Agriculture in the prehistoric Southwest
After the Hohokam disappeared, Spanish explorers of the 16th century noted the use of canal irrigation in only two areas of the Southwest: eastern Sonora, primarily practiced by the Opata and Lower Pima, and among the Pueblos of northern New Mexico. Irrigation by the Opata and Pueblos had different objectives. In Sonora, with a long growing season, two crops of maize a year were grown in river valleys. The spring crop during the dry season was dependent upon irrigation; the summer and fall crop during the rainy season utilized irrigation to supplement rainfall. The necessity of irrigation probably required a high level of social organization. In New Mexico, with only one crop of maize per year possible, irrigation was supplemental and the lesser dependence on irrigation implies less social organization than in Sonora.
Urban water management in Monterrey, Mexico
The irrigation districts within the watersheds serving the MMA are the Bajo Río San Juan (BRSJ) irrigation district #26 (ID026) and the Bajo Río Bravo (BRB) irrigation district #25 (ID025). The farmers in these two irrigation districts receive water through a unique compensation arrangement that includes crop loss payments on the order of US$100 per hectare un-irrigable land due to the diversion of water to Monterrey plus an additional 60% of the diverted water to be returned to farmers as treated effluent via the Ayancual Creek, Pesquería River. While this has been a success, the Mexican irrigation sector will continue to face intense competition for water given: (a) low water productivity in agriculture leading decision-makers to allocate water to higher productivity uses particularly in cities; (b) priority accorded to the domestic use component of municipal water supply; (c) and Mexico's national interests in meeting its water sharing obligations with the United States.