Field Trip to Mission Trails Regional Park.
See the Old Mission Dam (formerly called Padre Dam) Built by the Kumeyaay Indians for the Missionaries and the San Diego Mission. Completed in 1815.
From the Mission Trails Website (click above)
"While all of the California missions had some sort of water delivery system, the dam and flume constructed for the Mission San Diego de Alcala was by far the most ambitious. Built across the head of Mission Gorge, the 244-foot long, 13-foot thick, 13-foot wide dam was constructed of stone and cement on exposed bedrock, creating a permanent reservoir behind it. Water was released through gates and spillways into a 6-mile long gravity fed tile lined flume, down the gorge and Mission Valley, ending in a settling basin near the Mission. Construction was completed by 1815 and the padres had the water they needed."