13 julio, 2024

Miño River: source, route, mouth, tributaries

He Minho river It is located in the northwest of Spain. It starts in the Sierra de Meira at about 700 meters above sea level, crosses the autonomous community of Galicia and in its final stretch forms the border between Spain and Portugal. It flows into the Atlantic Ocean after traveling approximately 320 km.

It has a hydrographic basin of 12,486 square kilometers and, together with its main tributary (Sil river), it becomes one of the main power generation centers for Spain. Its hydrographic strength in the Atlantic region of the Iberian Peninsula is only surpassed by the Duero River, and it is counted among the eight main rivers in this region.



Since the Quaternary, this area served as a refuge for different plant species that had to survive the cold, such as ferns and aquatic bivalves mainly.

This fluvial corridor also served for ancient settlers to settle on its banks and take advantage of it to irrigate their agricultural crops, consumption at home and their animals. With this, little by little they were altering the ecosystem.

An example of the above can be found in the construction of bridges, roads or diversions to crops, among others. Among the most famous are the Roman bridges built to the west of the city of Lugo and in Ourense around the year 100 AD.

Near the river bank, in Lugo, the Romans built the baths, dedicated to taking hot and cold baths and even exercising. These were built approximately in the year 15 a. c.

The Puente Mayor, in Ourense, was remodeled in the 12th century and later underwent other changes. It is said that Bishop Lorenzo, one of his protectors and restorers, had decreed the exclusive right that only he could fish in the river.

Source, route and mouth

The Miño river is born in the province of Lugo, specifically in the Irimia scree, in the Meira mountain range, in the municipality of the same name. The route it takes through the upper zone was declared in 2002 as a Biosphere Reserve, to protect 360,000 hectares of life.

In its middle section it runs through the province of Ourense, in a fairly flat territorial extension and without major geographical accidents. In its last 73 kilometers it represents the border between Spain and Portugal, giving way to a wide estuary where it meets the Atlantic Ocean, where it flows into.

Characteristics of the Miño river

In its almost 320 km of route, this river divides the Autonomous Community of Galicia, in Spain, in two and has an average flow of 340 m3/s. Along with its main tributary, it is the largest river in the area.

Within what refers to its presence in Spain, it ranks as the fourth river with the highest flow behind the Duero, which occupies first place with 675 m3/s; del Ebro, in second place with 600 m3/s; and the Tagus in third place with 444 m3/s.

On the other hand, it ranks eighth in terms of distance, behind the Tagus River with its 1,007 km distance, the Ebro River with its 930 km, the Duero with its 897 km, and the Guadiana River with its 744 km. , of the Guadalquivir river with its 657 km, of the Júcar river with its 498 km and of the Segura river with its 325 km distance.

Likewise, it is the eighth river with the largest hydrographic basin, surpassed by the Duero with 97,290 km², the Ebro with 86,100 km², the Tagus with 80,600 km², the Guadiana with 87,733 km², the Guadalquivir with 57,071 km², the Júcar with 21,597 km² and the Segura. with 18,870 km².


Being a river that runs through almost the entire Autonomous Community of Galicia and part of the border with Portugal, with some cities and towns on its banks, it is not safe from the dangers of human action that contaminate it.

In January 2019, an alert was published by the Aquamuseum of Vila Nova de Cerveira, in Portugal, reporting the appearance of microplastics consumed by aquatic species that inhabit the river.

The finding was made in the stomach of a fish known as pejerrey after studies were carried out by the Aquamuseum and the universities of Vigo and Porto, dedicated to the conservation and protection of migrating fish.

According to Carlos Antunes, director of Aquamuesum, microplastics can be identified in two groups, primary and secondary. The first have to do with microspheres used in the industry as raw material to produce plastic products, the second can come from containers, fishing nets and plastic bags.

The concern is widespread because this material, in addition to contaminating the natural environment, can be consumed by humans once they eat the affected fish and shellfish, for example.

In 2014, the Galician Nationalist Bloc (BNG) also alerted about the presence in the river of bio-supports, tiny pieces of plastic used in the treatment to purify wastewater from municipalities, agriculture or fish farming.

On other occasions there have been reports of diesel spills, the presence of the so-called «Asian clam» and even dried up areas of the river that end up affecting it.

Number of dams in the Miño riverbed

This river concentrates five of the 350 reservoirs built in Spain, which produce a total of 426 GWh per year. The largest of them is called Belesar, created in 1963 with an installed capacity of 300 MW; then the Peares reservoir, created between 1947 and 1955, with a capacity of 159 MW; then the Frieira reservoir, built in 1967 with a capacity of 130 MW; the Castrelo reservoir, created in 1969 with a capacity of 112 MW; and also the Velle reservoir, created in 1963 with a capacity of 80 MW.

Given the number of dams established along the river, it is only navigable transversally and in short longitudinal journeys. In the Castrelo dam there is a nautical park that has become an important tourist and sports attraction.

A feature presented along with the construction of the reservoirs, carried out in the 1960s and some updated in more recent years with extensions, resides in the impossibility for fish species to go up the river to carry out their natural mating process. In addition to having had to flood fertile land dedicated to agriculture and even small towns.

Roman bridges over the river

In the first century before our era, in their expansionist desire, the Romans reached the Iberian Peninsula to settle for several centuries. This allowed the intervention of geography with architectural infrastructure that can be seen today.

Of this architecture, at least 40 bridges remain standing, despite the fact that a large part of them have been restored, remodeled and intervened in different periods of history until almost making their original structure disappear. Of these constructions, two cross the river Miño.

The oldest of these buildings is in the town of Ourense, 370 meters long and 5 meters wide. It has its origin in the mandate of the Roman emperor Trajan, known for being one of the last interested in expanding the borders of the empire and for his commitment to the construction of works. It was rebuilt in the 13th century and declared a National Monument in 1961. Twenty centuries later, since 1999, it is only allowed to be explored by pedestrians.

Another bridge, of equal antiquity, is in Lugo and led to Santiago de Compostela, along the old Roman road. It is 104 meters long and 4 meters wide, although at first it measured 7 meters. It was used as the main entrance to the city and communicated with Bracara Augusta. It underwent renovations during the 12th, 14th, 18th and 21st centuries, which made it pedestrian since 2014.


The Miño River is navigable for short longitudinal and transversal routes, however, it is very important in terms of hydroelectric power generation for the rest of the country, as it contains a total of five reservoirs in its riverbed.

It also has a great tourist attraction that is very representative for the towns bordering the river, especially for those that still preserve and protect the legacy of Roman constructions such as bridges, walls, baths and emblematic sites such as the primitive road to Santiago and the wine route. .

Other cities located on its banks also promote sports activities, including training for the Olympic Games, in the river’s reservoirs.

Main cities that it travels

The city of Lugo, capital of the province with the same name, is one of the most important that crosses the Miño. It dates back its origins beyond the Roman invasion that occurred in the 1st century BC. C. on a Celtic castro called Lug, later renamed as Lucus Augustus by the Roman emperor, who gave it the rank of capital of legal convent.

With a population of 98,268 inhabitants at present, in an area of ​​329.78 km2, it is behind Ourense with 105,893 inhabitants in an area of ​​84.55 km2.

The latter, also crossed by the Miño, is the capital of the province of the same name, created in a Roman camp on ancient settlements of its original inhabitants, later turned into an important city thanks to the exploitation of gold. It is the third city in Galicia with the highest population density. In addition, it has an important commercial nucleus.

Within the province of Lugo there is another city located on the banks of the river called Puertomarín, with almost 1,500 inhabitants. The city of Ribadavia is also in the province, with about 5,000 inhabitants in an area of ​​25 km2.

In the province of Pontevedra are Salvatierra de Miño, with almost 10,000 inhabitants in some 62 km2; Tuy, with a population of just over 16,000 inhabitants distributed over 68 km2, Tomiño and La Guardia, with almost 13,500 and 10,000 inhabitants respectively.


The Sil river is the main tributary of the Miño. Its distance is 40 km long and it is about 500 meters deep, extending for 6,000 hectares. It runs through part of the Province of Lugo and Ourense, its average flow is 100m3/s and it rises at 1,980 meters above sea level.

Among other secondary tributaries is the Neira River with a length of 56 km, the Avia with a length of 37 km, the Barbantiño with a length of 15 km and the Arnoia River with a length of 58 km.


As far as flora is concerned, the Miño River is characterized by being a bioclimatic region of the Atlantic, which is why it preserves various typical species of the area.

Although many have been affected by human intervention, urbanization of areas, creation of reservoirs and dumping of waste, among others, it is still possible to find some threatened species such as the water lily (Nymphoides peltata).

The oak groves are also threatened by various factors, in addition to those already mentioned, there is also the danger of fires and grazing. Riverside vegetation is very common thanks to the legislation dedicated to its protection.

Some of the riparian species consist of oak, willow, poplar, bramble, pine, chestnut and fern. Also the cork oaks, shrubs, alders and marsh violet. In minor…

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