The Lower Crystal Dam and the roadway that runs over it have undergone major improvements, which were formally unveiled and celebrated during a Friday ceremony outside of Redwood City in San Mateo County.
The multi-faceted project includes critical safety and water-capacity improvements to the dam, and provides new travel opportunities on the bridge and adjacent recreational trails.
The Lower Crystal Springs Dam crosses San Mateo Creek, forming the Upper and Lower Crystal Springs reservoirs. The dam is part of the San Francisco Public Utilities Commission's Hetch Hetchy Regional Water System.
The structure is a concrete gravity arch dam, engineered in a way that revolutionized the dam and concrete industries and served as a model for Hoover Dam.
From 2010 to 2011, before the SFPUC could begin its $35 million in renovations, San Mateo County's Department of Public Works removed the original 1920s-era bridge from the top of the dam. During that same time, the
SFPUC began work to double the width of the spillway to 200 feet and raise the parapet wall on top of the dam by 9 feet. Construction of the dam finished in December 2012.
Skyline Boulevard, also known as Highway 35, runs over the dam and has been closed to auto traffic between Crystal Springs Road and Bunker Hill Drive as the related-but-separate dam and road projects were being done.
Construction of the $13.1 million bridge started in February 2016.
The new bridge includes a separate section for Crystal Springs Regional Trail users to connect to a new "South of Dam" trail section completed in 2015.
San Mateo County Parks built the new trail segment, and PG&E relocated high-voltage transmission lines to the new bridge's underside.
The interconnected projects were made more complicated by their location in an environmentally sensitive area that is home to the dusky-footed wood rat, the California red-legged frog and the San Francisco garter snake.
"There's no question everyone involved had a lot to contend with on the road to success, but I'm proud to say we did it and thankful for the patience of the community, which has been so eager to see it complete," said San Mateo County Public Works Director Jim Porter.