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.
Canarian Americans
Before the arrival of the Canarian settlers in 1730, the San Pedro channel was built for the exclusive use of the Canary Island colonists. It was called the "acequia madre", the "mother ditch" that crossed the city. Its waters irrigated agricultural fields around San Antonio from that time until 1906. The last channel to supply water to the citizens was dug in 1777 for the new settlers of Los Adaes, and its remains can still be seen. American historical research indicates that Canarian irrigation practices in the San Antonio colonial period can only be understood in the context of traditional irrigation practices developed over thousands of years by the settlers' ancestors in the Canary Islands.