Reservoir of Arenós Nature · Puebla de Arenoso, El Alto Mijares, Castellón The Arenós reservoir, also called Arenoso or Campos, is situated on the bed of the río Mijares as it passes through the municipalities of Montanejos and Puebla de Arenoso, in the Alto Mijares. It is an embankment dam made of loose materials, of rockfill with a clay core, built between 1970 and 1977, 109 metres high, about 500 metres thick at the base and 428 metres long at the crest; it covers 418 hectares and stores up to 136.9 hm³, making it the second-largest reservoir in the Comunitat Valenciana by capacity. It was built to regulate the río Mijares and irrigate 27,000 hectares of La Plana de Castellón, and belongs to the Confederación Hidrográfica del Júcar. Beneath its waters lay the vanished village of Campos de Arenoso, evacuated on 15 July 1977, along with several districts of Puebla de Arenoso. Photo: Sebastian Wallroth (Wikimedia Commons) (CC BY-SA 3.0) What to see and do in Puebla de Arenoso