Richard Chapelow, 29, disappeared in the dam’s waters after being flung from a banana-boat-type inflatable during the afternoon of Monday, 20 August.
The search for the Briton was called off on Tuesday this week, after search and rescue teams had scoured the murky waters of the vast dam for more than two weeks.
Commandant Mário Batista, head of the local fire service who was coordinating the search, said it had been called off “after everything possible was done” to find Mr. Chapelow, who is believed to have been holidaying in Portugal with the son of billionaire property tycoon Jon Hunt, founder of Foxtons estate agency.
He was part of a group of 10 Britons enjoying a day at the dam when tragedy struck.
Four people were flung off the banana boat, which was being pulled by a speedboat reportedly carrying a further six people. Only three of the four swam back to the boat. Mr. Chapelow remains missing.
The Santa Clara dam was inaugurated in 1969 and for a time was the largest dam in Portugal.
Covering approximately 520 square kilometres, the dam at its deepest points can reach close to 90 metres.
Commandant Batista had previously told The Portugal News that thick mud and a forest-like reservoir bed had made the search difficult.