| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 7677 | (69.44%) | -241 | (-2.18%) |
| Guadiana | 9538 | 4292 | (45.00%) | -75 | (-0.79%) |
| Guadalquivir | 8028 | 3142 | (39.14%) | -80 | (-1.00%) |
| Ebro | 7802 | 5324 | (68.23%) | -192 | (-2.46%) |
| Duero | 7600 | 6212 | (81.73%) | -198 | (-2.61%) |
| Miño-Sil | 3030 | 2515 | (83.00%) | 4 | (0.13%) |
| Júcar | 2846 | 1371 | (48.17%) | -36 | (-1.26%) |
| Guadalete-Barbate | 1651 | 420 | (25.44%) | -11 | (-0.67%) |
| Med. Andaluza | 1174 | 335 | (28.53%) | -8 | (-0.68%) |
| Segura | 1140 | 239 | (20.96%) | -7 | (-0.61%) |
| Galicia Costa | 684 | 482 | (70.47%) | -33 | (-4.82%) |
| Cataluña Interna | 677 | 243 | (35.89%) | -6 | (-0.89%) |
| Cantábrico Occidental | 490 | 441 | (90.00%) | -5 | (-1.02%) |
| Tinto, Odiel y Piedras | 229 | 188 | (82.10%) | -3 | (-1.31%) |
| Cantábrico Oriental | 73 | 60 | (82.19%) | -1 | (-1.37%) |
| País Vasco Interna | 21 | 19 | (90.48%) | 0 | (0.00%) |
