BETTER GROUND-WATER MANAGEMENT 285 



50 million gallons a day in 1930 to about 150 million gallons 

 a day at the present time. Water levels simultaneously de- 

 clined throughout the areas in some instances to more than 

 100 feet. The amount removed from storage, however, is small 

 in comparison with the vast quantity pumped in the past 20 

 years. The artesian pressure has declined and a greater inflow 

 into the Houston area has resulted. The encroachment of 

 salt water is improbable at least for many years. The most 

 serious aspect of the lower pressure, therefore, is the increas- 

 ing cost of pumping water. It is this cost and the realization 

 that the ground-water reservoir is being drawn upon heavily 

 which have led to increasing emphasis on bringing in supple- 

 mentary water from surface sources. 



About 25 miles west of Houston and close to the recharge 

 area, rice growing has developed, with a fivefold increase in 

 pumpage in a period of two decades. In spite of this, in the re- 

 charge area the water table has shown no material decline 

 during the last decade. The declines in artesian pressure in 

 this general area, as at Houston, are not due to consistent de- 

 ficiency in replenishment but to the slow passage of water 

 from the recharge area to the wells. 



In the Houston area, therefore, heroic measures appear to 

 be unnecessary, other than a watchful eye over the rate of 

 pumping in future years and the parallel supplementation 

 from surface sources. If the two were simultaneously managed 

 by one agency, the area should not be confronted with signifi- 

 cant water problems for some years to come. 



Florida, Southeast Coast. The metropolitan Miami area 

 currently uses about 80 million gallons a day, of which 50 mil- 

 lion are for municipal use, with the remainder for irrigation 

 and industrial use. Water levels have been lowest principally 

 between the Miami Canal and other uncontrolled tidal canals. 

 Salt water has moved from Biscayne Bay into the principal 

 aquifer. Saline waters entered, for example, Miami's Hialeah 

 well field in 1939. Locks and other control structures are 

 planned on the major canals discharging into Biscayne Bay 

 in order to hold the water on the upstream side during dry 



