The First Crystal Springs Bridge

The Lower Crystal Springs Dam across San Mateo Creek went up in 1888, and the first bridge on top of it opened soon after.

The narrow wood-planked crossing easily accommodated the horse-drawn vehicles of the time, and members of the Association of Civil Engineers soon turned out in force to inspect and celebrate.      

The new dam secured an additional welcome supply of more fresh, clean Peninsula water for thirsty San Francisco to the north. And the inventive gravity-arch structure itself, built of staggered interlocking concrete blocks, has lasted without fail ever since. It survived unimpaired the next two major earthquakes of 1906 and 1989.

Lower Crystal Springs Dam stands 149 feet tall on a 176-foot-wide base. The SFPUC recently upgraded it to ensure safe discharge of reservoir water during high rain periods. The more

contemporary bridge of the 1920s was removed just beforehand, with plans to construct a more seismically stable one in its place. 

The new 21^st-century bridge opened this past January 11.  

Today Upper and Lower Crystal Springs operate as one reservoir and have a combined capacity of 22.5 billion gallons of water. The stored stream runoff, rainfall and surplus Sierra Nevada waters are continually drawn on as an essential local supplement to the Hetch Hetchy drinking water we serve throughout the Peninsula and San Francisco.