San Marcos HUC8 12100203
A 3,520 km² sub-basin of the Texas-Gulf region in TX. 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
49
Stressed
Drought index
267
Severe
Area in D2+
79.93%
0% exceptional (D4)
Gauges below normal
73%
of 11 reporting
Median flow
53%
p15 of record
Water assets
1,575
134 springs · 621 wells
USGS gauges (13)
- Blanco Rv at Wimberley, TX081710007 cfsp7 · much below normal
- Jacobs Well Spg nr Wimberley, TX081709900 cfsp10 · below normal
- Blanco Rv nr Kyle, TX081713000 cfsp10 · below normal
- Blanco Rv at San Marcos, TX081713500 cfsp10 · below normal
- San Marcos Rv at Luling, TX0817200087 cfsp12 · below normal
- San Marcos Rv at San Marcos, TX0817050094 cfsp15 · below normal
- Blanco Rv at Halifax Rch nr Kyle, TX081712905 cfsp23 · below normal
- San Marcos Rv nr Martindale, TX08171400100 cfsp24 · below normal
- Blanco Rv at Fischer Store Rd nr Fischer, TX0817095013 cfsp38 · normal
- Plum Ck nr Luling, TX081730007 cfsp43 · normal
- Plum Ck at Lockhart, TX081724006 cfsp80 · above normal
- Little Blanco Rv at FM 32 nr Fischer, TX081708900 cfsno long-term record
- Blanco Rv at Valley View Rd nr Fischer, TX081709050 cfsno long-term record
Recent conditions
| Date | DSCI | D2+ % | Gauges low | Flow pct |
|---|---|---|---|---|
| 2026-10-19 | 267 | 79.93 | 8/11 | p15 |
| 2026-10-18 | 267 | 79.93 | 7/11 | p14 |
| 2026-10-17 | 267 | 79.93 | 5/11 | p25 |
| 2026-10-16 | 267 | 79.93 | 6/11 | p15 |
| 2026-10-15 | 267 | 79.93 | 7/11 | p14 |
| 2026-10-14 | 267 | 79.93 | 7/11 | p12 |
| 2026-10-13 | 267 | 79.93 | 6/11 | p14 |
| 2026-10-12 | 267 | 79.93 | 6/11 | p13 |
| 2026-10-11 | 267 | 79.93 | 6/11 | p11 |
| 2026-10-10 | 267 | 79.93 | 7/11 | p11 |
| 2026-10-09 | 267 | 79.93 | 6/11 | p13 |
| 2026-10-08 | 280 | 80.42 | 6/11 | p12 |
| 2026-10-07 | 280 | 80.42 | 5/11 | p25 |
| 2026-10-06 | 280 | 80.42 | 5/11 | p27 |
Top water assets
- 74Trinity Aquifer — Hill Country Regionaquifer
- 66Lower Plum Creek Ws Scs Site 29 Damreservoir
- 66York Creek Ws Scs Site 4 Damreservoir
- 66York Creek Ws Scs Site 5 Damreservoir
- 66Pierce Lake Damreservoir
- 66Plum Creek Ws Scs Site 20 Damreservoir
- 66Plum Creek Ws Scs Site 21 Damreservoir
- 66York Creek Ws Scs Site 3 Damreservoir
- 66Lower Plum Creek Ws Scs Site 23 Damreservoir
- 66Plum Creek Ws Scs Site 16 Damreservoir