Nervión

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Image:Delika.jpg The river Nervión runs through the city of Bilbao, Spain into the Cantabrian Sea ( Bay of Biscay ). It is also known as ría de Bilbao/Bilboko itsasadarra ("Bilbao estuary") on its final tract, from the joining with Ibaizabal river to the sea.

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Geography

The river is 72km long from its source at the Burgos and Alava provincial limits to the sea and runs in South to North direction. Soon after its source, the river forms a spectacular 300m waterfall in the Delika canyon (Alava) and then enters the Biscay province through the town of Orduña.It goes into Alava again trough towns of Amurrio and LLodio. Then the river runs again into the Biscay province until the sea, entering the Bilbao metropolitan area at Ugao-Miraballes. The tidal influence reaches 15km inland from the sea, at Bilbao's old town.

The main tributaries are:

From the west:Kadagua and Galindo.
From the east: Arratia, Ibaizabal and Asua.

Ibaizabal is considered by some to be an equally important river, so the whole system is often called Nervion-Ibaizabal and the final tract just "ría de Bilbao". The basin area is 1.900 km².

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History and Economy

Image:Nervion.jpg Image:Granbilbao.jpg From ancient times, the Orduña pass that links Spain's inner plateau with the Nervion valley has had a great economic impact. During the Middle Age it served as a natural border between the Biscay lordship and Castille counties, entry taxes were collected there. Through the centuries, the Nervion valley was a vital communication corridor for Biscay, and the main railroad from Bilbao to the rest of Spain was constructed following the river in 1870.

At the same time, Bilbao developed a great comercial activity, with its seaport being the most important in the north coast of Spain. The port's activity relied totally in the navigability of the river in its final 15km. So engineer Evaristo Churruca developed an enormous project that would solve the traditional navigation problems of the river:

Dangerous sand banks that changed the course constantly.
Many complicated meanders.
Large extents of marsh.
The Bay of Biscay storms that hit the river's mouth.

The river banks where drained and docks were built, the river's course was straightened, the external port was enclosed, and the Puente Colgante transporter bridge was built. By 1900 Bilbao had Spain's biggest port. This allowed the fast development of the region's economy, and shipyards and steelmills covered the banks of the river.

Now the Nervion river has lost economic importance, the navigable part of the river is being abandoned in favour of the external port, to allow urban development to take place in the banks of the river after the dismantlement of the industry.

See Bilbao Maritime Museum: http://www.museomaritimobilbao.org

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Environment

After a century of intense industrial activity the river, specially the final 25km, was ecologically dead with oxygen levels below 20% of normal, being one of the most polluted rivers in the world. In 1990 the local authorities launched a plan to overcome this situation, resulting in a constant improvement of the environmental status that after 15 years has transformed the Nervion in a clean river, full of acuatic life.