| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 6004 | (54.31%) | 55 | (0.50%) |
| Guadiana | 9538 | 3941 | (41.32%) | 7 | (0.07%) |
| Guadalquivir | 8028 | 2830 | (35.25%) | 8 | (0.10%) |
| Ebro | 7802 | 5909 | (75.73%) | -14 | (-0.18%) |
| Duero | 7600 | 5032 | (66.21%) | 174 | (2.29%) |
| Miño-Sil | 3030 | 1834 | (60.53%) | 210 | (6.93%) |
| Júcar | 2846 | 1421 | (49.93%) | 1 | (0.04%) |
| Guadalete-Barbate | 1651 | 472 | (28.59%) | 5 | (0.30%) |
| Med. Andaluza | 1174 | 340 | (28.96%) | 0 | (0.00%) |
| Segura | 1140 | 240 | (21.05%) | -4 | (-0.35%) |
| Galicia Costa | 684 | 598 | (87.43%) | 35 | (5.12%) |
| Cataluña Interna | 677 | 224 | (33.09%) | -2 | (-0.30%) |
| Cantábrico Occidental | 490 | 352 | (71.84%) | 37 | (7.55%) |
| Tinto, Odiel y Piedras | 229 | 188 | (82.10%) | 0 | (0.00%) |
| Cantábrico Oriental | 73 | 60 | (82.19%) | -1 | (-1.37%) |
| País Vasco Interna | 21 | 21 | (100.00%) | 1 | (4.76%) |
