09-30-2011 San Juan Acequia
On Tuesday September 27, 2011 after more than 30 years, the San Juan Acequia, part of the irrigation system built during the city’s Spanish colonial period, was given a new lease on life.
“Mission San Juan Capistrano’s acequia was probably begun about the time that the mission’s first huts were constructed on May 4,1731. However, progress on the mission-and probably on it’s acequia- was slow during the first ten years because of frequent Apache raids, by obstructionist tactics of then Governor Franquis de Lugo and by an epidemic in 1739.”¹
By February 1740 the San Juan Acequia was in operation. The fields were reported as newly planted in the spring of that year, and Father Fernández de Santa Ana wrote of the “five very abundant withdrawals from the river.”²
The acequia’s dam was constructed along the west bank of the river, almost directly opposite the present site of Mission San José. Branching from the west bank, it did not fully span the river channel but merely impounded a pool of water in order to raise the water to a level sufficient enough to allow flow into the deep intake created on the east bank.³ This type of structure is referred to as a weir, or diversion dam. Archival and archaeological evidence has shown that this type of construction was preferred during the Spanish period. Further down the acequia, a stone headgate was constructed to control the flow. The channel then continued southward on the east side of the river to the mission, a distance slightly exceeding 3 miles, ultimately emptying back into the river channel. An incredible feat of engineering to this day.
¹(Habig,Alamo Mission, 162)
²(B. Fernández de Santa Ana, “Fr. Benito Fernández de Santa Ana to Fr. Pedro del Barco, Febrauary 20, 1740,” Archivo General Nacional de Mexico, Historia, 25, 2: Oct. 1968, 199-206)
³(Hafernick, Cox and Fox, Archaeological Investigations of San Juan Dam, 6, 22)
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