SUBSURFACE WATERS 



In the foregoing we have discussed only surface waters. But in the last two years 

 increasing attention has been given to the possibilities of reclamation by utilizing subsurface 

 waters. Underground streams and lakes have been discovered at varying depths in many 

 valleys. One would imagine that a state with such little rainfall and where evaporation 

 is so great would be the last section of the country wherein bodies of underground water 

 might be expected. The contrary appears to be true. In about twenty different valleys 

 borings have been made, and in nearly all of these artesian flows have been encountered. 

 Nor has the depth been great, usually between 200 and 400 feet. Some wells have 

 found flows as shallow as 80 feet, and in only comparatively few instances has it been 

 necessary to go deeper than 500 feet. 



What is the origin of this artesian water? In most instances it may be satisfactorily 

 accounted for as coming from the percolation of melting snows in the porous strata of 

 contiguous mountain ranges and which is retained under pressure in the bordering valley 

 basins by an impervious stratum above. But in many instances artesian water exists as 

 abundantly in the regions of least rainfall. The most probable explanation of the latter 

 phenomenon is made clear when we examine cross-sections of the surface contour of the 

 State. From the region of greatest rainfall, including the extraordinary precipitation on 

 the eastern slopes of the Sierras, there is a general southeasterly slope or decrease of 

 surface elevation towards the Colorado River. It is well established that water has a 

 gravity movement or flow underground as well as on the surface wherever opportunity 

 exists. It is therefore quite probable that some portions, at least, of the underground waters 

 found in southern Nevada were originally precipitated upon mountains and in valleys 

 hundreds of miles distant. 



The economic feasibility of developing subsurface water for irrigation depends upon 

 three factors, namely: the cost of the well, the quantity of its flow, and the value of the 

 land for agricultural purpose when reclaimed. 



The last factor is the only one of the three which can be closely estimated in advance. 

 The character of the soil, climatic conditions and proximity to market and transportation 

 lines will enable a very accurate estimate to be made of the value of the land proposed to 

 be reclaimed when under cultivation. Suppose the land be covered with a thrifty growth 

 of black sagebrush, indicative of good soil, in northern and central Nevada such land 

 will bring in a gross average income from $25 to $40 per acre, if in alfalfa; $20 to $50 

 per acre if in wheat; $75 to $300 per acre if in potatoes, and proportionally in all other 

 crops. In the nine-months-long season of southern Nevada, where from eight to twelve tons 

 of alfalfa per acre are grown, and fruits, cantaloupes, and other intensive farm-crops 

 grow luxuriantly as well, the income of good land with water sufficient for its irrigation 

 will range anywhere from $50 to $400 per acre. 



Quantity of Water Required for Irrigation. 



The quantity of water required per acre in all instances will vary according to the 

 nature of the soil : whether porous and gravelly, or loamy and compact, and the proximity 

 to subsurface moisture. On ordinary soils and under average climatic conditions, it has 

 been determined that one-half an acre foot of water for each month of the irrigation 

 season is usually sufficient. But it is to be understood that soils and climatic conditions 

 vary, and while a less quantity might be ample on naturally moist and loamy soils, certain 

 deep gravelly soils will require considerably more. Also, that there is a variation in the 

 quantity of water required by different plants. The half-acre foot per month during 

 the irrigation season, however, is a safe rule in the majority of instances. This is equiva- 

 lent to a constant flow of 3.75 gallons per minute. 



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