| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 9381 | (84.85%) | 75 | (0.68%) |
| Guadiana | 9538 | 6722 | (70.47%) | 17 | (0.18%) |
| Guadalquivir | 8028 | 4900 | (61.04%) | 23 | (0.29%) |
| Ebro | 7802 | 6895 | (88.37%) | 142 | (1.82%) |
| Duero | 7602 | 6886 | (90.58%) | 95 | (1.25%) |
| Miño-Sil | 3030 | 2566 | (84.69%) | 75 | (2.48%) |
| Júcar | 2846 | 1803 | (63.35%) | 14 | (0.49%) |
| Guadalete-Barbate | 1651 | 914 | (55.36%) | 3 | (0.18%) |
| Med. Andaluza | 1174 | 657 | (55.96%) | 5 | (0.43%) |
| Segura | 1140 | 336 | (29.47%) | 2 | (0.18%) |
| Galicia Costa | 684 | 576 | (84.21%) | 0 | (0.00%) |
| Cataluña Interna | 677 | 477 | (70.46%) | 17 | (2.51%) |
| Cantábrico Occidental | 490 | 427 | (87.14%) | 18 | (3.67%) |
| Tinto, Odiel y Piedras | 229 | 210 | (91.70%) | -1 | (-0.44%) |
| Cantábrico Oriental | 73 | 64 | (87.67%) | 2 | (2.74%) |
| País Vasco Interna | 21 | 21 | (100.00%) | 1 | (4.76%) |
