ABSTRACT
The development of irrigation in Mendoza forms the earliest modern example in the region, of the deliberate use of the water resource to achieve general economic and social development. The original provincial legislation governing irrigation, and water use in general, was a model in its time and established a very particular and successful mix between public and private responsibility for water management. The result was the creation of an irrigation based society in Mendoza with a very profitable agriculture centred on the production of wine.
The Nature of Irrigation in Mendoza. The irrigated areas of Mendoza are oases in an arid region. The annual rainfall is nowhere in the province greater than 200 mm. and in most areas less. The major irrigated districts are located on the River Mendoza and the River Tunuyan in the north of the province and on the River Diamante and River Atuel further south. All four rivers are tributaries of the River Desaguadero, which does not reach the sea.
The irrigation systems in the north and centre are without regulatory structures. In the south there is an elaborate system of regulation with a series of hydroelectric dams and compensatory structures to ensure the water supply. It is estimated that there are some 3,000 kilometres of canals serving more than 500,000 hectares, not all of which is under cultivation at present. In recent years, particularly around the city of Mendoza, a considerable number of canals have become incorporated within the urban area.
34In the last twenty years the supply of water from surface sources has been augmented through the extensive use of groundwater. The expansion in the number of wells reached a peak around 1970 and occurred with very little public control, although with considerable public support. More recently, with higher river flows than the long term average and with a significant decrease in the area under irrigation, the use of groundwater has declined and a large number of wells are out of use.
The Development of Irrigation. Agriculture in Mendoza is based on the production of grapes for wine. At the present time this accounts for around 75% of the total value of agricultural production in the area. This dominance of grapes for wine is, however, a phenomenon of this century. The original development of the region was based on the production of forage and grain crops for the feeding of livestock and for export to Chile. This changed at the end of the nineteenth century with the construction of the railway linking Mendoza to Buenos Aires.
The railway brought not only new markets but also mass immigration. The expansion of irrigation was coupled with change in the structure of agriculture which led to increasing domination by the production of wine for the growing domestic market. By 1930, the present agricultural structure had been established and the availability of water for irrigation began to be the most important restriction on further growth.
In the third period, from 1930 through to the early 1970s, the pressure on water resources was alleviated by the increasing use of groundwater. In the northern most irrigated zone, around the city of Mendoza, there was increasing competition from other water uses. In this period, in the southern zone, the supply was augmented by the building of regulatory structures by the federal government with the construction of hydroelectric generating plants.
From the coming of the railway to the early 1970s the development model upon which the water using system was built led to sustained economic growth and the generation of high regional incomes. Naturally, there were periods of recession, but growth was always resumed. In the last 15 years, however, the model has failed as its base. The domestic demand for wine has declined due both to the continuing crisis in the Argentinean economy, which has led to lower incomes, and to a change in consumer habits involving the substitution of wine with beer and soft drinks. The importance of agriculture in the regional economy has suffered, therefore, a long-term secular decline.
The Administration of Water. Constitutionally, the administration of water resources in Argentina lies under the responsibility of the provincial governments. In the case of the Province of Mendoza, the 35provincial government using this constitutional facility has dominated the management of water in the province despite a national tendency to centralization for most of the last half century. It has done so through a very particular system for the administration of the resource.
The water management system in Mendoza consists of a diffuse set of bureaucratic institutions with partial and overlapping responsibilities. The activities of this complex of agencies are very limited and the real authority for water management lies in the hands of two complementary institutions, the Departamento General de Irrigacion (DGI) and the Inspecciones de Cauce. These two institutions dominate the management of water in the province despite the limitation of their formal roles to the supply of water for irrigation.
These two institutions are interrelated, but independent, and occupy a very special constitutional position within the province. The DGI is responsible for the complex of works which include the river, the diversion structures and the main canals and, more recently, groundwater basins, while the Inspecciones de Cauce are responsible for the secondary irrigation network. They are both autonomous public institutions and raise their own revenues.
The Effectiveness of Management Within the DGI. The DGI is one of the oldest water management institutions in Latin America and the Caribbean. In general terms, the DGI has been and remains a successful institution but it shows signs of its age and of problems of adjustment to changing circumstances. The success of the DGI has undeniably been linked very closely to the success of the economic model applied in the province. This has allowed the DGI to develop a strong base, an institutional position and role that permits it to meet crises, such as the present challenge to the basis of Mendoza's irrigation society.
The DGI is only responsible for the supply of water. It has no competence over the use of water within the farm. It suffers, through the reduction of its income, when farm production is depressed. Financially, it is an agent of the water users, although for major works income is provided from general government revenues. The current depression in the wine industry, coupled with changes in the industry's structure, has resulted in a considerable transfer of income from producers to distributors and has considerably reduced the income of the DGI. This in turn has affected its capacity to improve the efficiency of the tapping and distribution of irrigation water.
