| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 8919 | (80.67%) | 46 | (0.42%) |
| Guadiana | 9538 | 4925 | (51.63%) | 46 | (0.48%) |
| Guadalquivir | 8028 | 3756 | (46.79%) | 50 | (0.62%) |
| Ebro | 7802 | 5870 | (75.23%) | 35 | (0.45%) |
| Duero | 7600 | 7010 | (92.23%) | 95 | (1.25%) |
| Miño-Sil | 3030 | 2649 | (87.43%) | 4 | (0.13%) |
| Júcar | 2846 | 1611 | (56.61%) | 12 | (0.42%) |
| Guadalete-Barbate | 1651 | 504 | (30.53%) | 11 | (0.67%) |
| Med. Andaluza | 1174 | 358 | (30.49%) | 13 | (1.11%) |
| Segura | 1140 | 279 | (24.47%) | 2 | (0.18%) |
| Galicia Costa | 684 | 604 | (88.30%) | -4 | (-0.58%) |
| Cataluña Interna | 677 | 122 | (18.02%) | 3 | (0.44%) |
| Cantabrico Occidental | 490 | 439 | (89.59%) | 10 | (2.04%) |
| Tinto, Odiel y Piedras | 229 | 195 | (85.15%) | 0 | (0.00%) |
| Cantabrico Oriental | 73 | 65 | (89.04%) | -2 | (-2.74%) |
| Pais Vasco Interna | 21 | 19 | (90.48%) | 0 | (0.00%) |
