Engineering Wonders of the World
Volume III

THE COLORADO RIVER CLOSURE. 115 intersecting the Imperial Valley in all direc- tions. The valley proved to be marvellously fertile, its soil producing a crop of alfalfa grass in six weeks. Settlers were attracted, and soon 12,000 persons were cultivating 2,000 farms in a region hitherto practically uninhabited by man. The waters were turned into the valley in Fig. 1.—SKETCH MAP TO SHOVZ THE LOCATIONS OF THE FIRST FIVE ATTEMPTS MADE TO CLOSE THE BREACH IN THE RIVER BANK. The course of the water during these operations is shown by the shading. The Figs, indicate:—1. First attempt, January 1905. 2. Second attempt, May 1905 to Juno 1905. 3. Third attempt, July and August 1905. 4. Fourth attempt, October 13 to November 29, 1905. 5. Fifth attempt, January 8 to October 11, 1906. The small canal, x, cut to increase the volume of irrigation water, was the cause of all the trouble. June 1901. Unfortunately, in their haste to complete their contract up to time, the engi- neers placed the floor of the headgate five feet above the level originally planned, and too high to pass water at the river’s lowest state. As a result the connecting canal silted up, and though dredgers were kept at work, the water delivered did not meet the needs of the many settlers. • To remedy matters, a ditch (marked x in Fig. 1) was cut—late in 1904—from the channel to the Colorado direct, about four miles below the original headgate. This ditch, 50 feet wide, had a fall of 1| feet in its 3,300 feet ; but déspite its ample di- mensions it soon became obstructed. It was cleared, only to close again. A third time the engineers opened it, and then occurred a flood which widened and deepened the ditch until the Colorado chose an easier way down into the Sink, leaving its bed dry below the breach and its old estuary waterless. This unexpected mishap portended terrific consequences. Unless checked, the river would fill up the depression to sea-level, and create the largest body of water in the United States. To stave off ruin from the settlers, it was im- perative to turn the river back into its old bed—a task far more difficult than was at first anticipated, as the story will show. To understand the operations of the next two years, the reader should refer to the two Fig. 2.—MAP SHOWING THE POSITION OF OPERATIONS DURING THE SIXTH AND SEVENTH ATTEMPTS TO CLOSE THE CREVASSE. sketch maps, Figs. 1 and 2, which show by numerals the lo- calities of the seven attempts made to close the breach. The first attempt, begun in January 1905, consisted of driving down piles 3 feet apart across the entrance to the crevasse cut by the stream, and filling in the spaces with brushwood and bags of sand. Th© supply of sacks failed be- A fore the work had been com- pleted, and during the wait for more the half- finished dam gave way. This made the engi-