| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 5596 | (50.62%) | 36 | (0.33%) |
| Guadiana | 9261 | 3763 | (40.63%) | -14 | (-0.15%) |
| Guadalquivir | 8113 | 3700 | (45.61%) | 12 | (0.15%) |
| Ebro | 7642 | 5851 | (76.56%) | -101 | (-1.32%) |
| Duero | 7507 | 5393 | (71.84%) | -59 | (-0.79%) |
| Miño-Sil | 3030 | 2374 | (78.35%) | -10 | (-0.33%) |
| Júcar | 2846 | 1192 | (41.88%) | 24 | (0.84%) |
| Guadalete-Barbate | 1651 | 821 | (49.73%) | 0 | (0.00%) |
| Med. Andaluza | 1174 | 586 | (49.91%) | 0 | (0.00%) |
| Segura | 1140 | 407 | (35.70%) | 4 | (0.35%) |
| Galicia Costa | 684 | 576 | (84.21%) | 25 | (3.65%) |
| Cataluña Interna | 677 | 497 | (73.41%) | 1 | (0.15%) |
| Cantabrico Occidental | 518 | 373 | (72.01%) | -12 | (-2.32%) |
| Tinto, Odiel y Piedras | 229 | 174 | (75.98%) | -2 | (-0.87%) |
| Cantabrico Oriental | 73 | 62 | (84.93%) | 0 | (0.00%) |
| Pais Vasco Interna | 21 | 19 | (90.48%) | 0 | (0.00%) |
