 In the latter half of 1936 , water levels in Lake Mead were high enough to permit power generation , and the first three <unk> <unk> built Francis turbine @-@ generators , all on the Nevada side , began operating . In March 1937 , one more Nevada generator went online and the first Arizona generator by August . By September 1939 , four more generators were operating , and the dam 's power plant became the largest <unk> facility in the world . The final generator was not placed in service until 1961 , bringing the maximum generating capacity to 1 @,@ 345 megawatts at the time . Original plans called for 16 large generators , eight on each side of the river , but two smaller generators were installed instead of one large one on the Arizona side for a total of 17 . The smaller generators were used to serve smaller communities at a time when the output of each generator was dedicated to a single municipality , before the dam 's total power output was placed on the grid and made <unk> <unk> . The present contracts for the sale of electricity <unk> in 2017 . 
