122 CONSERVATION OF GROUND WATER 



comparison to the vast quantity pumped in the past 20 years. 

 Instead of indicating the exhaustion of the ground-water 

 reservoir, the lowering of water levels is the result of decline 

 of artesian pressure, and it is because of this decline that 

 there is now far more inflow into the heavily pumped 

 Houston area than before development began. 



Recent studies have shown that the encroachment of salt 

 or brackish water from horizons below the fresh-water bear- 

 ing sands or by invasion from the direction of the Gulf is 

 not likely to occur at least for many years. Observations 

 since 1930 have shown no significant change in mineral con- 

 tent of water pumped from representative wells; drilling 

 has shown that fresh water can be obtained from depths as 

 great as 2,500 feet in Houston. Thus the most serious aspect 

 of the lower pressure is the increasing cost of pumping the 

 water. This cost, plus the realization that the ground-water 

 reservoir is perhaps already doing more than its share in 

 meeting the rapidly expanding requirements for water, has 

 led many industries to turn to surface-water supplies. In 

 1949, the Pasadena industrial area used 30 million gallons 

 a day from the San Jacinto River, and storage reservoirs are 

 being planned for increasing the supply. 



About 25 miles west of Houston, and closer to the re- 

 charge area, is the Katy rice-growing district, where water 

 is pumped from the same ground-water reservoir that sup- 

 plies Houston. Here, too, pumpage has increased, from 

 about 18 million gallons a day in 1930 to 100 million in 

 1949, and water levels in wells have been lowered 10 to 25 

 feet in the past 20 years. The ground-water reservoir is re- 

 charged by precipitation in areas 12 miles or more north- 

 west of Katy. In the recharge area the water table has shown 

 no material decline during the last decade, indicating little 

 or no net loss in storage in the recharge area. The declines 

 in artesian pressure at Katy, as at Houston, are obviously not 

 due to deficient replenishment in the recharge area, but to 

 the slow rate at which water is transmitted from there to 

 the wells. 



