDGEMONT, SD063950009 cfsp49 · normal
- CHEYENNE RIVER NEAR SPENCER, WY063865002 cfsp89 · above normal
Recent conditions
| Date | DSCI | D2+ % | Gauges low | Flow pct |
|---|---|---|---|---|
| 2026-10-20 | 200 | 0 | 1/3 | p49 |
| 2026-10-19 | 200 | 0 | 1/3 | p48 |
| 2026-10-18 | 200 | 0 | 1/3 | p51 |
| 2026-10-17 | 200 | 0 | 1/3 | p51 |
| 2026-10-16 | 200 | 0 | 1/3 | p51 |
| 2026-10-15 | 200 | 0 | 1/3 | p55 |
| 2026-10-14 | 200 | 0 | 1/3 | p52 |
| 2026-10-13 | 200 | 0 | 1/3 | p32 |
| 2026-10-12 | 200 | 0 | 1/3 | p32 |
| 2026-10-11 | 200 | 0 | 1/3 | p36 |
| 2026-10-10 | 200 | 0 | 1/3 | p36 |
| 2026-10-09 | 200 | 0 | 1/3 | p38 |
| 2026-10-08 | 200 | 0 | 1/3 | p40 |
| 2026-10-07 | 200 | 0 | 0/1 | p79 |
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