 In the following years , the Bureau of Reclamation ( BOR ) , known as the Reclamation Service at the time , also considered the Lower Colorado as the site for a dam . Service chief Arthur Powell Davis proposed using dynamite to collapse the walls of Boulder Canyon , 20 miles ( 32 km ) north of the eventual dam site , into the river . The river would carry off the smaller pieces of debris , and a dam would be built incorporating the remaining rubble . In 1922 , after considering it for several years , the Reclamation Service finally rejected the proposal , citing doubts about the unproven technique and questions as to whether it would in fact save money . 
