Electricians Meet

Hutt News, Volume 19, Issue 10, 8 August 1945, Page 5

Electricians Meet

ADDRESSED BY POWER BOARD ENGINEER THE BOULDER DAM j Mr. C. H. Mitchell presided oyer a large gathering of the, Hutt Valley Branch of the N.Z. Institute of Electricians at the August meeting when, at the conclusion of general business, the Engineer-General Manager of the Hutt Valley Power Board .{Mr. L ; R. Robinson), gave an ad,t^re;sa on the Boulder Dam, .which Mr Jfrobiinson inspected during his recent tour of England, Sweden and U.S.A.' : "The main purpose for which the Boulder Dam was built," said Mr. Robinspn, "was flood control. The Colorado River is subject to very heavy floods, the maximum known b6ing approximately 300,000 cubic feet per second. It is interesting to compare this with the maximum flood recorded in the Hutt River which is 71,000 cubic feet per second.. Near the Mexican border the Colorado River runs on the edge of the Imperial Valley. The greater portion of this valley is below sea level. In 1904 the river burst its banks and flooded the whole of the Imperial Valley and greatly enlarged the Salton Sea, a salt lake. There has been a constant struggle by raising of levees to keep the water out of this valley. By the construction of the Boulder Dam the danger through flooding is practically eliminated. Another benefit of this dam is the improvement in the supply of water for irrigation purposes. The third benefit is water supply. As mentioned above the Boulder i Dam is within 300 miles of Los Angeles and the thickly populated area of the western coast of the United States. In and around Los Angeles, it is estimated that over three million people inhabit this area and before the advent of the Boulder Dam their water supply was derived from underground waters. These were being gradually depleted and salt water was infiltrating into the water bearing strata. By controlling the water and its purification an ample supply of clean water is obtained for this coastal area. The fourth benefit from the construction of the dam is the removal of the silt from the flood waters of the river. During times of flood the Colorado River carries an enormous amount of silt, it being estimated that some 15 per. cent of the volume is solid matter. The old Saying was

'the water was too thick to drink and too thin to plough.' The fifth benefit has been obtained, viz., the improvement to navigation ih the lower reaches of the river. Other incidental benefits are the provision of a very large lake some 224 square miles in area or about the same size as Lake Taupo, and which is attracting to it bird life of all kinds. Fishing is also being encouraged, particularly below the dam where the clarification of the water has made a very suitable stream for the introduction of rainbow trout. The whole, area has been declared a "wild life sanctuary" and no shooting pr hunting is permitted. However, visitors and sightseers are encouraged and since the area is within a day's motor dlriv© of several very large cities and towns, a very considerable number of tourists visit the area. In one year there were 600,000 visitors, most of whom would make a visit to the power station and dam. On one day they had 5,000 visitors at the power house and dam. It should be mentioned that whilst the major purpose for the building of the dam was flood control yet revenues derived from the sale of power will be the one which will ultimately pay for the cost of the construction of the works at Boulder Dam. ' There will ultimately be 17 generating units of a total capacity of 1,322,000 kilowatts and an output of 6,000,000,000 units per annum. To give a "yard stick" as the Americans say, the , installed capacity of the North Island system is 350,000 kilowatts and the output is about 1,600,000,000 units. At the time of my visit the installed capacity was slightly over 1,000,000 kilowatts." Mr. Robinson illustrated part of his address with a cinema film of the Boulder Dam under construc-j ' tion. ; >j