| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 4599 | (41.60%) | 34 | (0.31%) |
| Guadiana | 9261 | 2677 | (28.91%) | -10 | (-0.11%) |
| Guadalquivir | 8113 | 2216 | (27.31%) | -20 | (-0.25%) |
| Ebro | 7919 | 4151 | (52.41%) | -69 | (-0.87%) |
| Duero | 7507 | 3377 | (44.98%) | -72 | (-0.96%) |
| Miño-Sil | 3030 | 1336 | (44.09%) | -19 | (-0.63%) |
| Júcar | 2846 | 1454 | (51.09%) | -7 | (-0.25%) |
| Guadalete-Barbate | 1651 | 527 | (31.92%) | -3 | (-0.18%) |
| Med. Andaluza | 1174 | 459 | (39.10%) | -8 | (-0.68%) |
| Segura | 1140 | 440 | (38.60%) | -14 | (-1.23%) |
| Galicia Costa | 684 | 391 | (57.16%) | -4 | (-0.58%) |
| Cataluña Interna | 677 | 480 | (70.90%) | -6 | (-0.89%) |
| Cantabrico Occidental | 518 | 322 | (62.16%) | -25 | (-4.83%) |
| Tinto, Odiel y Piedras | 229 | 152 | (66.38%) | 2 | (0.87%) |
| Cantabrico Oriental | 73 | 50 | (68.49%) | -1 | (-1.37%) |
| Pais Vasco Interna | 21 | 15 | (71.43%) | 0 | (0.00%) |
