Caribbean Region HUC 21
The Caribbean Region hydrologic region spans Puerto Rico and is divided into 8 HUC8 sub-basins. Conditions are the US Drought Monitor's weekly area coverage and the day-of-year streamflow percentiles of the USGS gauges inside each sub-basin, as of 2026-09-07.
Health score
61
Moderate
Drought index
270
Severe
Area in D2+
64.6%
2 sub-basins ≥50%
Gauges below normal
61%
of 92 reporting
Water assets
50
avg WIS 58
Sub-basins
8
0 alerts · 0 transfers
quality 58drought 46streamflow 43regulatory 100coverage 84
Sub-basins, driest first
| Sub-basin | Assets | Avg WIS | Drought | Gauges low | Flow pct | Health |
|---|---|---|---|---|---|---|
| Southern Puerto Rico 21010004 · PR | 13 | 60.5 | Extreme (375) | 41% | p50 | 48 |
| Eastern Puerto Rico 21010005 · PR | 11 | 59.5 | Extreme (349) | 77% | p8 | 40 |
| Cibuco-Guajataca 21010002 · PR | 19 | 55.2 | Moderate (154) | 67% | p17 | 56 |
| Culebrinas-Guanajibo 21010003 · PR | 7 | 58.4 | Abnormally dry (94) | 60% | p9 | 61 |
| Puerto Rican Western Islands 21010007 · PR | 0 | — | no data | — | — | — |
| Puerto Rican Eastern Islands 21010008 · PR | 0 | — | no data | — | — | — |
| St. John-St. Thomas 21020001 · VI | 0 | — | no data | — | — | — |
| St. Croix 21020002 · VI | 0 | — | no data | — | — | — |
Top water assets in this region
- 69North Coast Limestone Aquifer — Arecibo RegionCibuco-Guajataca
- 69Caonillas DamCibuco-Guajataca
- 67Dos Bocas DamCibuco-Guajataca
- 67Guayo DamCulebrinas-Guanajibo
- 67Matrullas DamCibuco-Guajataca
- 67Garzas DamCibuco-Guajataca
- 67Guajataca DamCibuco-Guajataca
- 67Guayabal DamSouthern Puerto Rico
- 67Guineo DamCibuco-Guajataca
- 67Toa Vaca DamSouthern Puerto Rico