Lower Crystal Springs, also known as Crystal Springs Reservoir, is a gravity dam located in San Mateo, California, along the San Mateo Creek. Built in 1888, this dam serves as a crucial water supply source for the region, with a storage capacity of 57,910 acre-feet and a surface area of 1,323 acres. The dam stands at a height of 149 feet, with a hydraulic height of 138.8 feet, making it an essential infrastructure for water resource management in the area.

Managed by the local government, Lower Crystal Springs is regulated and inspected by the California Department of Water Resources for safety and compliance. Despite its high hazard potential, the dam's condition assessment in 2017 deemed it satisfactory, ensuring its continued functionality and security. With a history dating back over a century, Lower Crystal Springs remains a vital component of the region's water supply infrastructure, highlighting the intersection of historical significance and modern-day climate resilience efforts.

With its proximity to San Francisco and under the jurisdiction of San Mateo County, Lower Crystal Springs plays a key role in water management and climate adaptation strategies in the region. The dam's design and construction reflect a commitment to sustainable water supply practices, while its regular inspections and emergency preparedness measures ensure the safety of surrounding communities. Lower Crystal Springs stands as a testament to the intersection of water resource management, climate resilience, and historical preservation in California's evolving landscape.