Bidasoa river


The name Bidasoa given to the river may be related to the ancient Vascon town of Oiasso with the Basque term “bide” (meaning way or route) as a prefix, so the whole name means “route to Oiasso”. This would make sense since the final stretch of the route from Pompaleo (modern-day Pamplona) to Oiasso runs right alongside the river. A second theory says that the second half of the term comes from the Celtish word “asa” or “assa” (meaning water) which would mean Bidasoa, in this case could be taken to mean “route to the water”… in other words the path the Bidasoa river follows to the sea. And finally, some claim the name comes from the latin phrase “Via ad Oessonem” (route to Oiasso). Whatever happens, all three names illustrate the rivers function as a communication path.

Source and course

The Bidasoa river is 66 km long. Its source is in Astaté, near the village of Erratzu where the Izpegui and Iztauz streams come together. At its head, it is known as the Baztán river with the name changing to Bidasoa after Oronoz-Mugairi.

The Bidasoa reaches the Cantabrian Sea at Txingudi bay next to Cape Higuer between Hendaye and Hondarribia, forming the Chingudi wetlands that include Jaizubia floodplains, Plaiundi. The Bidasoa islands and Fiasan (Pheasant) Island.

After Urdaibai in Bizkaia,  this area is the second largest maritime wetland in the Basque Country. In 1988 Plaiaundi Environmental Park was created within the wetlands, an excellent example of how to restore a dried up degraded wetland to its original state.  


Several protected wildlife species can be found in the area including mammals such as European minks, otters and the Pyrenean muskrat; reptiles such as the freshwater turtle and birds including the kingfisher and the dipper. The Bidasoa wetlands have environmental interest because they provide refuge and food to fish, amphibians and migratory birds flying from the north of Europe to the south of the Iberian Peninsula and Africa. The trout and salmon that swim upstream to spawn are two of the Bidasoa’s emblematic species. Other non-native species of flora and fauna to be found in this this natural ecosystem include the Ebro nase, the rainbow trout, the coypu and acacias.