| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 9102 | (82.33%) | -28 | (-0.25%) |
| Guadiana | 9538 | 6635 | (69.56%) | 104 | (1.09%) |
| Guadalquivir | 8028 | 4838 | (60.26%) | 3 | (0.04%) |
| Ebro | 7802 | 6642 | (85.13%) | -49 | (-0.63%) |
| Duero | 7602 | 6612 | (86.97%) | 71 | (0.93%) |
| Miño-Sil | 3030 | 2366 | (78.09%) | 12 | (0.40%) |
| Júcar | 2846 | 1771 | (62.23%) | 15 | (0.53%) |
| Guadalete-Barbate | 1651 | 906 | (54.88%) | 4 | (0.24%) |
| Med. Andaluza | 1174 | 633 | (53.92%) | 1 | (0.09%) |
| Segura | 1140 | 328 | (28.77%) | 5 | (0.44%) |
| Galicia Costa | 684 | 519 | (75.88%) | -6 | (-0.88%) |
| Cataluña Interna | 677 | 445 | (65.73%) | 10 | (1.48%) |
| Cantábrico Occidental | 490 | 388 | (79.18%) | -7 | (-1.43%) |
| Tinto, Odiel y Piedras | 229 | 210 | (91.70%) | -3 | (-1.31%) |
| Cantábrico Oriental | 73 | 63 | (86.30%) | -1 | (-1.37%) |
| País Vasco Interna | 21 | 20 | (95.24%) | 0 | (0.00%) |
