The Ogallala Aquifer is one of the largest aquifer systems in the world in terms of area covered (174,000 square miles), underlying parts of eight states of the Great Plains: Texas, New Mexico, Colorado, Oklahoma, Kansas, Nebraska, Wyoming, and South Dakota (Nativ, 1). Recharge into the Ogallala Aquifer can take place through diffuse infiltration directly into Ogallala outcroppings on the western and northern boundaries. Another source of recharge is through the playa lakes and riverbeds.
Nativ (1988) reported that studies have shown that infiltration through riverbeds is insignificant because of the poorly developed drainage system in the Southern High Plains (Nativ, 6). She also reported that infiltration studies have shown that recharge through playa lakes is the more likely method of recharge rather than the diffuse method. She reported recharge rates of 0. 11 to 1. 6 inches per year (Nativ, 6). The Ogallala Aquifer will likely experience the decline in its water level in the future.
From the practical perspective, in some regions the Ogallala Aquifer is considered already as an exhaustible aquifer due to decreasing water recharging rates. The general consensus among experts is that as the amount of water in the Ogallala Aquifer decreases, the crop production in its area will decrease. Water use of the Ogallala Aquifer varies across the region due to water availability, measured by saturated thickness, and by cost of pumping, measured by depth to water or pumping lift (Johnson et al, 2004).
Depth to water is smallest in the central regions with depths less than 50 feet and greatest in the northern and southern regions with depths over 300 feet (Nativ, 2). Hardin and Lacewell (1980), in a study of irrigation pumping from the Ogallala Aquifer, found that both producers and society benefit from limiting annual withdrawal of groundwater from an exhaustible aquifer. The objectives of the study were to examine the effects of the economic life of the water supply of the Ogallala Aquifer and compute breakeven discount rates for unlimited water use and for various levels of limited annual rates of water withdrawal for the aquifer.
The results showed that, with sprinkler irrigation, the number of years that the initial number of acres can continue to be irrigated is 38 years for unlimited water use, 44 years for the limitation of a 4-foot decline, 38 years for the limitation of a 3-foot decline, and 86 years for the limitation of a 2-foot decline (Hardin and Lacewell, 40). The authors cited other issues that must be addressed such as developing the institutions, both regulatory and economic, to provide incentives for individual irrigators to modify annual withdrawal rates with the objective of maximizing the value of the resource (Hardin and Lacewell, 43).
Renshaw (1963) evaluated the question of managed groundwater reserves in the Southern High Plains. The study considered two cases with different results. The first case of optimal mining where aquifer recharge is negligible relative to withdrawals used data from the High Plains Underground Water Conservation District for the case study. Renshaw recommended that nonprice rationing be used which can include agreements among irrigators to limit withdrawal. Renshaw found that with 1960s technology and current withdrawal rates, the economic life of the aquifer was 30 years (Renshaw, 289).
By reducing withdrawal by 15%, irrigators would realize a return on foregone income of 7. 5% and by reducing withdrawals by 50%, the return would be 4% (Renshaw, 289). Lansford et al. (1983) evaluated the on-farm economic impacts of the declining Ogallala Aquifer in New Mexico. The findings indicated that the Southern High Plains of New Mexico, bounded in the north by the Canadian River, will transition from irrigated to dryland cropping patterns between the years 2000 and 2020 for a majority of the cropland acres (Lansford et al, 33).
They found no significant difference in water use between voluntary and mandatory irrigation water conservation measures. Warren et al. (1982) studied the economic impacts of the declining Ogallala Aquifer in western Oklahoma. The study area was in the Central Formation of the Ogallala Aquifer similar to the Texas Northern High Plains. The study found that irrigation acreage would increase in the near- and mid-term and that the future of irrigated agriculture in the study region was positive (Warren et al, 75). This reinforces the findings of the Lansford et al.
(1983) study in New Mexico that distinguished the potential for future irrigation between the areas north and south to the Canadian River. WORKS CITED Hardin D. C. and Lacewell R. D. “Temporal Implications of Limitations on Annual Irrigation Water Pumped from an Exhaustible Aquifer. ” Western Journal of Agricultural Economics, July, 37-44, 1980 Johnson J. W. et al. Evaluation of Water Conservation Policy Alternatives for the Southern High Plains of Texas, Department of Agricultural and Applied Economics, Texas Tech University, 2004 Retrieved from <http://ageconsearch. umn. edu/bitstream/34788/1/sp04jo02. pdf>, June 15, 2009
Renshaw E. F. “The Management of Ground Water Resources,” Journal of Farm Economics, 45:285-296, 1963 Nativ R. Hydrogeology and Hydrochemistry of the Ogallala Aquifer, Southern High Plains, Texas Panhandle and Eastern New Mexico. Report of Investigations No. 177. Bureau of Economic Geology, Austin TX, 1988 Lansford R. R. et al. “The On-Farm Economic Impacts of the Declining Ogallala Aquifer for the New Mexico High Plains,” The Journal of American Society of Farm Managers and Rural Appraisals, 47:31-36, 1983 Warren J. et al. “Economics of Declining Water Supplies in the Ogallala Aquifer. ” Groundwater, 20:73-79, 1982