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Lower San Joaquin River HUC8 18040002

A 2,377 km² sub-basin of the California region in CA. 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
65
Moderate
Drought index
7
Abnormally dry
Area in D2+
0%
0% exceptional (D4)
Gauges below normal
75%
of 4 reporting
Median flow
49%
p10 of record
Water assets
1,274
1 springs · 1,260 wells

USGS gauges (4)

Recent conditions

DateDSCID2+ %Gauges lowFlow pct
2026-10-20703/4p10
2026-10-19703/4p14
2026-10-18703/4p14
2026-10-17703/4p15
2026-10-16703/4p15
2026-10-15703/4p15
2026-10-14703/4p15
2026-10-13703/4p16
2026-10-12703/4p16
2026-10-11703/4p16
2026-10-10703/4p16
2026-10-09703/4p16
2026-10-08704/4p17
2026-10-07704/4p16

Top water assets