San Diego Reservoir, located in Tuolumne, California, is a vital water resource structure that serves as a primary water supply for the region. Built in 1860, this earth dam stands at a height of 39 feet, with a hydraulic height of 35 feet, and a length of 155 feet. With a storage capacity of 40 acre-feet and a surface area of 5 acres, the reservoir plays a critical role in irrigation, recreation, and water supply for the area.

Managed by a public utility, San Diego Reservoir is regulated by the California Department of Water Resources (DWR) for safety compliance. The dam is inspected regularly, with the last assessment in February 2021 determining a satisfactory condition. While it has a significant hazard potential, due to its age and design, the structure is deemed to be in a satisfactory state, meeting regulatory guidelines and ensuring the safety of surrounding communities.

The reservoir, situated on Tr Mormon Cr river, is a key component of the water infrastructure in the region, providing essential resources for agricultural and domestic use. With its historical significance and ongoing maintenance, San Diego Reservoir continues to be a crucial asset in water management and climate resilience efforts in the area.