 Since about 1900 , the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods , provide irrigation water and produce hydroelectric power . In 1928 , Congress authorized the project . The winning bid to build the dam was submitted by a consortium called Six Companies , Inc . , which began construction on the dam in early 1931 . Such a large concrete structure had never been built before , and some of the techniques were unproven . The torrid summer weather and lack of facilities near the site also presented difficulties . Nevertheless , Six Companies turned over the dam to the federal government on March 1 , 1936 , more than two years ahead of schedule . 
 Since about 1900 , the Black Canyon and nearby Boulder Canyon <a href='been_done' title='1'><mark>had</mark></a> been investigated for their potential to support a dam <a href='null_relcl' title='2'><mark>that</mark></a>would control floods , provide irrigation water and produce hydroelectric power . In 1928 , Congress authorized the project . The winning bid to build the dam was submitted by a consortium called Six Companies , Inc . , which began construction on the dam in early 1931 . Such a large concrete structure <a href='been_done' title='3'><mark>had</mark></a> never been built before , and some of the techniques <a href='uninflect' title='4'><mark>were</mark></a> unproven . The torrid summer weather and lack of facilities near the site also presented difficulties . Nevertheless , Six Companies turned over the dam to the federal government on March 1 , 1936 , more than two years ahead of schedule . 
Since about 1900 , da Black Canyon and nearby Boulder Canyon done been investigated for their potential to support a dam would control floods , provide irrigation water and produce hydroelectric power . In 1928 , Congress authorized tdaproject . The winnin bid to build the dam was submitted by a consortium called Six Companies , Inc . , which began construction on thdaam in early 1931 . Such a large concrete structure done never been built before , and sum of the techniques was unproven . The torrid summer weather and lack of facilities near the site also presented difficulties . Nevertheless , Six Companies turned ova the dam to the federal government on March 1 , 1936 , more den two years ahead of schedule .