Mission Trails Historic Sites

Tuesday, August 4, 2015


One of the most significant accomplishments of the Spanish Colonial residents of San Antonio was their construction of a complex and expansive irrigation system comprising dams, gates, and irrigation canals. Together, these systems, known as acequias, enabled the missions to thrive and determined settlement patterns. Their placement also influenced the development of other infrastructure such as historic roadways, which often followed their wandering paths, “and affected the lifestyle of the community well into the twentieth century, providing agricultural and landscape irrigation as well as drinking water” (Cox 2005).

Though the exact sequence and timing of their construction is not fully clear, construction of acequia systems began immediately after the arrival of the first settlers in the area in 1718. The term itself is derived from the Arabic word al-saqia, or ditch, illustrating the technology’s Middle Eastern origins. According to contemporary accounts, at least one acequia, the Principal or the San Pedro, was complete within two weeks of the earliest settlers’ arrival in 1718. All of the original settlers would have relied on this ditch until the final relocation of Mission San Antonio de Valero and the construction of the Valero Acequia (Cox 2005).

Acequias were constructed to serve the relocated presidio around 1720 and to serve the short-lived San Francisco Xavier de Najera (Link 2) mission. Archeological evidence indicates that the Concepción (Pajalache) acequia was also constructed during this period. It likely served the original location of the San José (Link 3) mission and was expanded upon the relocation of Mission Concepcion (Link 4) from East Texas in 1731. Acequia systems were also constructed for Missions San Juan and Espada (Link 5), to serve the final location of Mission San José, and to irrigate the farmland of the Canary Island settlers (San Pedro Acequia) (Cox 2005; Baker et al 1974).

Despite the fact that their exact method of construction remains a mystery the “essential principal of redirecting water for human use had been established at least as early as the time of legendary Roman architect and engineer Marcus Vitruvius Pollio in the first century B.C.” (Cox 2005). The Spanish had an extended history of using irrigated agriculture and would have made it a priority to have the tools and skilled labor necessary to facilitate their construction. The first part of an acequia system constructed would have been a “device to contain and direct the water into the channel, such as a diversion dam.” The main ditch, or acequia madre, would have extended from this structure (Cox 2005). This main canal was intersected by distribution canals with sluice gates at points where water was needed to irrigate specific fields (Cox 2005). Early land grants included not only property but the right to irrigate it. The standard water allowance specified in early deeds, known as a dula, was two days of water (Cox 2005). (Photo 2) Ultimately, there were over 50 miles of acequia ditches in San Antonio that served the missions, the secular settlement of Béxar, and the military presidio. A brief summary of each major system is presented below.

Concepciόn/Pajalache – This acequia is generally believed to be one of the oldest in San Antonio. It may have been constructed to serve the original location of Mission San José but was greatly expanded after the relocation of Mission Concepción to San Antonio in 1731. The acequia madre or principal ditch for this system began “on the east side of the river at a relatively large dam spanning a point just above the town’s major ford at Presa (Dam) Street.” From here, it flowed southward “along the west side of the road to the lower missions to a point 2,500 feet from the intake” where it was carried across the Acequia Valero via a canoa or hollow log. During the mid-eighteenth century, the canoa was replaced with a “substantial arched stone aqueduct” through which the acequia “flowed along the road to the mission compound, where it turned westward to return to the San Antonio River” south of its intersection with San Pedro Creek. The original acequia was approximately 3.3 miles long, but after multiple phases of additions and alterations, eventually included “more than 7.5 miles of ditches.” The Concepción/Pajalache acequia was the largest of the irrigation canals, and according to legend, was wide enough to allow small boats to row inside it. It was in continual use until 1869, when the northern portions were abandoned due to flooding concerns. Archaeological work has suggested parts of this acequia have been preserved underground near the Yturri-Edmunds complex (Link 6) as well as near the King William Historic District (Link 7).

Acequia Madre de Valero-Construction of this canal was carried out from 1724 to 1744 to supply water to the Mission San Antonio de Valero (the Alamo) (Link 8). The acequia “originated at the…ford of the Paso de Tejas” from a diversion dam in the San Antonio River. The ditch then followed a “sinuous path as it moved between the river and the low hills to the east to the south-southwest, passing through the mission grounds before returning to the San Antonio River at its largest bend.” The structure was originally three and one-half miles long; however, later additions “branching near the mission and irrigating additional farmlands to the east and south, extended its total to approximately 10 miles.” Sections of the Acequia Madre de Valero that are visible in the vicinity of the Mission Trails hike-and-bike trail can be seen within HemisFair Park (Link 9) and the elongated fish pond behind the east wall of the Alamo chapel.

San José Acequia – This acequia served the final location of Mission San José (Mission San José y San Miguel de Aguayo) and was completed around 1730. The canal began “0.8 mile south of Mission Concepción, just above a ford of the [San Antonio] river for the Mission Road crossing.” It drew its water from a diversion dam located “approximately 1,400 feet below the confluence of San Pedro Creek and the San Antonio River,” and the ditch itself followed the river’s “contours southward to pass west of the mission compound” where it “veered slightly to the east, returning to the river just to the north of Espada Dam.” The acequia was approximately three miles in length. In addition to providing irrigation for crops, it supplied water to the mission’s cattle and to a mill constructed on mission property circa 1790. Remnants of the mill were discovered by archeologists in the 1930s, and their location confirmed “the acequia’s path ran north of the mission’s north wall, then southward along the east wall” (Cox 2005). The acequia was prone to washouts at its diversion dam and was abandoned after the Civil War, though a reconstruction of the waterwheel mill is located along the north wall of the mission.

San Juan Acequia—Construction of Mission San Juan Capistrano’s acequia likely began shortly after “the mission’s first huts were constructed on May 4, 1731,” though progress was initially slow. It was finished approximately 10 years later due to delays caused by hostile native groups and an epidemic in 1739, among other factors, though it was operating in some capacity by February of 1740. The channel originated at a diversion dam located across the San Antonio River from Mission San José and traveled “southward on the east side of the river to the mission, a distance slightly exceeding 3 miles.” An eastern branch was constructed in subsequent years that “extended the acequia’s length by 2.6 miles” (Cox 2005). (Photo 2) The system, including its dam, was in regular use as late as the 1920s when it was operated by an incorporated company; however, it was abandoned in the mid-twentieth century. Archeologists excavated the San Juan dam in 1988. The structure “was constructed of large river cobbles in a mortar of lime and caliche, which formed a primitive concrete.” The northern portion of the acequia, which flows from the east side of the river towards the mission, was restored and reopened in late 2011.

Espada Dam, Acequia, and Aqueduct –Construction of the Espada Acequia began shortly after the mission’s relocation from East Texas in 1731. It began at a dam “spanning the [San Antonio] river midway between the missions San José and San Juan.” Espada dam is the city’s only Spanish Colonial dam that is still functional. It is “constructed of limestone and lime mortar” and is “noted for its unique reverse curve design.” Shortly after the acequia’s construction, it became necessary to “construct an aqueduct to carry the water over Piedras (Six-Mile) Creek” approximately 1.49 miles from the dam. The aqueduct also still exists, and it has been described as the system’s most remarkable feature. The acequia continues south from the aqueduct to the mission, and further south a total distance of approximately 3.2 miles (Cox 2005). Visitors can still access the dam, acequia, and aqueduct in the San Antonio Missions National Historical Park (Link 10).

San Pedro Acequia/Ace quia Principal –In addition to the mission acequia systems, another acequia was constructed to serve the civilian and military populations of San Antonio beginning in 1718. The ditch, known as the Acequia Principal or the San Pedro Acequia, was expanded further after the arrival of the Canary Islanders in 1731 to serve their agricultural lands south of the settlement. Specifically, the land allotted to the settlers for agricultural purposes was located “south of the villa between the [San Antonio] river and …[San Pedro] creek down to the confluence of the streams.” To irrigate this area, the colonists planned to extend the existing acequia “from San Pedro Springs southward” between the San Antonio River and San Pedro Creek “returning to the river just prior to its confluence” with the creek. The expanded ditch was in operation by 1734. By that year, it was approximately four miles long and irrigated “approximately 400 acres below the villa” including “the new lands of the Islanders and other citizens.” It was also used by residents of the presidio, making the presidio’s ditch obsolete within a few years. By the mid-nineteenth century, the San Pedro Acequia was no longer in use for irrigation. Instead, it served as the city’s main source of drinking water.

In addition to these acequias constructed to serve the missions and the civilian settlement at Villa San Fernando, four additional acequias were constructed for the secular community. These included the acequia used by presidio residents, the Upper Labor Acequia constructed for East Texas Colonists (Adaesanos) who relocated to San Antonio in the late eighteenth century, and the Alazán and Valley Ditches in the nineteenth and twentieth centuries. The presidio’s acequia generally followed the route of portions of present day Romana and Navarro Streets. The ditch “formed the northern limits of the old city, the barrio del norte” (Cox 2005). It was later used as a return channel for the Upper Labor Acequia. It would have been approximately “4,000 feet in length and could have irrigated some 100 acres” surrounding the presidio” (Cox 2005). Contemporary accounts note evidence of the ditch was still visible as late as 1920, over 200 years after its original construction.

By the mid-1860s, San Antonio citizens began petitioning for the construction of additional acequias. Those still in use did not have the capacity to serve the city’s growing population. Though several private entities formed to promote both the expansion of existing acequias and the construction of new ditches, the city did not authorize any new construction until the 1870s. In 1874, the city council passed an ordinance allowing for the construction of two new acequias. The first, known as the Valley Ditch, had been in the planning stages since at least 1867. Upon completion in November of 1874, the ditch and its extension, known as Young’s Valley Ditch, irrigated over 2,000 acres.

The second acequia authorized by the city council was known as the Alazán Ditch. The 4.4-mile-long ditch extended from the Upper Labor acequia “near its beginning at San Pedro Springs” and headed west and south. As originally constructed, it was intended to irrigate over 6,000 acres in western San Antonio, and though it was functioning by the end of 1875, like its counterpart the Valley Ditch, problems with the Alazán ditch “continued to plague the city” (Cox 2005). Though archeological excavation of these later ditches indicated they were much more elaborate than their Spanish Colonial counterparts, they were not as well engineered. Eventually both projects would be condemned as “foolish and extravagant experiment[s],” and the City of San Antonio adopted a formal waterworks system in July of 1878 (Cox 2005).

From this point forward, the city’s historic acequias were “left to function primarily as a storm drainage system.” Even in this capacity, the structures were limited as they did not serve newer areas of the city and “lacked the capacity to handle runoff from major storms.” Nevertheless, they remained part of the city infrastructure for another 15 years before many of the main ditches began to be closed. By the middle of 1905, the Alamo Madre Ditch had been closed. The San Pedro Ditch was closed seven years later, and by 1913 “the urban acequias were all closed, though a few downtown portions of the Alamo and San Pedro acequias were still being used as storm drains” (Cox 2005). In contrast, the rural San Juan and Espada systems continued to be used well into the twentieth century. They were being operated by private ditch companies rather than by the city, and were therefore immune to the municipally mandated closures.

Overall, the acequias had a profound impact on the layout of the city of San Antonio and on early economic and community development in the area. Instead of a grid system of roads in the vicinity of the missions and the acequias, initial road placement and property divisions are oriented about the acequias. Archaeological work in the city has located many preserved sections of the system, including the major canals listed above as well as smaller lateral ditches that directed water to specific pieces of land (Baker et al 1974).


  • Baker, T. Lindsay, James D. Carson, and Joseph Minor

    1974 - Historic American Engineering Record, The Acequias of San Antonio, HAER No. TX-1, Prepared for the National Park Service, Department of the Interior, Washington, D.C.

  • Cox, I. Waynne

    2005 - The Spanish Acequias of San Antonio, San Antonio, Texas, Maverick Publishing Company.
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