Hydrography

The Nalón River

The largest river in Asturias is the Nalón, whose waters run from southeast to northwest through the region, cutting through narrow mountains, wide meadows, and charming towns. The river waters the valley's mining basins, which is why "El Presi" sings to the Nalón like a young miner singing his way down to the sea. Its mining past and how large it is, make this river part of the soul of Asturias.

The Nalón River starts at the border with Castilla y León in Puerto de Tarna (Caso) and flows down to the Cantabrian Sea between Esteban de Pravia and San Juan de la Arena. It is about 140 km long, passing through such iconic towns as Campo de Caso, Rioseco, Pola de Laviana, Langreo, Soto de Ribera, Grado, and Pravia.

Not only is it the longest river in Asturias, but also the largest in terms of volume. Two reservoirs were built to manage its waters: the Río Seco and Tanes reservoirs.

The Nalón river basin is quite large, feeding 36 towns, which represent more than half of the autonomous community's municipalities. Its tributaries are the Narcea (110.9 km), the Nora (77.6 km), the Trubia (31.3 km), the Cubia (28.8 km), the Aranguín (21.9 km) and the Caudal (20.6 km).

The Nalón has been an important river that has attracted numerous settlements and brought much prosperity to the area. Its banks have been occupied since Paleolithic times as is seen in the prehistoric caves of the middle and lower basin, such as the Peña de Candamo cave. The Transmontane Asturian peoples also settled in the area, and later the Romans, who left their mark with bridges and fortresses that were later re-purposed.

In the 18th century, the waters of the Nalón River turned black. It is located on one of the areas with the largest deposits of hard coal in Asturias. This resource was a turning point for industrialisation in the area, creating new mining settlements like Sama de Langreo, San Martín del Rey Aurelio, and Laviana. In addition, development was further bolstered by the expansion of other steel companies. Visitors can see this part of the Nalón Valley's history at the Samuño Valley Mining Ecomuseum in Langreo and at the Asturian Mining and Industry Museum in San Martín del Rey Aurelio.

The industrial boom caused enormous water pollution from coal washing and mining waste. As a result, the trout, eels, lamprey, and salmon that were abundant in the river were more difficult to find. However, the situation has been gradually reversing.

There is a wide variety of protection measures that protect the river's ecosystem like LICs (Sites of Community Importance) and ZEPAs (Special Protection Areas for Birds). Likewise, the upper section of the river is located in the Redes Natural Park and Biosphere Reserve, which is an immensely rich natural environment.

Another river-related event is the Folkloric Descent of the Nalón, which has been a National Tourist Event since 2020. It is held on the Saturday between the 19th and 25th of August in Pola de Laviana, the capital of the council. More than 2,500 people participate in this entertaining water event. They dress up and ride on colourfully decorated boats; undoubtedly an experience not to be missed.