HooverDam, was built in the Black Canyon of the Colorado River, during the depressionera of the twentieth century.
The dam’s construction was authorized by The Boulder Canyon Project Act of 1928. Situated along the border between the United States’ southwesternstates of Nevada and Arizona, its construction began in 1931, during PresidentHerbert Hoover’s tenure and was completed in 1936 during President Franklin D.Roosevelt ‘s first term. It was thefirst mega-dam ever built. Interestingly, the United States Departmentof the Interior’s Bureau of Reclamation, still declares that: “HooverDam was the first of the large reclamation projects along the ColoradoRiver.” Reclaim or reclamation are defined as “to bring (waste land or land formerly underwater) under cultivation.” 
Native peoples a/k/a American Indians (The Las Vegas Paiute Tribe) have lived in theLas Vegas region for over 10,000 years.
Indeed, scientists have found pictographs, petroglyphs, baskets, as well as other corroborating evidence in varioussites, including the Gypsum Cave, a five room cavern, about twelve miles eastof Las Vegas. Artifacts linked to early human habitation,were discovered in the cave, evidencing the area’s ecosystem and the types of livesthat these people lived. Numerous native tribes, including, the Hopi,Mojave, and Paiute have lived in the region for over a millennia. They taughtthemselves how to both survive, and to live in the desert and along theColorado River. Some of the treasures thatexisted pre-inundation. and probably a number of Indian burial mounds, liebeneath the dam and its reservoir, Lake Mead.
But, for the Hoover Dam, America’s World War II efforts, would have been devoid of the “electricalpower it was providing to southern California, home of some of the nation’sbiggest defense plants, where planes and tanks and other armaments would bebuilt on a round-the-clock basis once America’s mighty industrial machine wentto war.”
Moreover, Hoover Dam’s construction came,as it did, during the Great Depression during a time of pervasive destitutionand widespread unemployment. This colossal endeavor “not onlyprovided jobs to thousands of unemployed men but offered some of the mostcomplex engineering challenges ever tackled. Perhaps as important, it assertedAmerica’s ability to overcome extreme adversity with technical ingenuity,physical prowess, and unwavering resolve.” Indeed,[t]he project’s goal: Build a huge dam— the largest ever built— across the Colorado River on the Nevada-Arizona border to harness the power and riches of the mighty river. Completed in 1936, Hoover Dam,  through the generation of electricity and the orderly dispersal of its waters, fueled the incredible growth of southern California— its large cities, its industrial base, its massive agricultural industry— and created Lake Mead, the world’s largest man-made reservoir.
Indeed, given the advent World War II, the country’s demand for electricity, primarily western hydro-generated power, skyrocketed. Moreover, at the outbreak of the war, the three Axis Nations (Germany, Italy and Japan) possessed much more available electric power than the U.S. In 1942, the department of interior initiated a “war program”, in which it recognized that its generation of power for the war, will demand a “war budget of $56 billion will require 154 billion kilowatt hours (kWh) of electric energy annually for the manufacture of airplanes, tanks, guns, warships, and fighting material, and to equip and serve the men of the Army, Navy, and Marine Corps.”
every dollar expended for use by the wartime industrial-complex, approximately,
2-3/4 kWh hours of electric power were required.
That demand outstripped the overall production
capacity of the entirety of the then-existing electric utilities in the U.S. “In 1942, 8.5 billion kWh of electric power
was required to produce enough aluminum to meet the President’s goal of 60,000
 Act of Dec. 21, 1928, c. 42, 45 Stat. 1057, codified at 43 U.S.C. §§ 617 et seq. On the Boulder Canyon Project Act of 1928, see Itzchak E. Kornfeld, Transboundary Water Disputes: State Conflict and the Assessment of their Adjudication (Cambridge Univ. Press 2019) at 197 – 210.
 “Although there is no universal definition of what qualifies as a mega dam, as a general rule they are large structures over 15 metres in height generating over 400 megawatts of power on average.” Emanuele Bompan, et al., Water and Power: Mega-Dams, Mega-Damage? SciDevNet (Mar. 22, 2017), https://www.scidev.net/global/water/data-visualisation/water-power-mega-dams-mega-damage.html.
 United States Department of the Interior’s Bureau of Reclamation, Hoover Dam: Learning Packet (1999), at 18 https://www.usbr.gov/lc/hooverdam/educate/hoovered.pdf
 See definition of Reclaim at https://www.google.com/search?q=definition+ of+ reclaim&oq= definition+of+reclaim&aqs=chrome..69i57j69i60.30996j0j4 &sourceid= chrome&ie=UTF-8.
 Amy Gilreath, Gypsum Cave, O·n·e nevada encyclopedia (Jan.4, 2011), http://www.onlinenevada.org/articles/gypsum-cave.
 Ibid. Dates of wooden dart fragments in the cave have yielded radiocarbon dates between 3,300-4,250 years before present (BP). However, the oldest item found, a woven basket, has been dated at 9,280 years BP.
 Christine Pfaff, Safeguarding Hoover Dam during World War II, 35 Prologue Mag. No. 2 (Summer 2003), https://www.archives.gov/publications/prologue/2003/summer/hoover-dam-1.html.
 “At the height of the Depression in 1933, 24.9% of the total work force or 12,830,000 [i.e., 3,207,500 individuals] people was unemployed. Although farmers technically were not counted among the unemployed, drastic drops in farm commodity prices resulted in farmers losing their lands and homes to foreclosure.” Franklin D. Roosevelt Presidential Library and Museum, Great Depression Facts, (2016), https://www.fdrlibrary.org/great-depression-facts.
 Pfaff, ibid.
 United States Department of the Interior, Bureau of Reclamation, RECLAMATION, Lower Colorado Region, A Century of Cooperation, Reclamation and Arizona, World War II – Reclamation, Arizona, and Hoover Dam (2003), at Hoover Dam’s Importance to the War Effort https://www.usbr.gov/lc/phoenix/AZ100/1940/topstory.html.
 Course Hero, A 4500 kw Powerplant was Constructed in 1909 Five (2019), https://www.coursehero.com/file/p1n88bv/A-4500-kW-powerplant-was-constructed-and-in-1909-five-generators-were-in.