During extended droughts, the water captured in some West Texas reservoirs is depleted or nearly depleted. When this occurs, those dependent on surface water reservoirs for their water supply utilize ground water to make up the deficit. Replenishment of surface water reservoirs can occur quite rapidly, whereas replenishment of a ground water reservoir is generally very slow. Drought management of surface water supplies generally could be considered short term - a few years at most. Approximately 95 percent of the ground water used in the area is for irrigated agriculture.
Ground water is used to supplement precipitation.
Therefore, drought management in the southern High Plains of Texas contains two major components. The drought of 1998 emphasized how dependent we are on precipitation and of the importance of irrigation application efficiency as it relates to crop yields. Precipitation is the primary water supply source for the area served by the High Plains Underground Water Conservation District. The Water District service area covers approximately 6,869,910 acres. Average annual precipitation ranges from about 16 inches on the west side of the Water District to about 20 inches on the east side, averaging about 18 inches.