Soon after Mission Santa Barbara was established in 1786, its growing population increased demand for water for domestic and agricultural use as well as milling and tanning, and the severe droughts of 1794 and 1795 led to creation of a water transport and storage system. This was the first major effort to bring an abundant and reliable water supply to the Santa Barbara community. Using a design created by Franciscan Padres, Native American laborers from the Barbareño Chumash built a system that drew from nearby year-round streams. The first reservoir at the Mission was constructed in 1806, followed by Mission Dam in 1807 and a second dam in Rattlesnake Canyon in 1808. Mission Dam, built 1½ miles from the Mission at 750 feet elevation in Mission Creek, formerly Pedregosa Creek, stored water by impounding it upstream with wooden slats placed in grooves at the floodgate. Rattlesnake Dam, 2¼ miles from the Mission at 1,050 feet elevation, was built not to store water but to divert it into the Rattlesnake Canyon Aqueduct. Water moved downhill by gravity through two aqueducts to the Mission, and although they ran parallel in places, they never merged. The aqueducts required constant maintenance to remain free of debris and sediment. Water from the Mission Canyon aqueduct could flow into a large storage reservoir for orchards and gardens or pass through a charcoal-filled filter house into a small reservoir for residential use, a fountain, and the lavandería, a place for washing clothes. Water from the Rattlesnake Canyon aqueduct, also called the Mill Aqueduct, filled a small reservoir that powered the grist mill or could be diverted into the filter house or larger storage reservoir. Mission Dam was constructed with lime mortar and alternating layers of small and large unmodified river cobbles collected from the creek, measured 110 feet across, 23 feet tall on the downstream side, and 18 feet thick, and was placed on stable protruding sandstone bedrock; its surface was covered with fired red clay tiles called ladrillos, and a 60-foot by 10-foot masonry extension to the northwest helped prevent water from cutting too deeply into the hillside at the end of the dam. Water passed through the dam by an internal flume, likely later hidden by a cement intake box installed by the Mission Water Company, and archaeological studies indicate that water probably traveled from the dam to the aqueduct by a cobble bridge that later washed out. After the Mission era ended in the 1830s, the waterworks remained in good repair into the 1840s but had deteriorated by the 1870s. In 1872 the Mission Water Company purchased the system and made several changes that bypassed the aqueduct, including a cement intake box, filter box, and an 8-inch steel pipe; water entering the intake box was filtered by wire mesh screens, moved by pipe to the filter box for sediment removal, and then flowed through the pipeline to the storage reservoir at the Mission. Use of most of the system ended after the floods of 1913-14, and in 1940 the Santa Barbara Botanic Garden acquired the property containing Mission Dam and portions of the aqueduct.
