GEF

Unit 5  |  Toward Sustainable Water Systems 128 WATER CONCEPTS: THE OGALLALA AQUIFER The current water struggles of farmers are not limited to those in developing countries. In the U.S., the Ogallala aquifer in the states of Texas, Oklahoma, Kansas, and Nebraska supplies 27 percent of the nation’s irrigated farmland. Much of the water in the aquifer is fossil groundwater that has been there for 10,000 years or more. Surface water recharges the Ogallala extremely slowly, trickling down at a rate of about half an inch per year. Following World War II, farmers began pumping this fossil groundwater with inexpensive diesel and electric pumps in order to supply vastly expanded irrigated agriculture. By the late 1970s, land watered by the Ogallala accounted for about one fifth of the irrigated farmland in the U.S., providing a significant portion of global wheat harvest. Ogallala aquifer water is being drawn down at a rate ten times faster than it is recharged. In addition to threatening the future availability of irrigation water, unsustainable groundwater pumping causes an increase in soil salinity. It also causes land subsidence, or sinking, as the supportive pressure of underground water is removed. As in important agricultural areas around the world, farmers around the Ogallala aquifer are beginning to recognize the importance of reducing water demand and looking beyond unsustainable use of groundwater.