Editing Hoover Dam (section)

=== Planning and agreements ===

In 1922, the Reclamation Service presented a report calling for the development of a dam on the Colorado River for flood control and electric power generation. The report was principally authored by Davis and was called the Fall-Davis report after Interior Secretary [[Albert Fall]]. The Fall-Davis report cited use of the Colorado River as a federal concern because the river's basin covered several states, and the river eventually entered Mexico.{{sfn|Hiltzik|2010|p=67}} Though the Fall-Davis report called for a dam "at or near Boulder Canyon", the Reclamation Service (which was renamed the Bureau of Reclamation the following year) found that canyon unsuitable.{{sfn|Hiltzik|2010|p=68}} One potential site at Boulder Canyon was bisected by a [[geologic fault]]; two others were so narrow there was no space for a construction camp at the bottom of the canyon{{sfn|Hiltzik|2010|p=68}} or for a spillway. The Service investigated Black Canyon and found it ideal; a railway could be laid from the railhead in Las Vegas to the top of the dam site.{{sfn|Dunar|McBride|2001|p=6}} Despite the site change, the dam project was referred to as the "Boulder Canyon Project".{{sfn|Stevens|1988|pp=26–27}}
[[File:Boulder damsite sketch.jpg|thumb|left|Sketch of the proposed dam site and reservoir, {{circa|1921}}]]
With little guidance on water allocation from the [[Supreme Court of the United States|Supreme Court]], proponents of the dam feared endless litigation. Delph Carpenter, a Colorado attorney, proposed that the seven states which fell within the river's basin (California, Nevada, Arizona, Utah, New Mexico, Colorado and Wyoming) form an [[interstate compact]], with the approval of Congress.<ref>{{Cite web|date=2011-12-09|title=Sharing Colorado River Water: History, Public Policy and the Colorado River Compact|url=https://wrrc.arizona.edu/publications/arroyo-newsletter/sharing-colorado-river-water-history-public-policy-and-colorado-river|access-date=2020-08-01|website=wrrc.arizona.edu|language=en}}</ref> Such compacts were authorized by [[Article I of the United States Constitution]] but had never been concluded among more than two states. In 1922, representatives of seven states met with then-[[United States Secretary of Commerce|Secretary of Commerce]] [[Herbert Hoover]].{{sfn|Hiltzik|2010|pp=73–79}} Initial talks produced no result, but when the Supreme Court handed down the ''[[Wyoming v. Colorado]]'' decision undermining the claims of the upstream states, they became anxious to reach an agreement. The resulting [[Colorado River Compact]] was signed on November 24, 1922.{{sfn|Hiltzik|2010|pp=81–87}}

Legislation to authorize the dam was introduced repeatedly by two California Republicans, Representative [[Phil Swing]] and Senator [[Hiram Johnson]], but representatives from other parts of the country considered the project as hugely expensive and one that would mostly benefit California. The [[1927 Mississippi flood]] made Midwestern and Southern congressmen and senators more sympathetic toward the dam project. On March 12, 1928, the failure of the [[St. Francis Dam]], constructed by the city of Los Angeles, caused a disastrous flood that killed up to 600 people. As that dam was a curved-gravity type,<ref>{{Cite journal |last= Rogers |first= J. David |date= September 28, 2007 |url= http://web.mst.edu/~rogersda/st_francis_dam/index.htm |title= Impacts of the 1928 St. Francis Dam Failure on Geology, Civil Engineering, and America |journal= 2007 Annual Meeting Association of Environmental and Engineering Geologists |publisher= Missouri University of Science & Technology |access-date= September 29, 2013 |archive-url= https://web.archive.org/web/20131211184431/http://web.mst.edu/~rogersda/st_francis_dam/index.htm |archive-date= December 11, 2013 |url-status= live }}</ref> similar in design to the arch-gravity as was proposed for the Black Canyon dam, opponents claimed that the Black Canyon dam's safety could not be guaranteed. Congress authorized a board of engineers to review plans for the proposed dam. The Colorado River Board found the project feasible, but warned that should the dam fail, every downstream Colorado River community would be destroyed, and that the river might change course and empty into the Salton Sea. The Board cautioned: "To avoid such possibilities, the proposed dam should be constructed on conservative if not ultra-conservative lines."{{sfn|Rogers|2010}}

On December 21, 1928, [[Calvin Coolidge|President Coolidge]] signed the bill authorizing the dam.{{sfn|Hiltzik|2010|p=118}} The Boulder Canyon Project Act<ref>{{USStatute|70|642|45|1057|1928|12|21|HR|5773}}</ref> appropriated $165&nbsp;million for the project along with the downstream [[Imperial Dam]] and [[All-American Canal]], a replacement for Beatty's canal entirely on the U.S. side of the border.{{sfn|Stevens|1988|p=27}} It also permitted the compact to go into effect when at least six of the seven states approved it. This occurred on March 6, 1929, with Utah's ratification; Arizona did not approve it until 1944.{{sfn|Hiltzik|2010|p=120}}