Miño.
Miño.
Key features of the case study
The Spanish energetic policy in the beginning of the economic and industrial development of the country centered great part of its objectives on the usefulness of the hydroelectric potential of the mayority of the Spanish rivers. In this context, between the years 1950 and 1990, 939 were built in the whole world, being 46 them are in Galicia.
The Frieira dam was built in 1970 and as in the design of other big dams, regardless of environmental criteria. As a consequence, the dam has brought substantial negative efects. The "barrier effect" causes the interruption of the longitudinal continuity of the Miño river and the fish migrations.
The Frieira dam is the first obstacle of the river, as it is located at aproximately 68 km from the mouth to the Altanlic Ocean. Upstream, the continuity of the Miño river is interrupted by four more dams that stop the fish access to headwaters: Castrelo, Velle, Peares and Belesar. There are tho rivers upstream the Frieira dam, the Avia river (37 km of main course, with an area basin of 643 Km2) and the Arnoia river (58 Kms of main course and 923 Km2 of basin ) and other three rivers of less entity (Deva, Cierves and Brull) that could provide refuge and spawn areas to the migratory fish.
Anyway, the Avia river is regulated by the Albarellos dam [1] and the Arnoia river has four transversal barriers[2] (small hydroelectric) some of them with fish passage (so far we do not have reliable data).
The Frieira dam is 33 m high with 194 m long at the top. It has a storage capacity of 44,41 Hm3 and a surface of 466 ha. The main effect is on the migration of fish species as atlantic salmon (Salmo salar), eel (Anguilla anguilla) , "reo" (Salmo trutta), lamprey (Petromyzon marinus) and "sábalo" (Alosa alosa). It has also negative effects on the populations of the naiad (Margarita sp.) and fish predators as the huron and the otter. the result is a loss of biodiversity a decrease on fish population, and a impoverishment on the social and economic benefits of the river and the activities related with fish (mainly, recreational fishing).
Previously, a passage for eels was built, with ineffective results.This project was conceived as pioneer and innovative in the context of environmental restoration, with the aim of recover the aquatic habitat and fish populations at the low Miño river.
Site description
Measures selection
Success criteria
Ecological response
Hydromorphological response
Monitoring before and after implementation of the project
Socio-economic aspects
Contact person within the organization
- Unión Fenosa S.A., (Xunta de Galicia)
- María Luisa Prada Hervella
- Carretera de Monforte, S/N, ES, 32960
- Telephone: +34988235211
- Fax: +34988238603
- E-mail: mlprada@uef.es
- Website: www.unionfenosa.es
Extra background information
References
The Miño at the Frieira dam, during the winter of 2010 [1]
