Tagus Basin District

Where is it located?

It is located in the central area of the Iberian Peninsula and extends through Spain and Portugal, it is elongated and oriented from East to West.

The total extension of the Tajo River Basin is 80,925.85 km².

In Spain it runs through 5 autonomous communities: Extremadura, Madrid, Castilla y León, Aragón and Castilla-La Mancha. And in Portugal, it runs through the regions of Beira Baixa, Alto Alentejo and Ribatejo.

The most important river in the basin is the Tagus, which runs from the Sierra de Albarracín, where it has its source, to the Estuary of the Sea of Straw next to Lisbon in Portugal, through the center of the Hesperian Massif in a total distance of 1007 km, 857 km in the Spanish part and 150 km in Portugal.

This slope is embedded between the Central mountain range, to the north; the Montes de Toledo and Sierra de Montánchez to the south and the Iberian Mountains (Serranía de Cuenca and Sierra de Albarracín), to the east. The western limit, as far as the Spanish national area is concerned, is made up of the Tuerto, Erjas and Séver rivers that set the border with Portugal.

The network of tributaries of the Tagus is very asymmetrical, those on the right bank which are the ones that provide the most abundant flows, and which collect the contributions of the Central System and the Iberian mountain range (Jarama, Alberche, Tiétar and Alagón on the Spanish side; Zêzere on the Portuguese side and Erjas on the border).

The left tributaries (Guadiela, Almonte, Salor on the Spanish side; Sorraia on the Portuguese side and Séver on the border) are generally short and have scarce waters, particularly those that originate in the Montes de Toledo.

The main contributions of the basin come from the Sierra de Gredos and the rest of the massifs corresponding to the Central System, as a result of the marked asymmetry of the basin.

In the Portuguese part, the hydrographic region is called the Tagus and Ribeiras do Oeste Hydrographic Region – RH5, with a total area in Portuguese territory of 30,502 km2.

The RH5 encompasses a total of 103 municipalities, 73 of which are completely included in the hydrographic region and 30 are partially covered.

As for tributaries, in Portugal the main ones are the Erges, Pônsul, Ocreza and Zezere rivers on the right bank, while the Sever and Sorraia rivers are on the left bank.

The Portuguese section is marked by important breaks in the slope, first in Puertas de Ródão, the result of the intersection of the hard quartzite relief of the Sierra de las Talhadas with the course of the Tagus, and in the town of Belver.

On the left and south slopes, the hydrographic structure of the basin is totally different. The watercourses have hardly any relief, through the Sever River and the Nisa River, which drain ancient formations, right at the entrance section of the Tagus River to Portugal.

2022-2027 Hydrological Plan

The hydrological plan for the Spanish part of the Tagus Basin District currently in force was approved by Real Decreto 1/2016, January 8, approving the revision of the Hydrological Plans for the basins districts of Guadalquivir, Ceuta, Melilla, Segura, Júcar and Western Cantabrian, and for the Spanish part of the basins districts of Miño-Sil, Duero, Tajo, Guadiana, Ebro and Eastern Cantabrian Sea, in compliance with article 83 of Royal Decree 907/2007, of July 6, which approves the Hydrological Planning Regulations.

On December 22, 2021, the public consultation period for the Draft Hydrological Plan Project for the Spanish part of the Tagus River Basin for the period 2022-2027 ended. After that period, the proposals, observations and suggestions that, where appropriate, are considered appropriate will be incorporated into the hydrological plan project proposal, which will require the mandatory report of the Water Council of the demarcation. Said hydrological plan project proposal, with the agreement of the Committee of Competent Authorities on the program of measures in its corresponding sphere of competence, will be submitted to the Government through the Ministry for the Ecological Transition and the Demographic Challenge, for its approval. The approval of this new review will lead to the repeal of the second cycle Hydrological Plan, approved by Royal Decree 1/2016, of January 8. Once this review has been formalized, it will be notified to the European Commission, a milestone that must occur no later than March 22, 2022.

In Portugal, currently, the Management Plan of the Tagus Basin District in force was approved by Ministry Council Resolution, n.º 52/2016, September 20, corrected by Declaration of Rectification No. 22-B/2016, of November 18, through which the Management Plans of the Hydrographic Region of Continental Portugal for the period 2016-2021 are approved.

Currently, work is being done on the revision of the aforementioned Plan for the period 2022-2027. During the first half of 2021, the projects of the Management Plans of the Hydrographic Regions were submitted to public consultation for a period of six months. The final versions of these plans will be published with a deadline of December 22, 2021.

What are the shared water bodies under study?

Rivers and reservoirs

















ES / PT Name

Río Erjas cabecera / Rio Torto

Río Erjas entre puntos frontera / Rio Erges

Río Erjas medio entre puntos frontera / Rio Erges

Río Erjas desde el punto de Frontera hasta el Embalse de Cedillo / Rio Erges

Embalse de Cedillo / Albufeira Monte Fidalgo (Cedillo)

Río Sever desde pto. fronterizo a E. Cedillo. / Rio Sever

Río Sever de cabecera al punto fronterizo / Rio Server

ES / PT Category

Río / Rio

Río / Rio

Río / Rio

Río / Rio

Río / Rio (Albufeira)

Río / Rio

Río / Rio

ES / PT Nature

Natural / Natural

Natural / Natural

Natural / Natural

Natural / Natural

Muy modificada / Fortemente modificada

Natural / Natural

Natural / Natural

A way to make Europe

Co-financed by the European Regional Development Fund (ERDF)
through the Interreg VA Spain-Portugal Programme (POCTEP) 2014-2020