Technical Abstract: The performance of large-scale irrigation projects worldwide has been disappointing to the international community. Continued poor performance could limit our ability to provide food and fibre for a growing, more affluent world population. Improvement in the productivity of large irrigation systems is a key component to assuring future adequate food and fibre supplies. This paper discusses the reasons for poor performance of these schemes and proposes a method to improve their performance. A main problem is that operation of these irrigation systems is not tied to productivity. As a result, the dispersive nature of these large open canal distribution systems causes extreme variability in water delivery service to users. The remedy is to break the system down at key intermediate locations within the network and to improve physical and administrative control at those locations