 Even before Congress approved the Boulder Canyon Project , the Bureau of Reclamation was considering what kind of dam should be used . Officials eventually decided on a massive concrete arch @-@ gravity dam , the design of which was overseen by the Bureau 's chief design engineer John L. Savage . The monolithic dam would be thick at the bottom and thin near the top , and would present a convex face towards the water above the dam . The curving arch of the dam would transmit the water 's force into the abutments , in this case the rock walls of the canyon . The wedge @-@ shaped dam would be 660 ft ( 200 m ) thick at the bottom , narrowing to 45 ft ( 14 m ) at the top , leaving room for a highway connecting Nevada and Arizona . 
 Even before Congress approved the Boulder Canyon Project , the Bureau of Reclamation was considering what kind of dam should be used . Officials eventually decided on a massive concrete arch @-@ gravity dam , the design of which was overseen by the Bureau <a href='null_genetive' title='1'><mark>'s</mark></a>chief design engineer John L. Savage . The monolithic dam would be thick at the bottom and thin near the top , and would present a convex face towards the water above the dam . The curving arch of the dam would transmit the water <a href='null_genetive' title='2'><mark>'s</mark></a>force into the abutments , in this case the rock walls of the canyon . The wedge @-@ shaped dam would be 660 ft ( 200 m ) thick at the bottom , narrowing to 45 ft ( 14 m ) at the top , leaving room for a highway connecting Nevada and Arizona . 
Even before Congress approved da Boulder Canyon Project , tdaBureau of Reclamation was considering what kind of dam should be used . Officials eventually decided on a massive concrete arch @-@ gravity dam , the design of which was overseen by thdaureau  chief design engineer John L. Savage . Thedanolithic dam would be thick at the bottom and thin near the da , and would present a convex face towards the water above the dda. The curving arch of the dadaould transmit the water  force into the abudants , in this case the rockdalls of the canyoda The wedge @-@ shaped dam would be 660 ft ( 200 m ) thick at the bottomdanarrowing to 45 ft ( 14 m ) at the top , leavin room for a highway connecting Nevada and Arizona .