Spanish missionaries introduced irrigation in San Bernardino Valley, opening the way to settlement. In 1819, Franciscan Fathers engineered and Native Americans dug this first ditch, or zanja. It supported the San Bernardino Estancia, the Rancho San Bernardino, then pioneer ranches and orchards, and finally Redlands' domestic water supply. The Zanja was placed on the National Register of Historic Places in 1977.