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River basins

Source: MITECO Updated 20 OCT 2026

Cantábrico Occidental

Capacity485 hm³

Stored water271 hm³

Main reservoirs

Salime36.97%Capacity: 238 hm³Doiras73.2%Capacity: 97 hm³Arbón92.68%Capacity: 41 hm³Tanes64.71%Capacity: 34 hm³

Cantábrico Oriental

Capacity73 hm³

Stored water39 hm³

Main reservoirs

Añarbe52.63%Capacity: 38 hm³Ordunte50.0%Capacity: 22 hm³Ibiur62.5%Capacity: 8 hm³San Antón60.0%Capacity: 5 hm³

Cuenca Mediterránea Andaluza

Capacity1,174 hm³

Stored water739 hm³

Main reservoirs

Guadalhorce-Guadalteba88.53%Capacity: 279 hm³Viñuela, La83.64%Capacity: 165 hm³Cuevas de Almanzora9.32%Capacity: 161 hm³Rules81.08%Capacity: 111 hm³

Cuencas Internas de Cataluña

Capacity677 hm³

Stored water494 hm³

Main reservoirs

Susqueda78.97%Capacity: 233 hm³Sau69.09%Capacity: 165 hm³La Baells70.64%Capacity: 109 hm³La Llosa del Cavall73.75%Capacity: 80 hm³

Cuencas Internas del País Vasco

Capacity21 hm³

Stored water15 hm³

Main reservoirs

Ibai-Eder63.64%Capacity: 11 hm³Urkulu80.0%Capacity: 10 hm³

Duero

Capacity7,602 hm³

Stored water3,533 hm³

Main reservoirs

Almendra51.76%Capacity: 2,649 hm³Ricobayo34.76%Capacity: 1,145 hm³Riaño37.44%Capacity: 641 hm³Santa Teresa46.37%Capacity: 496 hm³

Ebro

Capacity7,813 hm³

Stored water3,511 hm³

Main reservoirs

Mequinenza55.86%Capacity: 1,373 hm³Canelles44.92%Capacity: 679 hm³Ebro52.68%Capacity: 541 hm³Yesa13.2%Capacity: 447 hm³

Galicia Costa

Capacity684 hm³

Stored water320 hm³

Main reservoirs

Portodemouros42.42%Capacity: 297 hm³Eume65.85%Capacity: 123 hm³Fervenza35.92%Capacity: 103 hm³Ribeira, A51.52%Capacity: 33 hm³

Guadalete-Barbate

Capacity1,651 hm³

Stored water1,231 hm³

Main reservoirs

Guadalcacín II84.0%Capacity: 800 hm³Barbate67.98%Capacity: 228 hm³Zahara-El Gastor64.57%Capacity: 223 hm³Bornos63.5%Capacity: 200 hm³

Guadalquivir

Capacity8,030 hm³

Stored water5,504 hm³

Main reservoirs

Iznájar73.59%Capacity: 920 hm³Breña II, La76.55%Capacity: 823 hm³Negratín57.97%Capacity: 571 hm³Tranco de Beas71.54%Capacity: 506 hm³

Guadiana

Capacity9,538 hm³

Stored water6,849 hm³

Main reservoirs

La Serena81.64%Capacity: 3,219 hm³Cijara75.55%Capacity: 1,505 hm³Alange50.82%Capacity: 852 hm³Orellana73.02%Capacity: 808 hm³

Júcar

Capacity2,846 hm³

Stored water1,479 hm³

Main reservoirs

Alarcón71.11%Capacity: 1,118 hm³Tous - La Ribera13.98%Capacity: 379 hm³Contreras68.42%Capacity: 361 hm³Benagéber36.65%Capacity: 221 hm³

Miño - Sil

Capacity3,030 hm³

Stored water1,567 hm³

Main reservoirs

Belesar27.02%Capacity: 655 hm³Portas, Las51.12%Capacity: 536 hm³Bárcena60.7%Capacity: 341 hm³Bao81.09%Capacity: 238 hm³

Segura

Capacity1,140 hm³

Stored water553 hm³

Main reservoirs

Cenajo56.52%Capacity: 437 hm³La Pedrera35.77%Capacity: 246 hm³Fuensanta70.48%Capacity: 210 hm³Algeciras17.78%Capacity: 45 hm³

Tajo

Capacity11,056 hm³

Stored water5,817 hm³

Main reservoirs

Alcántara49.4%Capacity: 3,160 hm³Buendía46.74%Capacity: 1,705 hm³Valdecañas58.78%Capacity: 1,446 hm³Gabriel y Galán37.76%Capacity: 911 hm³

Tinto, Odiel y Piedras

Capacity229 hm³

Stored water140 hm³

Main reservoirs

Piedras36.67%Capacity: 60 hm³Sancho82.76%Capacity: 58 hm³Jarrama60.47%Capacity: 43 hm³Olivargas72.41%Capacity: 29 hm³

Data: MITECO · AEMET