Editing Dam (section)

===Modern era===
[[File:Ansel Adams - National Archives 79-AAB-01.jpg|thumb|The [[Hoover Dam]] by [[Ansel Adams]], 1942]]

The era of large dams was initiated with the construction of the [[Aswan Low Dam]] in Egypt in 1902, a gravity [[masonry dam|masonry]] [[buttress dam]] on the [[Nile River]]. Following their 1882 [[Battle of Tel el-Kebir|invasion and occupation of Egypt]], the British began construction in 1898. The project was designed by Sir [[William Willcocks]] and involved several eminent engineers of the time, including Sir [[Benjamin Baker (engineer)|Benjamin Baker]] and Sir [[Sir John Aird, 1st Baronet|John Aird]], whose firm, [[John Aird & Co.]], was the main contractor.<ref>{{cite web|url=http://www.collectstocks.com/egyptbond.html |title=Egyptian Irrigation Bond 1898 – Aswan Dam on Nile River |work=Scripophily |access-date=9 November 2015 |url-status=dead |archive-url=https://web.archive.org/web/20050513224447/http://www.collectstocks.com/egyptbond.html |archive-date=13 May 2005 }}</ref><ref>{{Citation |last=Roberts |first=Chalmers |date=December 1902 |title=Subduing the Nile |url=https://books.google.com/books?id=DoDNAAAAMAAJ&pg=PA2861 |journal=[[World's Work|The World's Work: A History of Our Time]] |volume=V |pages=2861–2870 |access-date=2009-07-10}}</ref> Capital and financing were furnished by [[Ernest Cassel]].<ref>[http://jewishencyclopedia.com/view.jsp?artid=142&letter=F&search=Finance Finance], ''[[Jewish Encyclopedia]]'', c.1906</ref> When initially constructed between 1899 and 1902, nothing of its scale had ever before been attempted;<ref>Frederic Courtland Penfield, [[s:Century Magazine/Volume 57/Issue 4/Harnessing the Nile|"Harnessing the Nile"]], ''[[The Century Magazine]]'', Vol. 57, No. 4 (February 1899)</ref> on completion, it was the largest masonry dam in the world.<ref>{{cite web|title=The First Aswan Dam |url=http://www.umich.edu/~kelseydb/Exhibits/AncientNubia/PhotoIntro.html |archive-url=https://web.archive.org/web/19970615204902/http://www.umich.edu/~kelseydb/Exhibits/AncientNubia/PhotoIntro.html |url-status=dead |archive-date=15 June 1997 |publisher=University of Michigan |access-date=2 January 2011 }}</ref>

The [[Hoover Dam]] is a massive concrete [[arch-gravity dam]], constructed in the [[Black Canyon of the Colorado|Black Canyon]] of the [[Colorado River]], on the border between the US states of [[Arizona]] and [[Nevada]] between 1931 and 1936 during the [[Great Depression]]. In 1928, Congress authorized the project to build a dam that would control floods, provide irrigation water and produce [[hydroelectric power]]. The winning bid to build the dam was submitted by a consortium called [[Six Companies, Inc.]] Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and the lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on 1 March 1936, more than two years ahead of schedule.<ref>{{cite book |last1=Interior |first1=United States Dept of the |title=The Hoover Dam Documents |date=1948 |publisher=U.S. Government Printing Office |page=79 |url=https://books.google.com/books?id=jTNAAAAAIAAJ&pg=PA79 |language=en}}</ref>

By 1997, there were an estimated 800,000 dams worldwide, some 40,000 of them over {{convert|15|m|abbr=on}} high.<ref>{{Cite journal |pmc=1470397 |last1=Joyce |first1=S. |title=Is it worth a dam? |date=October 1997 |journal=Environmental Health Perspectives |volume=105 |issue=10 |pages=1050–1055 |pmid=9349830 |doi=10.1289/ehp.971051050}}</ref> In 2014, scholars from the [[University of Oxford]] published a study of the cost of large dams – based on the largest existing dataset – documenting significant cost overruns for a majority of dams and questioning whether benefits typically offset costs for such dams.<ref>{{Cite journal |author1=Atif Ansar |author2=Bent Flyvbjerg |author3=Alexander Budzier |author4=Daniel Lunn |date=June 2014|title=Should we build more large dams? The actual costs of hydropower megaproject development|ssrn=2406852|journal=Energy Policy |volume=69 |pages=43–56|doi=10.1016/j.enpol.2013.10.069|arxiv=1409.0002 |bibcode=2014EnPol..69...43A |s2cid=55722535 }}</ref>