The Hoover (Boulder) Dam

Abstract

THE completion, just announced, of the great concrete structure originally known as the Boulder Dam, but afterwards officially designated the Hoover Dam, across the Colorado River in Black Canyon, which forms the boundary between the States of Arizona and Nevada, at a point about twenty-five miles south-east of Las Vegas, Nevada, marks the attainment of an advanced stage hi the execution of the notable Boulder Canyon Project, the Act for which was approved by the United States President in December 1928. The project in its entirety comprises not only the construction of a dam and the formation of an artificial lake, respectively the highest and the most capacious of their kind in the world, but also other incidental works involving an expenditure estimated at the time at 165 million dollars. The probable outlay is now given as 385 million dollars. The dam has a maximum height of about 730 ft., an extreme length of 1,180 ft., a crest width of 45 ft. and a bottom thickness of 650 ft. It contains about 4J million cubic yards of concrete, and will be the retaining wall of a reservoir having a length of 115 miles and a total cubic capacity of 30,500,000 acre-feet. It is designed to impound the flood water of the Colorado River for use in irrigation, and will serve to regulate the flow of that stream so as to improve its navigability, and protect the adjacent valleys from overflow, water shortage and silt accumulation. Irrigation and protection from inundation of valuable farm lands in Southern California are the primary and essential objects of the undertaking, but hydraulic turbines of exceptional calibre are also being installed to enable electric power to be generated, the revenues from which will fully recoup the outlay on the entire scheme, which, including a main irrigation canal, 80 miles in length, with an extension 130 miles long to adjacent valleys, is among the most remarkable instances of engineering enterprise in modern times.