Problems
The Tagus River, the longest in the Iberian peninsula, is in danger of drying up completely as Spain once again finds itself in the grip of drought. The Tagus, known in Spanish as the Tajo and in Portuguese as the Tejo, rises in Aragón in northern Spain, passes close to Madrid, and forms part of the border with Portugal before flowing into the sea at Lisbon. En route, it is dammed no fewer than 51 times in Spain alone.
Causes of drying up
But its troubles begin at the headwaters in Aragón. In 1902 a plan was conceived to siphon off water from here and divert it to the Segura River to irrigate farms in the arid southeast in what is known as the Tajo-Segura transfer. Construction began in 1966 and water started flowing out of the dammed Tagus headwaters to the Segura in 1979. However, the amount of available water was miscalculated and Spain’s cyclical droughts were not factored in. Today only 47% of the predicted water resources exist and levels in the two headwater dams are down to 11% capacity, too low to allow any transfers. The Tagus’s troubles don’t end with the transfer. Even after about 65% is siphoned to the Segura, it still has to supply Madrid’s 6 million inhabitants, whose inadequately treated wastewater is dumped back into the river further downstream. The water from the Tagus is also used to cool nuclear reactors.
Consequences of lowering water in the Tagus River
The drying up of the Tagus River has serious consequences for both humans and nature. One of the most obvious effects is the loss of livelihoods for millions of people who depend on the river for fishing, farming, tourism, and transportation. The low water level has reduced fishery resources and crop yields, as well as disrupted the navigation and trade on the river. Many people have been forced to migrate or seek alternative sources of income. The drying up of the Tagus River has also increased the risk of poverty, food insecurity, and social conflicts in the region.
Gallery
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Timelines
2020
Tagus River witnessed a massive fish kill that alarmed environmentalists and authorities. High temperatures, low water levels, and poor water oxygenation caused the fish to kill. Thousands of dead fish, mostly carp and barbel, floated on the river surface or the shore. The fish kill affected the biodiversity and the food chain of the river, as well as the fishing industry and the tourism sector.
2019
November 05
The water level of the River Tagus is at a historic low. Its two Portuguese tributaries, the Ponsul and Sever, are depleted and now almost dry, allegedly due to the water management policies of the Portuguese and Spanish governments. In Portugal, the Tagus was without water for 10 months, causing incalculable damage.
2017
Tagus River reached its lowest water level in history, shrinking to just 10% of its usual size. The river entered its dry season in 2016, earlier than at any time since records began. The drought was caused by the lowest rainfall in the Iberian Peninsula since 1995. Human influences such as dams, transfers, and pollution also contributed to the river’s decline.
1902
A plan was conceived to siphon off water from here and divert it to the Segura river to irrigate farms in the arid southeast in what is known as the Tajo-Segura transfer.