CONSTRUCTION work on the Hoover Dam on the Colorado River is progressing satisfactorily. This dam will be the largest in the world and will hold up more water than any other artificial reservoir. A description of it is given in Engineering of September 1. The Colorado River forms, for some distance, the boundary between the States of Arizona and Nevada and farther down it separates the former from California. The Boulder Canyon project is a Federal Government undertaking and as the Colorado watershed extends into Utah, Wyoming, Colorado and Mexico, seven States are affected. The water impounded in the dam will be used both for the production of power at the site and for irrigation purposes for lands at a lower level. The Imperial Valley in Southern California suffers from water shortage, from floods and from the silt they bring down. The great reservoir will enable the flow to be controlled and the avoidance of floods will prevent silt being carried down in troublesome quantities. It is estimated that silt is being deposited at present at the rate of 22 million cubic yards annually, the cost of clearing the canals amounting to more than a million dollars. The reservoir will cover an area of 145,000 acres and will have a capacity of 30,500,000 acre-feet. The scheme includes the construction of a new canal 80 miles long to the Imperial Valley. Unlike the present canal, none of it will be in Mexican territory. The hydro-electric power developed will be 620,000 horse power. The City of Los Angeles and the Southern California Edison Co. jointly will operate the power plant and distribute the energy in definite proportions to the city and various States and companies.
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