In sedimentary deposits beneath arid Las Vegas Valley, ground-water levels have declined as much as 280 feet since 1912 in deeper aquifers due to pumping associated with urban development. Accompanying land subsidence has been as great as 5 feet. Predictive simulations show that by maintaining pumpage and recharge at 1980 levels and using municipal wells only during periods of peak water demand, rates of water-level decline and land subsidence will be reduced.