The Troncoso River, with a length of 13.61 km and a basin area of1803.31 hectares, belongs to the “silica Atlantic-Cantabrian” class of rivers. It is a tributary of the Miño-Minho river on its right bank, so it is a part of the hydrographic basin of the Miño river. It is located, and is the boundary, between the municipalities of Padrenda (Province of Ourense) and Melgaço.
The Trancoso river runs along the northwestern edge of the continental SCI (sites of community importance) of Baixa Limia (December 7, 2004) and it is noted for its dry and wet moors of Erica cilliaris and Erica tetralis, as well as blanket peat bogs and oak forests of Quercus robur and Quercus pyrenaica, together with a large number of local endemics. Secondly, it is also of a great geomorphologic interest due to the presence of the lowest glacial cirques on the peninsula. As for wildlife, it is worth mentioning the wolf (Canis lupus).Likewise, the Portuguese section of the Trancoso river is part of the Cross-border Biosphere Reserve of Gerês-Xurés and it is located in its transition zone.
The Trancoso river has an excellent status of ecological quality and excellent preservation of its banks and margins, and thus, in the Spanish and Portuguese River Basin Management Plans, it has been proposed that they be River Nature Reserves. The basin of the Trancoso-Troncoso river is, overall, a sparsely populated area and shows no significant signs of disruption, since there are no dams, mining areas, dumps nor great population centers.
Actions proposed regarding planning and management of water resources
The Water Plan 2010-2015 of the Spanish part of the Hydrographic Demarcation of the Miño Sil proposes, first, that by declaring the Trancoso river a Nature River Reserve, it is necessary to provide the control and monitoring steps that will enable the preservation of the natural quality of both the river and the groundwater systems connected to it, giving priority to the criteria on the ecological quality specific to this basin in terms of its climatic, lithologic and biological characteristics, and carrying out the necessary analysis.
In addition, the correct demarcation of the rivers must be ensured giving priority to the preservation/conservation of their banks and demarcating also the so called flood plains.
Finally, as it is located in the SCI (site of community importance) of Baixa Limia, the management of the Trancoso river will have to comply with the provisions arising from this form of protection, in particular, with those established in the Decree 72/2004, which declares this area a Special Area of Conservation because of its Natural Values. In addition, compliance with the provisions established in the Law 9/2001, of the 21st of August, on the Conservation of Nature in Galicia, must be also observed.