ARTESIAN WELLS. 425 



THE RELATIVE PRODUCTIVE TOWER OF THE SEVERAL WATER-BEARING ZONES. 



The number of wells taking water from the Laramie and Denver 

 formations is too small to afford material for reliable estimates of the 

 productive power of these horizons. For the three zones of the Arapahoe, 

 however, the number is larger, and approximate estimates may be inferred 

 from the original yield of the wells, notwithstanding the fact that the 

 actual number of wells drawing their supply from the several zones varies 

 very considerably. 



The average daily yield of .the Arapahoe wells, supposing them all to 

 have flowed at the rate originally recorded, would have been — 



Gallons. 



For the upper zone 64, 075 



For the intermediate zone 45, 540 



For the lower zone 93, 673 



These figures are based upon reported actual flows, and for the upper 

 zone are the average of -22 wells, for the middle zone of 8 wells, and for 

 the lower zone of 27 wells, the distribution of the wells including the 

 entire center of the Denver Basin. It thus appears that the rate of yield 

 of the several zones is in general accord with their observed texture and 

 composition. 



THE YIELD OF THE WELLS. 



Daily yield. — In a preceding section the yield of the artesian wells of the 

 Denver Basin was considered with reference to the adequacy of the rainfall, 

 and for the purpose of bringing the results within any possible error of 

 an overestimate the original rate of yield was regarded as an actual daily 

 yield, and all the wells as flowing at the same instant. The figures repre- 

 senting the total amount of water were thus far in excess of those which 

 would represent the actual discharge by flow and by pump, but clearly 

 established the adequacy of the rainfall to the power of transmission of 

 the strata. 



Of the actual quantity of water supplied by the artesian wells of 

 Denver and its suburbs at a stated time, it is difficult in the absence of 

 the requisite data to form an estimate; and such data, satisfactory and 

 sufficiently complete, it has been impossible to obtain. Only a minority 

 of the wells have ever made a continuous draft upon their supply, the 



