San Mateo County's Crystal Springs Dam receives National Historic Engineering Landmark status

Lower Crystal Springs Dam was completed in 1890, making the structure the first mass concrete dam of its kind in the nation and possibly the world. The dam was built by about 1,000 workers over a period of five years under the supervision of Chief Engineer Hermann Schussler using interlocking blocks of concrete. Each block was poured and cured before the neighboring block was poured, and the joints sealed with cement. 

Its design and innovative construction techniques revolutionized dam building and would go on to become standard practices, influencing the development of other notable concrete dams including the Hoover Dam in Nevada and the Grand Coulee Dam in Washington state.  

The dam, initially constructed by the Spring Valley Water Company and now owned and operated by the San Francisco Public Utilities Commission, has also survived two significant earthquakes — one in 1906 and the Loma Prieta Earthquake of 1989 — a significant feat given that it sits just 1,000 feet from the San Andreas Fault. 

These collections of facts are key reasons for why the American Society of Civil Engineers has decided to honor the Lower Crystal Springs Dam as a National Historic Engineering Landmark. The dam joins the Golden Gate Bridge, the San Francisco-Oakland Bay Bridge, and the Alvord Lake Bridge as one of only four projects to receive the honor in Northern California, and is one of 14 projects in the state. A ceremony presenting the honor was held on the dam between rain showers Wednesday, Dec. 6.

“This dam is more than just a structure. It symbolizes the growth and resilience of our community over 100 years,” Rami Selim, president of the ASCE San Francisco chapter, said. “Together we pledge to preserve this piece of our history for future generations.” 

Tim Paulson, president of the San Francisco Public Utilities Commission, noted the significant role Crystal Springs Dam has played in the region. It helped create the Crystal Springs Reservoir, which provides drinking water to about a million people in northern San Mateo and San Francisco counties and has the capacity to hold up to 22.5 billion gallons of water when full. 

The dam has undergone improvements over the years. Its parapet was placed in 1891 and the dam was raised another 25 feet in 1911. The bridge atop the dam has been replaced multiple times, most recently in 2018, opening to the public in 2019. 

“We invest in our infrastructure. We maintain our infrastructure. We’re not going to be like Flint, Michigan. We’re going to maintain our valuable resources and what is needed for our residents of our areas to have the water they need,” Paulson said. “This dam continues to be a masterpiece of civil engineering we have to have.” 

Surrounding the dam and reservoir is thousands of acres of open space managed in partnership between SFPUC and the San Mateo County Parks Department including the Sawyer Camp Trail north of the lower dam and the Crystal Springs Regional Trail just south. County Parks Director Nicholas Calderon lauded SFPUC as an upstanding partner during the event, sharing that the department feels fortunate to have recreational facilities that highlight the historic landmark. 

“The Crystal Springs Dam and Bridge are beloved landmarks offering scenic routes for recreational activities and critical connections for motorists, pedestrians and bicyclists,” Calderon said in a press release. “We here in San Mateo County have always known it is special and we’re thrilled it now gets national recognition too.”