Irrigation developed on the Texas High Plains using water from an exhaustible ground water resource (the Ogallala aquifer). Pumping from the Ogallala in this region has diminished the resource to the point that some areas have already made a transition back to rain-fed or dryland agricultural production. This transition from an intensive agriculture to an extensive one (irrigated to dryland) offers a unique opportunity for study in the United States, one that can provide lessons for other regions that eventually will face such a transition.

The focus of this case study is the implications of aquifer mining. They include impacts on agriculture, soil erosion, and present policy options most likely to effect a smooth transition to dryland farming considering minimizing long-term environmental degradation as well as political and economic feasibility.

Description of the region

The Texas High Plains is a nearly level to undulating semiarid region that includes approximately 35,000 square miles in 42 counties. Average annual rainfall ranges from 14 to 21 inches, and the growing season varies from 180 to 220 days. Elevation ranges from 3,000 to 4,000 feet above sea level.

The major soil resource areas include the hardlands (54 percent of the total), composed of fine-textured clays and clay loams, such as the Pullman and Mansker series; the mixedlands (23 percent of the total), composed of the medium-textured loams and loamy sands, such as the Portales, Olton, and Amarillo series; and the sandylands (23 percent), composed of the coarse-textured sands, such as the Brownfield and Tivoli series (Godfrey, Carter, and McKee, 1967).