THE IRRIGATION AGE. 



1017 



in order that the combined flow may be used for irrigation 

 or stored in a reservoir, they may be so placed if they are 

 bored to different flows and all but the lower flow is cased 

 off from the deeper well. In this way there will be no in- 

 terference. Instead of sinking two separate wells of differ- 

 ent depths, the same effect may be gained by reducing the 

 bore of a large well and continuing it to lower flows, the 

 water from the deeper flows coming up through the smaller 

 inside casing. However, separate wells will in general be 

 preferable, owing to the difficulty of cleaning and repairing 

 multiple wells. 



By far the greater number of wells, as will be seen 

 later, are cased only to the first solid clay, a depth varying 

 ordinarily from 10 to 40 or 50 feet. The bore is continued 

 through the various water-bearing beds until a suitable flow 

 is reached. As long as this deeper flow of higher pressure 

 continues the water from the upper water beds will not come 

 into the bore and there will be no mingling of the different 

 flows; but if the well is plugged or is choked near the top, 

 the lower flows, which are under greater pressure, will 

 spread out in the upper beds that are under less pressure, 

 so that the pressure tends to be equalized in the upper and 

 lower flows, and as a result the pressure and consequently 

 the yield of the lower flows are weakened. This process 

 has taken place to such an extent toward the center of the 

 town of Monte Vista that the yield from the various flows is 

 identical, and likewise the temperature. 



Sudden Failure of Wells. In almost all cases sudden 

 failure is due to the caving away of the clay walls of the 

 well. In a well that is not cased the caving in of the clay 

 anywhere along the bore may shut off the water from below 

 the caved place. In a well that is cased to the sand bed 

 furnishing the flow ordinarly there is a rather large cavity 

 in the sand at the bottom of the casing, resulting from the 

 sand being carried up and thrown out of the well. Occa- 

 sionally large pieces of the clay bed above may tumble into 

 this cavity and clog the bottom of the casing. In the vicinity 

 of Hooper, and northward on the Kinney ranch, the practice 

 is to let the 1-inch pipe that serves as a drill rod remain in 

 the well after completion. This rod, projecting downward 

 below the casing and into the cavity at the base of the 

 well, ordinarily prevents the complete closure of the well 

 by any falling chunks of clay. 



Irregularities in Flows from the Same Aquifer. Ad- 

 jacent wells that strike the same water bed may have very 

 different flows. These irregularities are probably to be ex- 

 plained by the irregularities in thickness or porosi*y of the 

 water-bearing bed. The rate at which water passes through 

 sand varies with the size of the sand particles, being greater 

 for the coarser varieties. For this reason the gravel flow 

 obtained in certain parts of the valley is a very free, strong 

 flow. Local variations in the same bed of sand therefore 

 exert a very definite effect upon the quantity of flow. 



As the rate of flow through sand of a given size is 

 fixed, the volume of flow from any bed of sand of that size 

 depends on the thickness of the bed. It is not to be pre- 

 sumed that the beds of sand in the valley, though known 

 to be of great extent and persistence, are of the same thick- 

 ness throughout. Any formation built up more or less in 

 delta form, as are the deposits of the Rio Grande alluvial 

 fan, must of necessity differ in thickness from place to 

 place, and such differences are undoubtedly ample to account 

 for any variations in flow from the same bed. 

 Variation in Temperature. 



The vertical range in temperature observed in the wells 

 of the valley is from a minimum of 45 in shallow wells to 

 a maximum of 75 for the Bucher well at Alamosa. The 

 increase of temperature with depth is very regular ; estimated 

 from the deep cased wells near Alamosa it is 1 for 28J^ 

 feet. 



The minimum temperature is found in wells on the low 

 ground near the Rio Grande north of Monte Vista. South- 

 ward along the Gunbarrel road and southeastward along the 

 flowing-well limit to the vicinity of La Jara the shallowest 

 wells have temperatures of about 46. Southeast of La Jara 

 along Conejos river the shallowest wells have temperatures 

 of 50 to 52. North of Monte Vista along the Gunbarrel 

 road the temperature of the first flow likewise increases 

 and in the vicinity of Center it is about 51 or 52. Further 

 north, in the Veteran neighborhood, the temperature is lower 

 again, 46 and 47 in wells reaching the first flows. These 

 temperatures continue to the vicinity of Russell springs, 



but from there to Swede Corners, 2J/2 miles north, there is 

 an increase in temperature of 10 in wells of practically the 

 same depth. On the east side of the basin the temperatures 

 are very regular and such as would normally be expected, 

 that is to say, 46 and 47 for the first flow. 



It is noticeable that the wells of lowest temperature on 

 the west side of the valley are near the courses of the larger 

 streams and that the higher temperatures are found in the 

 interstream areas. The waters of these streams, derived from 

 melting snow for a large part of the year, are notably cold. 



This local excessive cooling of the upper strata of the 

 earth is apparently the explanation of the high temperature 

 gradient of 1 for 28^ feet as compared with 1 for 50 

 or CO feet, the average increase as found in deep dry wells, 

 shafts and mines. 



The wells with higher temperatures about Swede Cor- 

 ners and along the lower course of the Conejos, with ad- 

 jacent areas of lava, in all probability derive their excess 

 of heat from subterranean bodies of uncooled igneous rocks. 

 Uses of the Water. 



The principal use of the artesian water is for household 

 purposes, and most of the houses, even on many of the re- 

 mote ranches, have running water piped into the kitchen 

 and bathroom. Some wells, particularly in Monte Vista, 

 which have not sufficient head to force water into the houses, 

 yet flow freely at the ground level, are used to operate 

 hydraulic rams, which throw a smaller stream to the desired 

 height. 



The artesian water is also especially desirable for stock 

 purposes because of its moderate and constant temperature, 

 which is high enough so that the wells remain open in 

 winter; because of its continuity of supply without pumping 

 or other care ; and because of its freedom from contamina- 

 tion. Wells are bored here and there over the stock ranges 

 in the valley by private persons or by neighborhood asso- 

 ciations. 



The waste flow from the household wells is either run 

 into irrigating ditches or is used for the irrigation of gar- 

 dens and truck patches. In the town lawns, gardens and 

 shade trees are irrigated from the overflow of the wells. 

 The surplus not so used runs into the gutters and is ordi- 

 narily collected into a ditch outside the town and used for 

 field irrigation. 



In certain sections of the valley the artesion water is 

 an essential factor in irrigation. These regions are largely 

 confined to the west side of the valley, where the west 

 side of any tract is the higher. Areas where many wells have 

 been sunk for this purpose are (1) the region between Henry 

 station and Bowen schoolhouse; (2) along Rock creek; (3) 

 in the neighborhood of Veteran schoolhouse; and (4) in the 

 Warner neighborhood. In the first of these localities the 

 wells were sunk for the purpose of irrigating grain, but 

 in the last three chiefly for the purpose of irrigating native 

 hay. Native meadows, since they are not cultivated from year 

 to year, have many little irregularities and hummocks which 

 can not be irrigated from ditches. It is customary to irri- 

 gate such places, if of sufficient area, by a well sunk on 

 the highest point. 



In the Veteran and Warner neighborhoods the wells are 

 used to irrigate both grain and hay, and their development 

 Vas largely the result of the failure of ditch water. For 

 the same reason many wells have been sunk toward the 

 center of the valley in the Hooper and Mosca districts, 

 where the supply of ditch water has been very inadequate in 

 recent years. A recent development of the use of wells for 

 irrigation is the constructon of about fifty 6-inch wells in 

 the vicinity of Henry station and westward as far as the 

 Fountain neighborhood. These in general have been very 

 successful. 



The average well, if allowed to flow continuously, undis- 

 turbed, will wet an area of not more than one-half acre 

 around the mouth of the well. The greater number of wells 

 are used simply to supplement the flow in the ditches. The 

 supply of ditch water early in the season is always sufficient 

 to raise the "sub." Then, later in the season, when the ditch 

 water fails, the ground being already wet, the steady flow of 

 artesian wells is of great value. Where wells are not to be 

 used in connection with the ditch water a reservoir is a neces- 

 sity, unless they are very large. In many parts of the valley, 

 owing to the loose texture of the soil, reservoirs will absorb 

 the entire flow of a well for a year before holding water. It 

 is suggested that it wouid be a good plan to construct reser- 



