THE IRRIGATION AGE. 



79 



irrigation near 

 Grande 



and that no dam, 

 for diverting its 

 water at the head 

 of the Imperial 

 Canal is permitted 

 by the War De- 

 partment of the 

 United States, 

 which has charge 

 of the navigable 

 rivers. Without 

 such a dam the silt 

 in the canal soon 

 made it impossible 

 to divert water, ex- 

 cept during high 

 stages of the river. 



The first canal 

 intake had to be 

 abandoned, and a 

 new cut leading 

 into the Alamo be- 

 low the point, 



where the deposit of silt was deep, had to be made. 

 But the second intake soon shared the fate of the first, 

 and had to be abandoned for a third one. This third 

 intake was constructed without any safe headgate to 

 regulate the water, and in 1905 it washed out, until 

 the whole Colorado river passed through it into the 

 main canal, finding its way into Lake Imperial through 

 the Alamo river and New river. This disastrous over- 

 flow of the valley required two years to curb at a cost 

 of many millions of dollars, with large incidental losses, 

 which facts have been inadequately described in the 

 engineering publications, and about which engineers 

 have read more or less. 



After the break was closed, a concrete headgate 

 was constructed at the present site of the intake, and 

 with certain changes this improvement has continued 

 in use up to the present time. However, the silt diffi- 

 culty was not remedied by the present concrete head- 

 gate, as this only served to give better control of the 

 amount of water diverted, when the Colorado river 

 was high. The silt still continued to settle in the in- 

 take and in the canals. The Imperial Valley experi- 

 enced a water shortage, due to the fact that, as soon 

 as the Colorado reached a certain level, sufficient water 

 would no longer flow into the intake of the canal. 



Losses in crops amounting to hundreds of thou- 

 sands of dollars resulted in the years 1908, 1909 and 

 1910, during which time the level of the main canal 

 was gradually rising, on account of the silt deposited. 

 The canal was so wide, that it could not be cleaned out 

 by means of ordinary appliances, as in the case of 

 small irrigation canals and ditches. Those in charge 

 were unable to devise any method by which to remove 

 the silt, and on account of this and other difficulties, 

 the company became bankrupt, and was placed in the 

 hands of a court receiver. 



The culmination came in 1910, when less than one- 

 fourth of the needed amount of water could be di- 

 verted during the month of July. The receiver of the 

 company secured permission from the War Depart- 

 ment to construct a pile trestle in the Colorado above 

 the intake, for the purpose of forcing water into and 

 through the canal. 



Alamosa, Colo. 

 Railway. 



Courtesy Denver & Rio 



This was done 

 at heavy cost, by 

 driving piles and 

 dumping large 

 rocks into the bot- 

 tom of the river 

 above the trestle. 

 Thus temporary 

 relief was obtained 

 during the latter 

 part of 1910. The 

 receiver of the 

 company assumed 

 that it would be 

 necessary to repeat 

 this operation each 

 year, which would 

 incur an expense 

 far beyond the re- 

 c e i p t s obtained 

 from the sale of 

 water at 50 cents 

 per acre foot 

 delivered. 



Thereupon an order from the court to increase 

 the rate 60 per cent was sought by the receiver. This 

 was contested by the consumers under the water sys- 

 tem in a court action, on the ground that this method 

 of operating would not be successful, as the deposits 

 of silt would still continue to increase, until the chan- 

 nel and intake would be completely filled. 



During the trial of the case this was demonstrated 

 to the court, and another method, for ridding the in- 

 take and canal of silt, was submitted for the consid- 

 eration of the court by the representatives of the water 

 consumers. Before the conclusion of the trial, how- 

 ever, the receiver of the company became convinced 

 that this method should be tried, and a compromise 

 resulted, which permitted the water rate to remain at 

 the old rate of 50 cents per acre foot, while the new 

 method was being tried. 



The writer represented the water consumers as 

 expert in these proceedings and discussions, and was 

 selected to design the equipment planned for the pur- 

 pose of handling the silt. This plan was merely the 

 operation of suction dredges in the canal, whenever 

 necessary to pump the silt out to maintain the proper 

 level of the main canal. The case was compromised 

 and the suction dredge Imperial was constructed and 

 placed in operation in the spring of 1911. 



The result was to quickly eliminate the silt, which 

 had accumulated in the canal, and an abundant supply 

 of water was delivered during the entire year of 1911. 

 The dredge Imperial, after being constructed for the 

 water consumers, was first turned over to the receiver 

 and placed in operation on April 23, 1911, and from 

 that time to June, 1911, it pumped out a total of 122,- 

 105 cubic yards of solid material from the canal, lift- 

 ing it to a height of 35 feet at a cost of 4.8 cents per 

 cubic yard. 



By this time the water in the river had receded, 

 but the silt had been removed sufficiently to assure all 

 the water needed and, after the removal of more than 

 500,000 cubic yards during the summer of 1911. the in- 

 take and canal had been restored to their proper width 

 and original level and grade. 



Subsequently another small dredge was con- 



