Bidasoa

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The Bidasoa (, ; french: Bidassoa, ) is a river in the Basque Country of northern Spain and southern France that runs largely south to north. Named as such downstream of the village of Oronoz-Mugairi (municipality of Baztan) in the province of Navarre, the river actually results from the merger of several streams near the village ''Erratzu'', with the stream Baztan that rises at the north-eastern side of the mount Autza (1,306 m) being considered the source of the Bidasoa. It joins the Cantabrian Sea (Bay of Biscay) between the towns of Hendaye and Hondarribia.

The river is best known for establishing the borderline at its lower tract. This stretch is crossed not only by aircraft at low height but by important European communication axes, namely AP8 E5 E80 - E70 A63 (motorway, connection at the Biriatu toll), main roads N1 - N10 (connection at the roundabout of ''Saizar'' by the river) and major French and Spanish railway networks,— RENFE and SNCF. Besides these major lines, other regional ones cross it too, e.g. regional railway EuskoTren (terminus in Hendaye) and another double bridge (pedestrians/vehicles) joining the towns on the border, i.e. the historical Santiago Bridge (Way of St. James). At this stage of the river, urban landscape prevails (built-up area).

Before pouring its waters into the ocean, it forms a bay called Txingudi located between these towns and Irun, the site being designated ''Wetland of International Importance'' in 2002, with a total area of . The banks of Hondarribia hold the minor '' San Sebastian Airport'' serving domestic flights and currently mired in controversy over its lengthening and upgrading scheme.

Pronunciation and etymology

The river comprises an area of linguistic contact, so it is pronounced differently depending on the language, namely in Basque, in Spanish, and in French. Linguistic and historic research point to the name stemming from Latin phrase "Via ad Oiassonem" (later corrupting into Basque "Bidasoa") on account of the road that linked at Roman times Basque town Pompaelo with Oiasso, which may have run along the river.

Course of the river and tributaries

The Bidasoa flows through much of its length over Navarrese territory, except for the last , where it establishes the borderline between France and Spain, as well as the boundary between the Basque provinces of Gipuzkoa and Labourd. In line with the distribution of the river's length, the bulk of its watershed's area lies on Navarre (). The basin holds 105 permanent streams and rivers that number , the region being drenched in rains regularly. The Navarrese side of the basin (rural landscape) is inhabited by 22,000 inhabitants. 70% of its population have the sewage treated before spilling to the river.

But for the first 15-odd kilometres, the river clings to the north to south disposition of other neighbouring rivers of Gipuzkoa joining the Bay of Biscay, e.g. Urumea, Oria, etc. Strengthened by the waters harvested from the sides of the pass of Belate, downstream of Doneztebe the river heads north and crosses the town of Bera at the north end of Navarre before entering Gipuzkoa at Endarlatsa. From the town of Doneztebe on, the main road N-121 runs along till the roundabout across the river from the toll of Biriatu