Olivenhain Reservoir, located in San Diego County, California, was constructed in 2003 by the city of Encinitas. The reservoir's primary purpose is to store imported water from the Colorado River and Northern California for use by the city's residents. The reservoir has a capacity of 24,000 acre-feet and is primarily filled by water from the San Diego County Water Authority. Additionally, the reservoir receives water from local surface flow and snowpack providers, including the San Dieguito River and the San Elijo Lagoon. The reservoir also supplies water for agricultural use in the surrounding area. Recreational activities, such as fishing and boating, are allowed on the reservoir with proper permits. The Olivenhain Reservoir serves as a vital water source for the region's residents and supports the local agriculture and recreational industries.