| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11012 | 5438 | (49.38%) | 79 | (0.72%) |
| Guadiana | 9261 | 4889 | (52.79%) | 8 | (0.09%) |
| Guadalquivir | 8118 | 4206 | (51.81%) | 28 | (0.34%) |
| Ebro | 7642 | 5299 | (69.34%) | 164 | (2.15%) |
| Duero | 7507 | 3859 | (51.40%) | 33 | (0.44%) |
| Júcar | 3337 | 1032 | (30.93%) | 18 | (0.54%) |
| Miño-Sil | 3030 | 1466 | (48.38%) | 83 | (2.74%) |
| Guadalete-Barbate | 1651 | 1060 | (64.20%) | 32 | (1.94%) |
| Med. Andaluza | 1174 | 732 | (62.35%) | 2 | (0.17%) |
| Segura | 1140 | 236 | (20.70%) | 7 | (0.61%) |
| Galicia Costa | 684 | 452 | (66.08%) | 93 | (13.60%) |
| Cataluña Interna | 677 | 614 | (90.69%) | -2 | (-0.30%) |
| Cantabrico Occidental | 518 | 363 | (70.08%) | 29 | (5.60%) |
| Tinto, Odiel y Piedras | 229 | 169 | (73.80%) | 1 | (0.44%) |
| Cantabrico Oriental | 73 | 52 | (71.23%) | 0 | (0.00%) |
| Pais Vasco Interna | 21 | 16 | (76.19%) | 1 | (4.76%) |
