Arauco is a department of La Rioja Province, Argentina. Population It had 723 inhabitants at the 2001 census, an increase of 16% since the last census in 1991, when it had 623 inhabitants. Settlements Aimogasta Arauco Bañado de los Pantanos Estación Mazán Machigasta Termas de Santa Teresita Udpinango Villa Mazán San Antonio Departments of La Rioja Province, Argentina