The reservoir is supplied by the River Guarapiranga and other smaller rivers and brooks, traversing areas of the cities of São Paulo,
Itapecerica da Serra, and
Embu-Guaçu. It was constructed originally to attend the necessities of the production of electrical energy in the Parnaíba
Hydroelectric generating plant. It is currently utilized for the water supply for the
Greater São Paulo by the
Companhia de Saneamento Basico do Estado de São Paulo (SABESP), a Brazilian state owned utility that provides water and sewage services. Guarapiranga is also utilized as a flood control mechanism and as a place of leisure. There are artificial beaches and
marinas in the reservoir's peripheral areas. ==Current use==