Problems in Applying Optimal Irrigation Plans

Planning methodology developed by the University of Idaho allows rapid determination of least-cost irrigation-system designs to assist in rehabilitation of damaged or new systems. Procedures are applied to a small 3,000 acre (1,214 ha) irrigation system damaged in the Teton Dam flood of 1977 and optimal designs to achieve specified levels of project water-use efficiency with varying costs of water and penalties or benefits for deep percolation and runoff were selected. Energy costs for each alternative were calculated. Fear of water-right loss and the paradox in western water law that encourages conservation but provides no economic incentive severely inhibit system rehabilitation. Poor understanding of groundwater-surface-water systems and the lack of recognition of possible benefits of aquifer recharge from deep percolation of irrigation water make water users reluctant to change systems.