Olivenhain Dam, Hydroelectric power station and gravity dam in San Diego County, United States

Olivenhain Dam is a gravity dam constructed from roller-compacted concrete in San Diego County that stores water from Lake Hodges for regional supply. The structure connects to the Second San Diego Aqueduct and serves as a key water source for the San Diego area.

Construction took place between 1998 and 2003, making it the first roller-compacted concrete dam built in California. This construction method represented an advance in dam engineering and influenced future water infrastructure projects in the state.

The surrounding Elfin Forest Recreational Reserve offers outdoor activities where visitors can learn about local water resources and ecosystems. Walking through these trails, people gain insight into how this structure supports the region's daily water needs.

The dam is accessible through hiking trails around the Elfin Forest Recreational Reserve with viewpoints of the water storage facility. Visitors should wear sturdy shoes and bring plenty of water, especially during warmer months.

Olivenhain Dam is paired with Lake Hodges as the lower reservoir of a pumped-storage plant: two 20 MW Francis turbines move water through a 2 km conduit, 3 m in diameter, between levels 235 m apart. In 2017 the plant generated 58 million kWh for peak loads, connected to the grid by a 69 kV line.