Arizona republican., 1902-12-26
The | n ierground Waters.

When Engineer DaNlS Ol thS Chi'SN States geological survey makes ms re- port on the underground waters or the Salt River valley much additional hght will be thrown on a very interesting subject. It is not alone in this valley that the survey is making inVestga- tious as to the volume and rapidity or flow of the water beneath the surface
 The work in this field has already GOV cred a wide area, and a paper just published by the survey, entitled "Tne Motion of Underground Waters IS or timely interest in view of the work nc" being carried on here under the super
 yision of Mir. Davis. Prof. Charles s. Schlicter, the author of the paper re- ferred to-; undertakes to estimate the total volume of water within the crust of the earth, and he presents figures So large that the mind cannot grasp them: However, it is when he deals with the practical question of utilizing the un- derfiow that his conclusions have par ticuIar interest for the irrigated re- giens.
 The rate of movement of the under flow has been the subject of long and careful investigation. To determine this interesting question measure ments have been made in the river gravels of streams whose surface flows have ceased, and from such measure ments more or less trustworthy results have been obtained. One of the most accurate and interesting of these is q series of experiments conducted by Professor Slichter. along the valley of the Arkansas river in western Kan sas. The method is an electrical one. A double row of inch and a quarter drive-wells is sunk across the channel of the river whose underfiow is to be tested. The upstream wells are then charged with a strong electrolyte. which dissolves and passes down the stream with the moving water. The passage of the electrolyte toward the lower we'll is shown by the gradual movement of the needle of an electrical instrument, and the final arrival at the we'll is shown by a sudden and exceedingly interesting to watch the gradual movement of the water, which can be traced from the beginning O. the experiment in this indirect way By this method the rate of flow 10 feet below the bed of the Arkansas river was found to be 21a feet per day. Other experiments in the beds of the Hondc and San Gabriel rivers in southern California, gave rates of 31z, 4, 51a and feet per day.
 The knowledge of the underfow that exists beneath the gravel of all river valleys has been taken advantage of in arid sections of the west, where the running dry of streams deprives irriga- tors of their water supply. By exca- vating to bed rock in river gravels and building an impervious barrier across the channel, these underground waters are saved in sufficient quantities to be of great value to the farmer. A mo- table subsurface dam of this kind has been constructed on the Pacoima creek. California, to furnish water for irrigation and domestic use.
 Deep zones of flow are a most inn portant feature of the movements or underground waters, and open up an interesting field for investigation. The wonderful artesian basin of North Da- kota and South Dakota, which has proved such an important factor In the economic development of these states, forms one of the illustrations used by Professor Slichter in the explanation of deep-seated underfows. A cross section of this part of the country clearly shows the interesting fact thal the water which comes to the surface in the gushing wells of the Dakotas travels underground all the way from the Black Hills and Rocky mountain | slopes, in the bearing strata | known as the Dakota sandstones | Another illustration of extensive | basins due to deep underground flows | is found in Wisconsin, where an ex- | tensive area of water bearing rocks, | nearly 1000 feet thick, conducts water of singular purity under large areas of | the state.
 IL must be borne in mind that there | is a limit to the amount of water whIca can be drawn from an artesian basin. Son that there is no such thing as an Name austible underground supply | ScriEradual failure of the wells which
 fr@sy the city of Denver clearly illus
 ,I1s this fact. So great a demano .hurcF ade upon this basin between the
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