Arroyo Mocho Creek Crossing

The Arroyo Mocho Creek Crossing is located in the lower end of the Arroyo Mocho Canyon in Livermore, California. A concrete ford creek crossing was constructed across the stream at the Arroyo Mocho Shaft Road and was used by the Lawrence Livermore National Laboratories to access the Arroyo Mocho Pump Station, the primary water supply for the laboratories. The creek crossing was a complete barrier to both steelhead and resident trout migration. Sherwood (operating as Fall Creek Engineering) led a multi-disciplinary team of engineers, biologists, geomorphologists, and hydrologists to develop restoration plans and specifications for a clear span bridge.  The project involved the development of a biological assessment, a geomorphic assessment and hydraulic analysis and preparation of engineering design plans and specifications for the restoration of the stream, the removal of the concrete ford, and the design of a new clear span steel truss bridge to provide year-round access to the pump station.  The project entailed the removal of the concrete ford, the reshaping of the stream channel, the installation of an 80-foot clear span bridge and concrete abutments, and the restoration of approximately 190 lineal feet of channel upstream of the crossing to establish a new stream grade and alignment.  The newly restored reach included 4 vortex boulder weirs constructed to provide year-round fish passage and grade control.