The district is conformed by 7 municipalities: Aljaraque, Ayamonte, Cartaya, Gibraleón, Isla Cristina, Lepe and Punta Umbria, these are the municipalities of the county of Huelva located among the mouth of the river Guadiana and the estuary formed by the rivers Tinto and Odiel when arriving at the sea, occuping an extension of 942 km2.

It is a territory of recent colonization, located at the ending tract of the sedimentary basin of Guadalquivir, open to the Atlantic sea and bordering at the west on Portugal, that already has the appropriate infrastructures to link with the neighbouring country.
The economy of the area is based traditionally on the agriculture, the new agriculture, the fishing and, in smaller measure, the forestry. The tourist sector, is now in development process in this tract of the Huelva´s coast, being up to now limited to second residence for holidays.

© Photograph: Francisco Jiménez.

Avifaunal diversity: 210 species of present birds which suppose 40% of 524 described at the publication Birds in Europe (Birdlife 2004).

Threatened species: 98 threatened species.

Importance for the aquatic birds of Western Paleartic: Among the present bird groups in the district, the most important, regarding number of species and size of the populations, are the aquatic birds.

Natural Protected Spaces. A very significant percentage of the regional surface is protected by some autonomous figure, of European Union or International.

The presence of Important Bird Areas (IBA). River Tinto and Odiel marshes and coastal lagoons of Huelva, River Piedras and Flecha del Rompido, Isla Cristina and Ayamonte marshes and Prado Hondo Lagoon.