| Cuenca | Capacidad | Embalsada | Variacion | ||
| Tajo | 11056 | 4415 | (39.93%) | -23 | (-0.21%) |
| Guadiana | 9498 | 2173 | (22.88%) | -4 | (-0.04%) |
| Guadalquivir | 8030 | 1499 | (18.67%) | 5 | (0.06%) |
| Ebro | 7963 | 3063 | (38.46%) | 101 | (1.27%) |
| Duero | 7507 | 2645 | (35.23%) | -86 | (-1.15%) |
| Miño-Sil | 3030 | 1657 | (54.69%) | 50 | (1.65%) |
| Júcar | 2846 | 1495 | (52.53%) | 2 | (0.07%) |
| Guadalete-Barbate | 1651 | 349 | (21.14%) | -2 | (-0.12%) |
| Med. Andaluza | 1174 | 390 | (33.22%) | -4 | (-0.34%) |
| Segura | 1140 | 370 | (32.46%) | -1 | (-0.09%) |
| Galicia Costa | 684 | 486 | (71.05%) | -4 | (-0.58%) |
| Cataluña Interna | 677 | 221 | (32.64%) | -5 | (-0.74%) |
| Cantabrico Occidental | 490 | 278 | (56.73%) | -19 | (-3.88%) |
| Tinto, Odiel y Piedras | 229 | 149 | (65.07%) | 1 | (0.44%) |
| Cantabrico Oriental | 73 | 53 | (72.60%) | 4 | (5.48%) |
| Pais Vasco Interna | 21 | 13 | (61.90%) | 0 | (0.00%) |
