The unreliability of the San Diego River compelled the Franciscan fathers to construct the area's first dam in 1813 to conserve drinking and irrigation water for the Mission San Diego de Alcal . This water-driven circumstance continued and expanded in the ensuing American era. Lacking a reliable water source at the turn of the 20th century, San Diego County was destined to experience modest growth. The region's semiarid conditions, cyclical droughts,...