The last four decades have seen extensive development of irrigation using groundwater from the Ogallala Aquifer in the Mid-continental High Plains area (Ogallala Zone). But water withdrawn is depleting groundwater stocks causing the water table to fall. Crop production with pumped water is energy intensive and increasing energy prices weakens the competitive positions of irrigators from the aquifer relative to farmers in the rest of the nation. These issues are of concern to the entire region because local economies throughout the area are closely linked with primary agricultural production;A recursive, regional, linear programming model was constructed to evaluate effects in 1990 and 2000 of the falling water table, rising energy prices and varying export levels. The model is national in scope but simulates in detail the constraints and production possibilities in the Ogallala Zone. The model represents production alternatives with more than 2,500 rotations each with a different relationship between yields, resource use and costs. Production is constrained principally by available land subdivided according to productivity and production costs into 216 categories in the Ogallala Zone and 204 categories in the rest of the nation. The categories in the Ogallala Zone respresent eight different water situations in terms of depths to water and saturated thickness, five land management classes, and seven regional subdivisions. The model assumes competitive equilibrium; it determines prices for land, water and endogenous crops (feed grains, wheat, soybeans, cotton, hay, and silage) while other resources receive market rates of return;The area not irrigated in the Ogallala Zone because of the decline of the water table depends upon economic conditions as well as physical factors; the area depleted varies from 0.80 to 1.07 million for the period 1977-1990 and from 1.7 to 2.0 million acres for the period 1977-2000 for model solutions with varying assumptions about the level of exports and energy prices. Both increased energy prices and decreased exports reduce farm income per acre attributable to irrigation;The effect of doubling of energy prices is to increase crop prices, increase the prices of land, induce the conversion of land irrigated with groundwater to dryland, and reduce water and energy use. The most dramatic adjustments are in the Ogallala Zones where the area irrigated with groundwater declines by 48.8 and 40.9 percent for a doubling of energy prices in 1990 and 2000, respectively. The effect of decreased exports is similar except that crop and land prices fall and use of nitrogen fertilizer also declines;Much of the irrigation in the Ogallala Zone is not competitive with high energy prices likely to prevail in the future. Over the next decade high energy prices and exports may be more critical to the region then the falling water table. But the cumulative effects of the falling water table will make this an increasingly important problem in the time that follows.