Long-Term Irrigation Trends – Texas High Plains

Abstract

The Texas High Plains is the most critical groundwater depletion area of the High Plains (Ogallala) Aquifer. The aquifer underlies parts of eight states in the Western Great Plains. Irrigation initially expanded in the central counties of the Texas High Plains during the major drought of the 1930s and peaked during the mid-1970s. Thereafter, continuing groundwater depletion of the Ogallala Aquifer, escalating pumping energy costs, low farm profits, and government set-aside programs stimulated a decline in irrigated area. The irrigated area in the Texas High Plains declined from a peak of 2.25 million ha (6.0 million acres) in 1974 to 1.62 million ha (4.0 million acres) in 1989. Estimated annual groundwater use declined from 10.0 km3 (8.1 million ac-ft) in 1974 to 5.6 km3 (4.5 million ac-ft) in 1989. Although reduction in irrigated area was the major cause of the reduction in groundwater use, improved irrigation systems and water management practices have contributed to reduced water application. Groundwater depletion, which averages about 30% of predevelopment storage, will continue to limit long-term irrigated agriculture. However, continued reduction in irrigated area and adoption of water conservation technology are moderating the rate of groundwater use and water-table decline.