The Estuary of Bilbao 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 instance, the Spanish word estuario is used to describe what in English would normally be called part estuary, part tidal river. The estuary becomes a tidal river which extends 16 km (9.9 mi) into the city of Bilbao, starting from the Bilbao Abra bay. It hosts the port of Bilbao throughout its length, although the Port Authority has recently restored most of the upper reaches to Bilbao and other municipalities for their urban regeneration. The port is now being transferred to the seaboard on the coast at Santurtzi and Zierbena.