| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 8712 | (78.80%) | -217 | (-1.96%) |
| Guadiana | 9538 | 6340 | (66.47%) | -81 | (-0.85%) |
| Guadalquivir | 8028 | 4403 | (54.85%) | -96 | (-1.20%) |
| Ebro | 7802 | 6403 | (82.06%) | -229 | (-2.93%) |
| Duero | 7602 | 6360 | (83.66%) | -225 | (-2.96%) |
| Miño-Sil | 3030 | 2475 | (81.68%) | -57 | (-1.88%) |
| Júcar | 2846 | 1702 | (59.80%) | -26 | (-0.91%) |
| Guadalete-Barbate | 1651 | 833 | (50.45%) | -15 | (-0.91%) |
| Med. Andaluza | 1174 | 642 | (54.68%) | -10 | (-0.85%) |
| Segura | 1140 | 344 | (30.18%) | -5 | (-0.44%) |
| Galicia Costa | 684 | 437 | (63.89%) | -24 | (-3.51%) |
| Cataluña Interna | 677 | 530 | (78.29%) | -13 | (-1.92%) |
| Cantábrico Occidental | 490 | 400 | (81.63%) | -14 | (-2.86%) |
| Tinto, Odiel y Piedras | 229 | 197 | (86.03%) | 0 | (0.00%) |
| Cantábrico Oriental | 73 | 59 | (80.82%) | -1 | (-1.37%) |
| País Vasco Interna | 21 | 19 | (90.48%) | 0 | (0.00%) |
