| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 6491 | (58.71%) | 6 | (0.05%) |
| Guadiana | 9498 | 3033 | (31.93%) | -6 | (-0.06%) |
| Guadalquivir | 8030 | 1911 | (23.80%) | 0 | (0.00%) |
| Ebro | 7963 | 3869 | (48.58%) | -18 | (-0.23%) |
| Duero | 7507 | 4886 | (65.08%) | -53 | (-0.71%) |
| Miño-Sil | 3030 | 2184 | (72.08%) | -17 | (-0.56%) |
| Júcar | 2846 | 1651 | (58.01%) | 7 | (0.25%) |
| Guadalete-Barbate | 1651 | 417 | (25.26%) | -9 | (-0.55%) |
| Med. Andaluza | 1174 | 403 | (34.33%) | 4 | (0.34%) |
| Segura | 1140 | 399 | (35.00%) | 17 | (1.49%) |
| Galicia Costa | 684 | 552 | (80.70%) | -23 | (-3.36%) |
| Cataluña Interna | 677 | 173 | (25.55%) | 2 | (0.30%) |
| Cantabrico Occidental | 490 | 430 | (87.76%) | 4 | (0.82%) |
| Tinto, Odiel y Piedras | 229 | 158 | (69.00%) | 1 | (0.44%) |
| Cantabrico Oriental | 73 | 66 | (90.41%) | 0 | (0.00%) |
| Pais Vasco Interna | 21 | 17 | (80.95%) | -1 | (-4.76%) |
