Old Mission Dam ruins (Mission Trails Regional Park)

Old Mission Dam was constructed in 1813–1814 to impound the San Diego River and supply water to Mission San Diego de Alcalá and is one of California’s earliest European-built waterworks. Sections of the original stone masonry and earthen dam survive today as ruinous remains within Mission Trails Regional Park and the site is designated a National Historic Landmark. Archaeological and preservation studies have documented its construction methods and subsequent deterioration, and the ruins are interpreted by park signage and the nearby visitor center.