Vilarinho da Furna was a village in the northern Portuguese national Park Peneda-Geres. It was flooded when an hydroelectric dam was built in 1970. In summer, when the water level is low, the ruins can be seen. (Pictures from Antunes, 2001 - be so kind and click on them if you want to see them propperly).
This is an extract from an e-mail I received today (emphasis added):
"the fact that we have water from a damn that provides for the whole region all year round"