February marks the 275th anniversary of the earliest known record of when the Espada Acequia (ah-SAY-key-uh) began operations in what is now San Antonio, Texas. Built to supply irrigation to the lands near Mission San Francisco de la Espada, the Espada Acequia is one of 7 gravity-flow irrigation ditches, collectively identified as the Acequias of San Antonio, which once made up an irrigation system serving 5 area missions.
In the early 1700s, Spanish missionaries in Texas were founding missions to convert the local indigenous tribes to Christianity and to protect the Spanish frontier from French incursions. As part of building permanent settlements, the founders strove to create self-sufficient communities. Much of the region in Texas occupied by the Spanish was semiarid, and irrigation was vitally necessary for the success of agriculture. Irrigation was of such importance that the Spanish colonial settlers measured cropland in “suertes,” a unit or area defined as the amount of land that could be watered in one day. The word “suerte” also means “luck.”
The early Spanish colonists brought with them the sophisticated knowledge of how to construct large-scale irrigation systems, including engineered watercourses known as acequias, an Arab technology that had been brought to Spain by the Romans and Moors. The missionaries found that the irrigation ideas widely used throughout Spain since the time of the Moorish conquest worked particularly well in the hot, dry southern Texas climate. Intermittent rainfall and the need for a reliable water source made the design and installation of an acequia system a high priority.
Thus started one of the earliest recorded engineered water projects in North America. The system consisted of the construction of 5 dams, 7 gravity-flow ditches paralleling the San Antonio River, and at least 1 aqueduct. Without the use of modern machinery, the builders constructed a 15-mile network that benefited 3,500 acres of land. The Spanish missionaries oversaw the construction, while the Native Americans provided the labor, using iron bars, wooden spades, and simple plows.
Mission San Francisco de los Tejas, founded in 1690 near Weches, Texas, was the first mission established in Texas. There are older missions currently in West Texas, but they were part of Mexico at the time they were established. In 1731, San Francisco de los Tejas transferred to its current location along the San Antonio River and was renamed San Francisco de la Espada. The irrigation system was undertaken almost immediately, as the survival of the mission depended upon water for the planting and harvesting of crops. The acequia system for Mission San Francisco de la Espada began at a dam spanning the San Antonio River. Espada Dam, the oldest dam in Texas still in use, diverted water to fields around the mission through a series of acequias. These waterways not only carried potable water and irrigation, but also powered a mill. South of the dam, it was necessary to construct an aqueduct to convey the water 15 feet above Piedras (Six-Mile) Creek. The masonry Espada Aqueduct, which brought irrigation channels across the Piedras Creek, survives as the only remaining Spanish aqueduct in the United States.
While the exact construction date of Espada Acequia is not recorded, it was in operation by February of 1740. A report by friar Benito Fernández de Santa Ana commented on the “five very abundant withdrawals from the river.” Use of the Espada Acequia was discontinued in the 1880s, but in 1895 it was cleaned, widened, and deepened. The dam was then repaired and water again supplied to surrounding farmers, a function that continues to this day. In the 1950s the Espada Dam was bypassed by a flood-control channel, but measures were taken to maintain the water level behind the dam and preserve the historic structure. Today Espada Dam is a major recreation area, part of San Antonio Missions National Historical Park.
The Acequias of San Antonio were recognized as an ASCE National Historic Civil Engineering Landmark in 1968.