The first Euro peans who entered the upper Rio Grande of northern New Spain in the sixteenth century encountered Pueblo Indians whose Anasazi an cestors were the first horticulturalists of the region to de velop stable food production by the use of rain harvesting and intricate sys tems of water control. Due to Spanish col on iza tion goals, new and more expansive settlements were to be located throughout the Camino Real de Tierra Adentro fol low ing the Rio Grande and its tributaries into the high sierras of northern New Mexico. Water from snowmelt was essential to the estab lishment of agricultural com munit ies in valley floors where isolated pockets of arable land were located in proximity to streams, creeks, and arroyos. The His panic settlers from central Mexico and their Indian allies who crossed through the deserts of Nueva Vizcaya, now Durango and Chihuahua, into the Jornada del Muerto eventually reached the alpine watersheds to the north. Here, they con structed gravity flow irrigation ditches transforming the semi arid landscape into agrosys tems that have survived into modern times as examples of the millennial culture of water of Arab, Iranian and Saharan origin that reached the New World. At present, these com mun ity sys tems of irrigation, acequias, operate as local water management institutions under a commission form of self government and are authorized in New Mexico Statutes as bodies corporate (N. M. Stat. Ann. § 73-211). A board of three elected commissioners admin is ters the rules and regulations for each ditch, and a mayordomo (ditch superintendent) distributes the water in the acequia madre (main canal) to the parciantes or acequia members who cooperate in the labor and maintenance of the sys tem. Under modern water laws, the rights to use water are owned by the indi vidual farmers, but the phys ical infrastructure to divert and convey the water to the fields is held as common prop erty by the com mun ity of irrigators. As water management institutions, the ditches perform many agro ecological ser vices for human sustenance, but they also recharge the aquifer and extend riparian cor ridors that provide habitats for plant biodiversity and wildlife refuges.