Avian group SEO Birdlife brought the case to court. It discovered the regional government of Castile and León had concealed official environmental reports highlighting the importance of a local bird species, the urogallo, in the vicinity of the Peña del Gato wind project.
The plant is located in the Omaña and Cepeda districts, close to the world's southernmost population of the urogallo.
SEO Birdlife is considering whether to call for a precautionary closure of the Peña del Gato, pending the verdict of the developer's appeal, which can take several years.
The ruling is the second threatened closure of an operational wind plant in Spain. An appeal is still pending against a court ruling to dismantle 25 of 33 turbines at developer Acciona's 49.5MW Serra de Tallat plant in Catalonia.
Enel Green Power's press office told Windpower Monthly it will appeal the court decision, adding: "The company wishes to reiterate that it has complied with all relevant legislation for the construction of the wind farm and submitted all permitting documentation requested by law."