The River Tinto belongs to the Guadiana basin, rises in the foothills of the Sierra de Aracena (Huelva) and flows 100 km through the provinces of Huelva and Seville to reach the Huelva estuary, where it joins the River Odiel. In the province of Seville, it only runs through El Madroño, where two of its tributaries, the Rivera del Jarrama and the Arroyo del Gallego, serve as its western and southern limits, respectively. Part of the upper and middle sections of the River Tinto is a Protected Landscape. About 225 ha of the protected area belongs to the municipality of El Madroño.
The river acquires its unique features as it flows through the Rio Tinto mining area, regarded as Europe’s largest opencast mining site, in the Iberian Pyritic Belt. The Belt is part of the South-Portuguese Zone of the Iberian Massif. This river is highly acidic and low in oxygen. The ferruginous salts that have contaminated its waters over the centuries give it its characteristic rusty-red colour. Given these conditions, riparian vegetation nor vertebrates can inhabit its banks and surrounding area. However, a large variety of microorganisms is present in its waters. NASA is conducting studies in this area, given that the River Tinto’s environmental conditions could be similar to those of the subsoil on Mars.
Address: Free Access. From El Madroño take the SE-9200 road towards Berrocal (Huelva). There is a dirt track about 700 m away that connects with the former Palomares road. On the left are several paths that lead to the River Tinto.