66 CONSERVATION OF GROUND WATER 



conservation measures resulting from an educational pro- 

 gram started by the Nevada state engineer in 1945. In 1947, 

 it was estimated that wastage had been reduced to less than 

 15 per cent of the discharge from wells and springs, mostly 

 through voluntary cooperation of the well owners, although 

 the state on two occasions sealed "wild" wells and charged 

 the cost to the well owner. Even so, by 1948 the total 

 ground-water draft had risen to 34,700 acre-feet, and in the 

 following summer the city of Las Vegas placed restrictions 

 on lawn sprinkling. Also in 1949, the state engineer pro- 

 hibited the drilling of any new irrigation wells in a 42- 

 square-mile area including Las Vegas and about 90 per cent 

 of the area of ground-water development. Municipal and 

 domestic wells may still be drilled within this area, however. 

 This regulation is designed to prevent any major increase 

 in draft within the area of concentrated development. The 

 development of the entire artesian basin is considered to be 

 approaching the limit set by natural replenishment, and 

 drilling of additional irrigation wells is discouraged 

 throughout the valley but not yet strictly prohibited. 



In Las Vegas Valley there is a shallow ground-water res- 

 ervoir, as in the Roswell Basin, which receives water by 

 upward leakage from the artesian reservoir and, in the 

 vicinity of Las Vegas, waste water from irrigation, cooling, 

 and sewerage. About 8,000 acre-feet of water is discharged 

 annually from the shallow reservoir by evapotranspiration 

 in an area of about 5,000 acres where the water is within 10 

 feet of the surface. This shallow water thus constitutes a 

 potential source of additional water, provided that the re- 

 quirements are not large. However, for large additional 

 supplies, Las Vegas Valley looks to the Colorado River, 

 which has supplied as much as 23,000 acre-feet during war 

 years to the industrial area around the town of Henderson 

 in the southeast part of the valley but which now supplies 

 only about 5,000 acre-feet annually. The withdrawal from 

 the Colorado River by the state of Nevada is limited by 

 compact to 300,000 acre-feet a year. The state is already 



