San Andreas, also known as San Andreas Lake, is a significant water resource located in San Mateo, California. Owned by the local government, this dam serves as a vital water supply infrastructure, completed in 1870 and standing at a height of 107 feet. With a storage capacity of 19,027 acre-feet and a surface area of 550 acres, San Andreas plays a crucial role in providing water to the surrounding area.

Managed and regulated by the California Department of Water Resources (DWR) and Safety of Dams, San Andreas is subject to regular inspections to ensure its safety and maintenance. Despite being classified as having a high hazard potential, the dam is currently in fair condition. The last inspection in December 2020 revealed its compliance with safety standards, with an emergency action plan in place and regular assessments of its risk management measures. With its location on Tr San Mateo Cr and its proximity to the city of San Mateo, San Andreas is a key player in the water infrastructure of the region.

Enthusiasts of water resources and climate will find San Andreas to be a fascinating case study in dam management and water supply infrastructure. With its historical significance, structural design, and regulatory oversight, this dam exemplifies the complex interplay between human engineering and natural resources. As one of the critical elements in California's water supply system, San Andreas stands as a testament to the ongoing efforts to balance water management, safety regulations, and environmental sustainability in the face of changing climate conditions.