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Publications Freshwater in Europe Major European Watersheds Tagus

Freshwater in Europe - Facts, Figures and Maps
- Contents, Credits
- Summary
- Freshwater Resources
- Freshwater Consumption
- Freshwater Quality
- Freshwater Ecosystems
- Major European Watersheds
- Water Policy and Institutions
- Glossary
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Fresshwater in Europe in PDF

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TAGUS

Latin: Tagus, Portuguese: Tejo, Spanish: Tajo.

Length (km): 1 100
Drainage Area (km2): 88 700
Discharge (m3/s): 600
Countries: 2
Population: 9 000 000
Sea at Mouth: Atlantic
Ramsar Sites: 2

The Tagus River rises in east-central Spain, in the Sierra de Albarracin at an altitude of 1 590 meters, and flows through Portugal where it empties in the Atlantic Ocean near Lisbon. It is the longest river on the Iberian Peninsula. The river’s main tributaries are the: Jarama, Alberche, Tietar, Alagon, Guadelia, Almonte and Salor Rivers in Spain and the Erges, Ponsul, Zezere, and Sorraia Rivers in Portugal.

Two European capitals with a total of 11 million people depend on the river for their water supply. It is navigable for about 160 km from its mouth, while dams harness its waters for irrigation and hydroelectric power, creating large artificial lakes.

The lower and upper courses pass through deep gorges and are broken by waterfalls. There have been efforts to reforest the land surrounding the river.

Of the total water demand, 80% is for agriculture and the 20% remaining for drinking-water supplying both Madrid and Lisbon. Further uses include the disposal of waste water, recreation, and basic ecological functions.

Part of the flow in Spain is diverted to the Segura basin, supplying 1.5 million people in southern Spain with drinking water, providing irrigation and supporting the ecosystem in the La Mancha Nature Reserve.

The Tagus basin is managed by a basin organization in Spain, the "Confederacion Hidrografica de Tajo" (CHT), and by the National Institute for Water, INAG; in Portugal three Regional Water Departments oversee its management.

The total storage capacity of the numerous reservoirs in the Tagus basin corresponds to 74% of the average annual runoff. In most of the basin natural flow conditions have now been replaced by regulated flow.

The main environmental pressures on the River are pollution from industrial and municipal point sources and diffuse sources.

Tagus-Segura Transfer

The Tagus-Segura Transfer from the Iberian System in Central Spain to the Mediterranean Levante Zone has been operating since 1979, and has caused severe impacts in both river basins:

Increasing water deficit: The water demand in the receiving basin has doubled in 24 years to 500 million m³ due to the increasing requirements for irrigation and tourism.

Habitat destruction and promotion of unsustainable agriculture: The increase in irrigated land and tourist activities has led to the destruction of thousands of hectares of protected natural areas.

Black market for water and illegal water uses: Water uses are partially uncontrolled. More than 100 million m³ of transferred water “disappear” illegaly to supply tourist resorts and golf courses.

Water over-exploitation in the Tagus donor basin and, as a consequence, chemical contamination and the deterioration of the River ‘s ecosystem: Even in normal summers, the River no longer flows in some places, let alone during critical periods of drought. The legal minimum flow of 6m3/s is not respected.

Social imbalances have increased as the transfers mainly benefit big agro-businesses and construction companies, marginalizing traditional farmers. Illegal immigration and exploitation of immigrants are increasing with about 30% undeclared labour.

Tagus Basin Authority: www.chtajo.es

Instituto da Água - Portugal (INAG): www.inag.pt