<prompt> Translate the following text to EnglishUjenzi wa bwawa la Hoover walioitwa Boulder Dam, baadaye wakaliita kwa jina la rais aliyeruhusu mradi huo ulianza mwaka 1931 katika bonde la maji lililo kilomita 45 kusini-mashariki mwa Las Vegas.  <response>: Construction on Hoover Dam originally Boulder Dam, subsequently renamed for the president who authorized the project began in 1931 in a canyon 45 miles 72 km southeast of Las Vegas. 