44 



THE IRRIGATION AGE. 



than formerly. Few farmers have cared to go to the 

 expense of planting a crop or orchard, and cultivate it 

 perhaps for years with the risk of a possible loss of the 

 entire crop, from shortage of water through the summer 

 months. 



SOIL STRATA AND UNDERFLOW IN THE RIO GUANDE 

 VALLEY. 



No very definite statements can be made regard- 

 ing the soil strata of the Rio Grande Valley in the 

 absence of a systematic investigation of the question. 

 We can only be guided by the incomplete data secured 

 on this important question from the little work that 

 has been done up and down the valley. From this it 

 becomes apparent that conditions do not vary much 

 throughout the length of the Rio Grande Valley in New 

 Mexico which is cultivated. In a general way, the 

 valley consists of made lands, that is to say, sand, gravel 

 and sediments that have been washed down and de- 

 posited in the valley through past ages. What the 

 depth of this deposit is, it is impossible to state with 

 any degree of accuracy but it is undoubtedly very great 

 in some parts. 



SOIL STRATA. 



The various strata found throughout the valley 

 consist of layers of soil,, sand and gravel, of varying 

 degrees of coarseness, with occasional layers of hardpan 

 or clay. Sand evidently forms the greater part of the 

 strata in the valley and in many parts extends to the 

 surface, although usually covered by a layer of sedi- 

 ment and rich soil varying in thickness from a few 

 inches to many feet. It seems to be generally true 

 that most of the valley is underlaid at a reasonable 

 depth with gravel beds sufficiently thick to procure from 

 them by means of slotted strainers an ample water sup- 

 ply. In the Mesilla Valley a gravel bed is usually 

 found at from twenty to eighty feet in depth although 

 there is no certainty as to the depth at which it will be 

 found or the thickness of the stratum. 



Along the foot hills of the valley the question of 

 underlying strata is a much more uncertain one, but 

 in the valley proper we know that large quantities of 

 sand and varying thicknesses of gravel will be met with. 

 Only more extensive exploitation will demonstrate what 

 may reasonably be expected to be encountered in sink- 

 ing a well. 



UNDERFLOW. 



When it comes to the matter of underflow the ques- 

 tion is no uncertain one. Throughout the whole length 

 of the valley proper, water will be found at a depth of 

 from four or five feet to twenty or thirty feet, depend- 

 ing upon the height of the ground above the level of the 

 river bed. This water appears to be generally of a 

 good and fairly uniform quality throughout the valley, 

 though near to the foot hills the quality is an uncertain 

 thing. In the matter of quantity, it seems to be more 

 a matter of providing means for making the water 

 available than any question as to the underflow. Some 

 New Mexico farmers using gauze covered strainers in a 

 small size quite unsuited to the securing of large quan- 

 tities of water, have met with very unsatisfactory re- 

 sults, as the strainers have filled up and the flow 

 greatly diminished; and they have come to the erro- 

 neous conclusion that the water was not there. Where 

 suitable strainers have been placed in a gravel bed 

 which allows the free passage of the water to the well 

 there has been no complaint of the amount of the 

 supply. 



The whole valley appears to be underlaid with 

 water. Whether this is an immense reservoir or a 

 river flowing in any direction is not certain, arguments 

 being advanced to support both theories. We do know, 

 however, that the amount of water below is enormous 

 and amply sufficient to meet all reasonable needs. It is 

 probably safe to say that a sufficient quantity of water 

 exists under every acre of irrigable land in the Rio 

 Grande Valley which if raised to the surface would 

 irrigate it ; and there seems to be no reasonable ground 

 for believing that this supply will cease to exist. 

 WELLS. 



For convenience, wells may be classified under two 

 heads, viz., open wells and pipe wells. The latter are 

 sometimes termed driven wells. For the purpose of this 

 bulletin, an open well is defined as one in which no 

 part of the well is utilized as an aid either in lifting or 

 directing the water to the surface of the ground. A 

 pipe well, on the other hand, is one to which the pump 

 is directly attached to the well itself ; it therefore may 

 be said to form a part of, or a necessary adjunct to, 

 the pumping machinery. Some wells are not, strictly 



TIMBER DERRICK USED IN SINKING STATION WELL. 



speaking, under either of these heads, but for the pres- 

 ent discussion such may be ignored, since all wells re- 

 ferred to in this bulletin come in one or the other of 

 these classes. 



OPEN WELLS. 



Everything being equal, that is, in capacity, cost, 

 ease of sinking, and the life of the well, the open well 

 is the better. Under the conditions existing in the 

 Rio Grande Valley and other similar areas, the open 

 well, however, is a difficult and costly undertaking, and 

 until improved and less expensive methods are devised, 

 the first cost of an open well will preclude its general 

 adoption. By referring to the tables shown in this 

 bulletin, it will be seen that the experimental six-inch 

 station well, costing $150, has a capacity equal to or 

 greater than that of open wells, costing several thou- 

 sands of dollars. A number of open wells, costing 

 considerable more than this six-inch pipe well, have a 

 less capacity. Nevertheless, the open well or its equiva- 

 lent, with its accompanying minimum cost for lifting 

 the water to the surface of the ground, is the ideal that 

 should be constantly borne in mind. 



METHOD OF SINKING. 



A large area of the irrigable land in New Mexico 

 is underlaid with sand, and the great difficulty in sink- 



