| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 5545 | (50.15%) | -171 | (-1.55%) |
| Guadiana | 9261 | 3113 | (33.61%) | 19 | (0.21%) |
| Guadalquivir | 8113 | 2737 | (33.74%) | 76 | (0.94%) |
| Ebro | 7919 | 5575 | (70.40%) | -28 | (-0.35%) |
| Duero | 7507 | 4840 | (64.47%) | 0 | (0.00%) |
| Miño-Sil | 3030 | 1915 | (63.20%) | -97 | (-3.20%) |
| Júcar | 2846 | 1462 | (51.37%) | 23 | (0.81%) |
| Guadalete-Barbate | 1651 | 638 | (38.64%) | 15 | (0.91%) |
| Med. Andaluza | 1174 | 526 | (44.80%) | 36 | (3.07%) |
| Segura | 1140 | 405 | (35.53%) | 0 | (0.00%) |
| Galicia Costa | 684 | 582 | (85.09%) | -23 | (-3.36%) |
| Cataluña Interna | 677 | 582 | (85.97%) | -1 | (-0.15%) |
| Cantabrico Occidental | 518 | 320 | (61.78%) | -44 | (-8.49%) |
| Tinto, Odiel y Piedras | 229 | 171 | (74.67%) | -1 | (-0.44%) |
| Cantabrico Oriental | 73 | 64 | (87.67%) | -2 | (-2.74%) |
| Pais Vasco Interna | 21 | 20 | (95.24%) | 1 | (4.76%) |
