The Zadorra is a river tributary of the

Ebro The Ebro (Spanish and Basque ; , , ) is a river of the north and northeast of the Iberian Peninsula, in Spain. It rises in Cantabria and flows , almost entirely in an east-southeast direction. It flows into the Mediterranean Sea, forming a de ...

in the Basque Country in the north of the

Iberian Peninsula The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprisin ...

. The river flows primarily across Álava

province A province is an administrative division within a country or sovereign state, state. The term derives from the ancient Roman , which was the major territorial and administrative unit of the Roman Empire, Roman Empire's territorial possessions ou ...

(flowing briefly through the Treviño enclave at La Puebla de Arganzón) finally reaching the Ebro near Miranda de Ebro in Burgos province, Castille and León. The river's water volume is the largest in Álava, with its basin being the most extensive in the province. Nowadays it provides by means of the Zadorra Reservoir System (comprising reservoirs Uribarri-Ganboa, Urrunaga and Albina) water supply for Vitoria and half of the Basque Autonomous Community. The river rises in the slopes of the Entzia Plateau at the spring known as Los Corrales (municipality of San Millán/Donemiliaga), meandering thereafter across the Alavan Plains to the west (loops around Agurain/Salvatierra) past Vitoria by the north, where it takes a turn to the south heading to the Ebro through La Puebla de Arganzón.

Landmarks

* The village and iconic castle of Gebara sit by the river on its middle stage. * The Zadorra Reservoir System starting in Uribarri-Ganboa (built as of 1947). * The

Battle of Vitoria At the Battle of Vitoria (21 June 1813), a United Kingdom of Great Britain and Ireland, British, Kingdom of Portugal, Portuguese and Spanish Empire, Spanish army under the Arthur Wellesley, 1st Duke of Wellington, Marquess of Wellington bro ...

took place on a stretch extending on the banks of Zadorra from La Puebla de Arganzon to Trespuentes to Mendoza. Site in Spanish * The site of old Basque-Roman town Iruña-Veleia is across the river from Trespuentes.

Pollution

The Zadorra is the most important river in Álava and is also the most polluted. It ranks in the top six polluted rivers in the Basque Country. More than 2,754

waste Waste are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor Value (economics), economic value. A wast ...

disposals have been authorised, 1,783 (65%) of which are urban and 960 (35%) of to which are industrial. From the 960 industries 89 of them are subject integrated environmental authorization. Unauthorized waste disposal also must be taken into account for the pollution. Additionally, waste dumped by industries is often more polluted than it should be. The

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

levels in the Zadorra are below the standards required for the

wildlife Wildlife refers to domestication, undomesticated animals and uncultivated plant species which can exist in their natural habitat, but has come to include all organisms that grow or live wilderness, wild in an area without being species, introdu ...

in the river. The river's situation is also aggravated by the presence of toxins. The level of toxins is above the amount allowed by the European Union. Fifteen wastewater treatment plants have helped stopping the advance of the pollution in the river. The kind of insects that nest in the river are an indicator of the degradation of the Zadorra. Because the insects show in the top of the river what is happening in the bottom of it. In addition, nitrates have appeared in the river, despite the amount of nitrates being low, there should not be any nitrates. In 2008 the

's hydrographic confederation published a report about some of the rivers around the Ebro, including the Zadorra river. The investigation, which measured pollution in the rivers over four years, started in 2004. The report showed that the amount of pollution found in the river was well over the permitted amount. As a result, the municipalities have started some control programmes for the authorization of waste disposal. The control programmes have brought about some reduction in pollution.

References

{{Coord, 42, 40, 03, N, 2, 53, 59, E, type:landmark_source:kolossus-frwiki, display=title Rivers of Spain Ebro basin Rivers of Álava Rivers of Burgos Rivers of the Basque Country (autonomous community) Rivers of Castile and León