Water levels in the karstic San Andres limestone aquifer of the Roswell Artesian Basin, New Mexico, display significant variations on a variety of time scales. Large seasonal fluctuations in hydraulic head are directly related to the irrigation cycle in the Artesian Basin, lower in summer months and higher in winter when less irrigation occurs. Longer-term variations are the result of both human and climatic factors. Since the inception of irrigated farming more than a century ago, over appropriation of water resources has caused water levels in the artesian aquifer to fall by as much as 230 ft (70 m). The general decline in hydraulic head began to reverse in the mid-1980s due to a variety of conservation measures, combined with a period of elevated rainfall toward the end of the twentieth century.