| Cuenca | Capacidad | Embalsada | Variación | ||
| Tajo | 11056 | 6071 | (54.91%) | -33 | (-0.30%) |
| Guadiana | 9538 | 3749 | (39.30%) | 1 | (0.01%) |
| Guadalquivir | 8028 | 2427 | (30.23%) | 28 | (0.35%) |
| Ebro | 7802 | 4846 | (62.11%) | 215 | (2.76%) |
| Duero | 7600 | 4811 | (63.30%) | 118 | (1.55%) |
| Miño-Sil | 3030 | 2059 | (67.95%) | 140 | (4.62%) |
| Júcar | 2846 | 1146 | (40.27%) | -10 | (-0.35%) |
| Guadalete-Barbate | 1651 | 340 | (20.59%) | 2 | (0.12%) |
| Med. Andaluza | 1174 | 258 | (21.98%) | -5 | (-0.43%) |
| Segura | 1140 | 172 | (15.09%) | -7 | (-0.61%) |
| Galicia Costa | 684 | 489 | (71.49%) | 101 | (14.77%) |
| Cataluña Interna | 677 | 187 | (27.62%) | -6 | (-0.89%) |
| Cantábrico Occidental | 490 | 377 | (76.94%) | 25 | (5.10%) |
| Tinto, Odiel y Piedras | 229 | 161 | (70.31%) | 0 | (0.00%) |
| Cantábrico Oriental | 73 | 65 | (89.04%) | 0 | (0.00%) |
| País Vasco Interna | 21 | 19 | (90.48%) | 0 | (0.00%) |
