 When the water level is at its maximum of 175 metres ( 574 ft ) above sea level , which is 110 metres ( 361 ft ) higher than the river level downstream , the dam reservoir is on average about 660 kilometres ( 410 mi ) in length and 1 @.@ 12 kilometres ( 3 @,@ 700 ft ) in width . It contains 39 @.@ 3 km3 ( 31 @,@ 900 @,@ 000 acre · ft ) of water and has a total surface area of 1 @,@ 045 square kilometres ( 403 sq mi ) . On completion , the reservoir flooded a total area of 632 square kilometres ( 244 sq mi ) of land , compared to the 1 @,@ 350 square kilometres ( 520 sq mi ) of reservoir created by the Itaipu Dam . 
