Amongst individuals the water-right is generally defined by a measurement of time, a certain number of days or hours—during which the owner controls the entire flow of the spring or stream. It is only when the water is more abundant that we find another method of fixing the right of water, defining it by bulk. The water is then said to be demarcada, as the unit is customarily the marco, or the volume which passes through an opening about twenty-one centimetres in width and eight in height. The marco has infinite divisions, and each subdivision has its own name—the naranja, the bombilla, the paja, and so on.
As all the water is utilized, and the rights of all are equally entitled to respect, the division of the water into marcos (demarcacion) is in practice merely a proportional distribution of it amongst those who have rights to it. If the sum total of rights expressed in marcos represents something like the total flow of a stream during an average season, in the time of low water it is disproportionate, and the water no longer flows to the tops of the marcos. In other words, the quantity of water granted to each rises or falls with the rise or fall of the stream itself.
Theoretically, when the water-right is defined in marcos it is permanent. Often, however, it is impossible to grant each proprietor a permanent title to the water. Even in oases where the water is "demarked," the turno—that is to say, the turn of the proprietors to have water—which is the absolute rule in the poorest oases, reappears during the months of scarcity, in winter, when there is no rain, and at the beginning of summer. It reappears also when the right of ownership has been broken up into fractions that are too small, and it is better to grant a larger volume of water for several hours instead of a constant stream of water which would be too scanty for profitable use. At Andalgala the "turn" is sometimes obligatory, and regulated by custom, in channels where the irrigating proprietors are too numerous; at other times optional, and settled by convention amongst the owners themselves, when water is scanty. At Valle Viejo (Catamarca), when the water runs low, they set up the mita; that is to say, the sluices remain closed in each channel during four days out of eight, each proprietor in turn giving up his right to a permanent supply in order to have a double allowance when his turn comes. The turno is, therefore, a general practice. Everywhere we can see the farmers on the watch along the acequias, waiting for the moment to close their neighbour's trench with a pellet of clay and to let the stream into their own trenches with a blow of the spade.
The most minute precautions are taken in order that no one shall suffer injury. As the irrigation is always slower and less thorough during the night, they take it in turns to have the day and the night alternately. When the community receives the water from another community higher up the stream, the succession of "turns" amongst its members differs every time. The water comes down charged with sediment, pushing in front of it a mass of liquid mud, as the flush of a torrent does. It takes some time for the stream to become regular and clear. The first irrigator therefore exercises his right under unfavourable conditions. In the local phraseology the volcada de agua is not as good as the corte de agua, which means the irrigation that begins when the acequia is full.
Irrigation entails the services of quite a staff of arbitrators and administrators. The head men, who have jurisdiction of a higher order and secure the accurate distribution of the water amongst a number of channels or communities, are now, as a rule, officials of the administration, appointed by the provincial authorities (juez de Irrigacion at Catamarca, juez de rio at Rosario de Lerma). But the juez de agua of each community or each channel is a syndic elected by the interested parties. At Santa Maria the juez de agua is elected by the owners and confirmed by the Government. He controls irrigation throughout the department, settling all differences, submitting plans of work to a meeting of the owners, and assigning their respective charges in labour and contributions according to their rights.
This land of customs and traditions is also a land of lively movement. The briskness of the traffic is primarily due to continuous exchange between the various zones of the mountainous district. This large trade, so scattered that the railways could not dream of satisfying its needs, is carried, in the old fashion, on the backs of mules. The lively aspect of the roads between the tableland and the lower valleys of the region, the brisk interchange of goods between zones with different climates, is one of the common features of life on the Andes.
But the classic spectacle presents a different aspect in different latitudes. In Peru, and in southern Bolivia, the higher valleys—Jauja, Cuzco, the Pampas of Cochabamba and Sucre—have centres of dense population and agricultural wealth at a height of between 9,000 and 11,000 feet. They raise cereals, and receive from the tropical districts (montañas and yungas) sugar, cane-brandy, cocoa, and coca-leaf. The valleys of the Argentine Andes are usually at a less elevation than the yungas and montañas of Bolivia and Peru. But they are not hot districts, and have not tropical vegetation. Frost prevents the harvesting of sugar-cane at Salta, at a height of 4,000 feet. As to the coca-leaf, which is not as much used here as in the north, the Argentine valles do not send it to the tableland, but receive it indirectly from there, through the southern yungas. In default of tropical crops, the Argentine valles sow wheat and maize, which they sell to the Indians of the cold districts of the Puna for wool and salt.
These commercial currents are of very ancient, probably pre-Columbian origin. Boman has discovered ears of maize in the prehistoric tombs of the Puna de Atacama.[18] The Puna, at a height of 11,000 to 12,000 feet, is permanently inhabited, unlike the high valleys of the Cordillera de San Juan, which are occupied only during the summer season by Chilean shepherds. It is primarily a pastoral and mining region, but it has some tilled land, at more than 6,700 feet above the level of the valleys. The higher limit of annual cultivation in the cold districts, which is fixed by the summer temperature, does not fall in the same way as that of arboriculture in warm districts, because trees suffer from the winter frosts. The Indians of Cochinoca and Susques sow lucerne and barley for fodder, and the quinoa and potato for food. Transport between the Puna and the valles is carried on by the inhabitants of the Puna, and is not shared by the vallistas. They are especially active in the north, in the province of Jujuy. Belmar shows how important the sales of the Puna woollen goods were by the middle of the nineteenth century.[19] These fabrics were used by the mill-owners of the Rio Grande de Jujuy to pay for the work of the Indians of the Chaco, whom they employed in the sugar-cane harvest. The competition of the manufactured products of Europe now menaces the domestic weaving of the Puna, just as the competition of the flour of the Pampa menaces the cultivation of cereals in the valles.
Besides this traffic of local interest the valles serve for a traffic of a higher, almost a continental character. It seems certain that during the pre-Spanish period the road from the Peruvian tablelands to Chile avoided the inhospitable desert of the Puna de Atacama, entered the region of the valles to the east, and crossed the Cordillera in the latitude of Tinogasta, or even a little further south. That was the route of the armies of the Incas, which in the fourteenth century came as far as Maule. The pre-Columbian roads, of which Boman has found traces between the Valle de Lerma and the Valle Calchaqui, seem to correspond with this direction of traffic. By this route the long quechua passed amongst the Diaguites populations. The conquerors followed the Indian guides. Almagro, in going from Peru to Chile, passed through the valles at the eastern edge of the Andes.