Upper Merced HUC8 18040008
A 3,288 km² sub-basin of the California region in CA. 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
79
Healthy
Drought index
93
Abnormally dry
Area in D2+
0%
0% exceptional (D4)
Gauges below normal
0%
of 2 reporting
Median flow
69%
p32 of record
Water assets
1,883
15 springs · 458 wells
USGS gauges (2)
- MERCED R A POHONO BRIDGE NR YOSEMITE CA1126650027 cfsp30 · normal
- MERCED R A HAPPY ISLES BRIDGE NR YOSEMITE CA1126450014 cfsp35 · normal
Recent conditions
| Date | DSCI | D2+ % | Gauges low | Flow pct |
|---|---|---|---|---|
| 2026-09-07 | 93 | 0 | 0/2 | p32 |
Top water assets
- 69Merced Riverriver
- 69Crane Creekriver
- 69Crane Creekriver
- 69Ottoway Creekriver
- 69Clark Fork Illilouette Creekriver
- 69Triple Peak Forkriver
- 69Big Creekriver
- 69Long Meadow Creekriver
- 69Illilouette Creekriver
- 69Moss Creekriver