The ornitological wealth of one of the three more important inner lagoons of Spain, the Nava, made possible that in 1990 the waters of a river again returned to flood 60 hectares of it. The works made in this first intervention tried to delete the water-drainages of the channel network and the drains. Later, the actions contemplated in a project of the UE included the purchase and renting of lands, works of restoration inside and outside the lagoon, activities of management and public use. The recovery project of the Nava has been able to regenerate 300 has of the old lagoon and is generating interesting direct and indirect economic resources, derivative mainly of the tourism. The present crisis of the agrarian sector, specially well-known in Tierra de Campos, teaches us that dangerous political decisions as the destruction of an important natural enclave as the Nava, must count on serious and rigorous reports.