No roadside marker notes its historic significance, but a rural hilltop just off state Route 76 near Fallbrook is where the story of modern San Diego County begins. A few feet underground is a gravity-flow pipeline delivering water from the Colorado River through Lake Skinner in Riverside County, then to San Vicente Reservoir near Lakeside. South of the hilltop connection is where the San Diego County Water Authority takes ownership of the region’s historic Pipeline 1, along with four other major concrete and steel veins that send water coursing to cities and water agencies throughout the San Diego region.