In October 2000, Caltrans started driving test piles for the San Francisco-Oakland Bay Bridge, seismic safety project. Underwater noise pressure waves radiated from the impact driving activity, resulting in harassment and harm to listed fish. At that time, Caltrans, the Federal Highway Administration, and the National Marine Fisheries Service (NMFS) realized the need to address potential hydroacoustic impacts to fish and other aquatic species, related to pile driving activities. Due to the need to develop information and research on effects criteria for fish, in 2004, Caltrans in coordination with Washington DOT, Oregon DOT, Federal Highways Administration (FHWA), NMFS, California Department of Fish & Wildlife (CDFW) & U.S. FWS, established the Fisheries Hydroacoustic Working Group (FHWG). In June 2008, the FHWG agreed on both peak and accumulative thresholds for fish exposed to pile driving operations.
Caltrans has developed Technical Guidance for Assessment and Mitigation of the Hydroacoustic Effects of Pile Driving on Fish, Appendix A of the Guidance Manual includes the Compendium of Hydroacoustic Data.