426 GEOLOGY OF THE DENVER BASIN. 



majority drawing upon it for but a few hours of the day or as domestic 

 purposes demanded. It is probable, indeed, that all in use at the time of 

 the investigation, December, 1890, could have been pumped unremittingly 

 for a considerable length of time, but it would have resulted in a lowering 

 of the water-level and its passage beyond the reach of many of the 

 pumping plants. The best approximate estimate of the daily yield of the 

 Denver and suburban wells at the close of 1890 is, perhaps, 1,500,000 

 gallons. This is a little more than one-seventh of the original rate of 

 discharge, that for 1886 having been closely determined at about one- 

 fourth the original. Since 1890 there has been a still further decrease, 

 and the city is now almost wholly supplied with water brought from a 

 distance. 



In the months of May and June, 1884, there was a marked increase in 

 pressure and flow in several wells, all of which were in the 375-foot scam. 

 Among these wells were the Opera House (pressure doubled), the Eckhart, 

 Electric Light, and Steam Heating Wells. Various explanations of this 

 phenomenon have been advanced, none of which is wholly acceptable. 



Van Diesfs estimate of total yield to date. In Collecting aild tabulating tllC Statistics 



in 1890, Prof. P. H. Van Diest, of Denver, estimated approximately the yield 

 of the Denver Basin from the inception of artesian-well boring to the close 

 of that year. His discussion is as follows: 



The average thickness of the water-bearing strata of the wells in and around 

 Denver is 135 feet (based on a statement for North Denver by an experienced well 

 contractor). Forty miles, or 211,200 feet, of lineal outcrop by a width of 135 feet gives 

 28,512,000 square feet of water collecting or rather water-retaining area. 



The data of the original height of flow above and of the present level of ttite 

 water-table in wells below the surface give an average difference in height of 70 

 feet. A mass of sandstone 40 miles long, 135 feet wide, and 70 feet high contains 

 1,995,840,000 cubic feet. 



The absorption to saturation of this sandstone can be placed at 7 per cent of 

 its weight, according to tests of similar sandstones made by the committee reporting 

 on building stones for the Colorado capitol. Seven per cent is the equivalent of 

 349,272,000 [299,535,067 : author 1 ] cubic feet of water, or 2,019,540,000 [2,240,682,548: 



1 The author took the weight of stone at 134 pounds per cubic foot, an average of several 

 specimens, and a cubic foot of water at 62.J pounds, or 7.48052 gallons. Mr. Van Diest evidently 

 assumed somewhat different dala. 



