Keywords: HansenBasReliefHooverDam.jpg en wikipedia 2011 March 23 Oskar J W Hansen's bas-relief on Hoover Dam's Nevada elevator depicting the benefits of the dam flood control navigation irrigation water storage and power http //www usbr gov/lc/hooverdam/images/nvtower jpg date of upload Bureau of Reclamation PD-USGov Original upload log en wikipedia NortyNort CommonsHelper page en wikipedia Hansenbasrelief jpg 2010-06-22 19 59 NortyNort 82×300× 8776 bytes <nowiki> Oskar J W Hansen's bas-relief on Hoover Dam's Nevada elevator http //www usbr gov/lc/hooverdam/images/nvtower jpg ~~~~~ date of upload Bureau of Reclamation </nowiki> Hoover Dam sculpture relief |