Determining the optimal size of water users' associations

In 1985 the General Irrigation Department (DGI) of the Province of Mendoza, Argentina, launched a water users' associations reorganization program to attain administratively more effective associations. At that time there were 760 water users' associations (WUAs) managing a total irrigated area of 360,000 ha. Under the reorganization program all water users' associations of less than 1000 ha were merged into larger organizations. The main obstacle to the viability of small WUAs was the lack of adequate funding to perform their irrigation water management responsibilities. At that time it was thought that the ideal administrative area should range from 10,000 to 15,000 ha. Eight years after the reorganization, the total number of WUAs was reduced to 360. This paper reviews the experience with the reorganization program. It concludes that the optimal size should be between 3000 and 10,000 ha to minimize management costs. This conclusion is based on the detailed budgets of nine new WUAs administering from 500 to 14,000 ha.