The Tagus Estuary

The Tagus Estuary is considered one of the 10 most important wetlands in Europe and the most important and extensive wetlands in Portugal. Its importance is recognized especially due to the great amount of aquatic migratory birds it receives.

The habitats of the estuary form a mixture of salinity, humidity and vegetation, creating the necessary conditions for great biological richness.

The marshlands area of the Tagus Estuary is considered the largest continuous area and with greater significance in Portugal. The marshlands have a great concentration of organic matter, due to the sediments brought by the river and to the decomposition of the plants that develop in it, being, therefore, an area of great biological productivity. The main primary producers of the estuary are in the marsh, these are special plants, because they are adapted to high concentrations of salt in their environmental.

In places where the water is less brackish, the reed dominates the vegetation, forming extensive areas of reed that several bird species use to build their nest.

The salinas are a result of the transformation of old marshlands in structures designed for salt extraction that are formed by different types of tanks with a variable water height.


Located in the heart the most important wetland of Portugal, the Tagus Estuary Natural Reserve, EVOA – Tagus Estuary Birdwatching and Conservation Area, allows the visitors to know and enjoy the unique heritage that we have between the Lezíra and the Tagus Estuary.

Three freshwater wetlands are integrated in EVOA, in a total of 70ha. These lagoons are very important for the birdlife, being used as refuge areas or as nesting areas.  To guarantee the tranquility of the birds and to maximize your experience and comfort during the visitation there are three observatories in the lagoons, several inconspicuous viewpoints and a Visitor Centre.

The Visitor Centre besides from welcome the visitors, invites you to know our permanent exhibition – EVOA, Where the World Meets the Tagus – and to participate in the different activities that are complementary to birdwatching.

However the birdwatching experience begins when you enter the South Lezíria from Vila Franca de Xira: the contrast between landscapes, the relation between tradition and innovation and, of course, the variety of species that feed and take refuge in the canals, in the agricultural fields and in the Lezíria’s pasture lands. Welcoming everyone who inhabit this fascinating place.


EVOA has as principal motivation the conservation of birdlife from the Tagus Estuary and the Lezíria from Vila France de Xira within the natural and agricultural habitats from which depends. For this we pretend:

  • Create conditions that attract the biggest diversity possible of birds occurring in the estuary and in the lezíria;
  • Create conditions for birdwatching, in tranquility, for whom already has some experience;
  • Contribute to dissemination of bird conservation importance as well as to facilitate its scientific study;
  • Increase the intertidal area available for estuary wintering birds;
  • To increase the suitable areas for nesting for the different species of aquatic birds;
  • To divulge the construction and conservation work of the Lezíria;
  • Raise awareness of the importance of water management, for which the Lezíria is an excellent example;
  •  Demonstrate a model of self sustainability in the management of Nature Conservation.