The Ibaizabal (''wide river'' in Basque) is a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

that drains southeastern

Biscay Biscay (; eu, Bizkaia ; es, Vizcaya ) is a province of Spain and a historical territory of the Basque Country, heir of the ancient Lordship of Biscay, lying on the south shore of the eponymous bay. The capital and largest city is Bilbao. B ...

to the

Estuary of Bilbao The Estuary of Bilbao (Spanish: ''Ría de Bilbao'' / Basque: ''Bilboko Itsasadarra'') lies at the common mouth of the rivers Nervion, Ibaizabal and Cadagua, which drain most of Biscay and part of Alava in the Basque Country, Spain. In this insta ...

. It is long from its source at Elorrio to the

Nervión , name_etymology = , image = Nervion.jpg , image_size = 300px , image_caption = River Nervion with Zubizuri footbridge. , map = , map_size = , map_caption = , pushpin_map ...

, and it passes by the towns of

Durango Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated in ...

and

Amorebieta Amorebieta-Etxano, also known as Zornotza (Spanish, ''Amorebieta-Echano''), is a town and municipality located in Biscay in the Basque Country, an Autonomous Community in northern Spain. At the time of the 2019 census, the population of the muni ...

and joins the Nervión river at Basauri. Both rivers run then together for a short length until they merge with the sea at

Bilbao ) , motto = , image_map = , mapsize = 275 px , map_caption = Interactive map outlining Bilbao , pushpin_map = Spain Basque Country#Spain#Europe , pushpin_map_caption ...

. It is

disputed Controversy is a state of prolonged public dispute or debate, usually concerning a matter of conflicting opinion or point of view. The word was coined from the Latin ''controversia'', as a composite of ''controversus'' – "turned in an opposite d ...

which river is the one that actually reaches Bilbao. It is commonly agreed that it is the Nervión, but there are some who argue that the Ibaizabal carries more water.

See also