| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 3881 | (35.10%) | 30 | (0.27%) |
| Guadiana | 9261 | 3475 | (37.52%) | -10 | (-0.11%) |
| Guadalquivir | 8113 | 2800 | (34.51%) | 13 | (0.16%) |
| Ebro | 7642 | 4455 | (58.30%) | 458 | (5.99%) |
| Duero | 7507 | 3374 | (44.94%) | 165 | (2.20%) |
| Miño-Sil | 3030 | 2042 | (67.39%) | 206 | (6.80%) |
| Júcar | 2846 | 1001 | (35.17%) | 0 | (0.00%) |
| Guadalete-Barbate | 1651 | 741 | (44.88%) | -3 | (-0.18%) |
| Med. Andaluza | 1174 | 562 | (47.87%) | -7 | (-0.60%) |
| Segura | 1140 | 296 | (25.96%) | -3 | (-0.26%) |
| Galicia Costa | 684 | 588 | (85.96%) | 74 | (10.82%) |
| Cataluña Interna | 677 | 394 | (58.20%) | -3 | (-0.44%) |
| Cantabrico Occidental | 518 | 420 | (81.08%) | 81 | (15.64%) |
| Tinto, Odiel y Piedras | 229 | 143 | (62.45%) | 1 | (0.44%) |
| Cantabrico Oriental | 73 | 61 | (83.56%) | 4 | (5.48%) |
| Pais Vasco Interna | 21 | 18 | (85.71%) | 2 | (9.52%) |
