The Billings Reservoir (locally known as Represa Billings) is the largest reservoir in São Paulo, Brazil, covering a total of 127 km2. It is named after Asa White Kenney Billings, the American hydroelectric engineer who was instrumental in building it. The Portuguese word represa also means "dam". The reservoir supplies about 1.8 million people, and also is used for fishing and swimming. In recent years, there have been problems with wastewater and garbage such as plastic bottles, as well as problems associated with unapproved human settlement in the surrounding regions.