There's gold also at the bottom of balbina reservoir also. Which can be dredged with the tigerlynk......Property ownership in Brazil does not include rights to underground mineral deposits; the deposits belong to the government until ceded to private parties who register prospecting claims.
The submergence area also contains gold (Junk and de Mello, 1987) -- another mineral often mined from barges.http://philip.inpa.gov.br/publ_livres/Preprints/1989/BALBINA-ENG2.pdf