How It Was
"Acequia" [pronounced "ah-SAY-kee-uh"] means irrigation canal and, like many Spanish words beginning with the letter A, has its origins in Arabic. The acequia madre or “mother” of the irrigation canals is deceivingly simple-looking but was a vast project with ramifications in workload and social upheaval.
The irrigation canal was a 2.5-mile-long waterway, about 3 feet wide and 4 feet deep. The canal was not lined with concrete or limestone so required constant maintenance. The canal diverted water from the river upstream, then flowed northward by gravity. Branching off from the main canal were smaller channels that irrigated the lands between the acequia and the river. After feeding the fields and orchard, the water then reentered the river downstream. Tumacácori Mission sat about center of the acequia’s sweeping arc.
Access to irrigation allowed the mission to produce enough food to also supply the presidios at Tubac and Tucson. However, the supply was not without its limits. In 1774, the mission farm was using so much water that the river further downstream was a mere trickle. Tubac’s Spanish farmers complained, and the presidio Captain, Juan Bautista de Anza, was forced to begin a rationing program. The rationing allowed a week of irrigation for the mission alternating with a week for Tubac. As late as 1777, the policy was still in place.