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Extensive ground-water pumpage for agriculture from 1952 to 1968 played a significant role in the development of more than 6 ft of land subsidence measured between 1926 and 1992 in Antelope Valley. Since the 1970s, the reduction of irrigated agriculture in this arid, high-desert valley has paralleled dramatic increases in population and urban land use. Concurrently, ground-water pumpage has declined sharply, to the lowest levels in decades. Although currently less than at any time since the 1940s, annual ground-water extraction still exceeds the estimated mean natural recharge to the valley by nearly two-fold. As a result, groundwater levels, historically lowered throughout the central part of the valley, continue to decline in urban and isolated agricultural areas where ground-water use is high. The population of Antelope Valley is projected to grow from 260,400 in 1990 to 690,000 by 2010, and water demand is expected to exceed projected supplies by the year 2004. Ground-water supplies have satisfied 50-90 percent of the annual water demand in Antelope Valley during the period of development, and will constitute a substantial component of the future water supply. If ground-water levels are maintained at approximately their historic low levels, the subsidence presently observed may be only a modest fraction (perhaps 35-65 percent) of that which will ultimately occur. Past agricultural and current municipal-industrial demand for ground water creates a legacy of ongoing aquifer-system compaction, land subsidence and related problems, and the challenge to manage the resource within beneficial limits.