The Arizona sentinel., 1908-12-30
YUMA IRRIGATION PROJECT.
IContinued from Page One.

COntlnue0 rom HaSe Onc.
 the dam on its downstream side iscoveredwith concrete pavement IS inches thick. On the down stream side of the lower wall is an ample apron of derrick stone so placed as to protect the struc- ture from auy tendency of the river to back-cut. The dam has a maximum width of about 250 feet and maximum height of 19 feet. At the present time the structure is about 65 per cent complete, there being some seven hundred feet in mid stream to finish and some work around the shore ends. All signs indicate that this winter will be e favor able one for our work and it is expected that the coming spring will mark the completion of the dam.
 REMOVAL OF SILT.
 The Colorado is a silt t-bearing stream of considerable magni- sude, carrying at times nearly three per cent in weight of light sandy material which rapidly which rapidly fills the heads of canals that are constructed with cut due regard to this contin- gency. Many canals in this vii einity, constructed under the guidance of private enterprise, have become physical and tlnan- eial wrecks owing to failure to properly provide for the sitting action of the river. This feature was carefully considered in the designs of the Reclamation Ser vice and elaborate arrangements are being made to insure free dom from silt deposits in our canals. The dam will create a lake about tea miles in length and of considerable width, in which there will be more or less deposit as the water approaches ahe dam. Leading from this (1ake to the canals at each end of the dam are sluiceways about one thousand feet in length, so proportionel that the water must pass through them with veloc. ity appreximating one foot per second, so that the main body of the silt will be dropped. The lower ends of these sluiceways are closed by enormous gates which will he opened periodically to allow the accumulated silt to be Sluiced on into the river be low the dam. The regulators controlling the canal supply are placed on the land side of the sluiceways slightly above the gates and are so arranged tha' only the top of the water in the sluiceway, being that which is most thoroughly clarified, is al lowed to enter the canal. As ( further precaution the first hall mile of the main canal is con structed of ample section to give velocity not exceeding one anC One-half feet per second, which will provide for the Settlemen of any undesirable material tha may pass the regulators. At thu lower end of this half mile, gate are provided for sluicing the sil in the canal above on into tn, river below. While this compre sive method of handling the sil problem will remove most of tn, suspended matter from the wate before it begins its journey t, cultivated lands below, it doe not take out those fertilizing ele mentS for which the Colorad water is so justly famed.
 THE MAIN CANAL.
 This structure leaves Lagun Dam on the California side anr for the entire distance to Yum passes through the Yuma Indial reservation. About + miles be low the dam is a favorable sit for a power house and condition and conditions are such that
 drop can here be made in tn canal from which electrical ener gy may be developed. Whe the future extension to the mes land is made the power here ere