California Department of Transportation

Division of Environmental Analysis (DEA) LINKS

square icon

Adobe Acrobat Reader is required to view and print PDF files. Adobe Acrobat is required to edit online forms and save them to your computer.

Get Acrobat Reader Image


Last Updated: Thursday, November 19, 2015 11:41 AM

Fisheries - Hydroacoustic

The California Department of Transportation (Caltrans) in coordination with the Federal Highways Administration (FHWA) and the departments of transportation in Oregon and Washington, established a Fisheries Hydroacoustic Working Group (FHWG) in order to improve and coordinate information on fishery impacts due to underwater sound pressure caused by in-water pile driving. In addition to the above transportation agencies, the FHWG is composed of representatives from NOAA Fisheries (Southwest), NOAA Fisheries (Northwest), U.S. Fish and Wildlife Service, California Department of Fish and Game, and the U.S. Army Corps of Engineers. The FHWG is supported by a panel of hydroacoustic and fisheries experts who have been recommended by the FHWG members. A Steering Committee oversees the FHWG and is composed of managers with decision-making authority from each of the members' organizations.

The goal of the Working Group is to reach agreement on: 1) The nature and extent of knowledge about the current scientific basis for underwater noise effects on fish, 2) Interim guidelines for project assessment, mitigation, and monitoring for effects of pile-driving noise on fish species, and; 3) Future scientific research needed to satisfactorily resolve uncertainties regarding hydroacoustic impacts on fish species.

Effects of Sound on Fish

In an effort to address hydroacoustic impacts early in the project delivery process, "Technical Guidance for Assessment and Mitigation of Hydroacoustic Effects of Pile Driving on Fish", has been updated. The Compendium of Hydroacoustic Data is available in Appendix 1 of the Manual. Please continue to work with appropriate project delivery team members and resource agency staff to address issues specific to your project and to check the fish hydroacoustic website for changes as science and engineering evolve to further address hydroacoustic issues. For biological information and assistance regarding hydroacoustic impacts please contact at 707-445-6627, or at (916) 653-8566

The Fisheries Hydroacoustic Working Group (FHWG) have developed the Underwater Noise Monitoring Template for use as a general monitoring report outline and to provide guidance for monitoring and reporting underwater sound levels generated during impact pile driving.

When submitting a Biological Assessment that includes a hydroacoustic evaluation, NMFS requires use of the NMFS Pile Driving Calculator to assess the potential impacts of pile driving. The NMFS excel spreadsheet requires the use of data from driving similar piles in similar substrate. The appendix of the Hydroacoustic Guidance Manual includes a Compendium of past hydroacoustic projects, for this purpose. Follow the instructions on the first sheet of the NMFS calculator and make sure to include comments in the notes regarding the project(s) selected for comparison and why they were chosen for comparison. Copies of the spreadsheet should be included as attachments in your BA, for use and review by NMFS staff as they are writing the Biological Opinion.

Design of bridge foundations in seismically active zones has necessitated the use of steel piles. In addition to the superior structural properties of steel piles under seismic loading, steel piles address a number of other attendant foundation issues. Steel piles are cost effective (concrete pile cast within a steel shell), minimize bridge foundation scouring, armor the structural elements from inadvertent collisions with marine traffic, and minimize the "footprint" within the aquatic environment. Aging transportation infrastructure and the need to service transportation demand have increased the number of bridge projects that require pile driving. As a consequence of larger piles and required retrofitting activities, pile driving for bridge projects has resulted in the observed death of fish in San Francisco Bay.

Human-related activities have historically contributed to the decline of fish populations and resulted in the listing of fish species under the federal Endangered Species Act (ESA). Nearly every estuary and major stream in California, Oregon, and Washington provide habitat for one or more listed fish species and species managed under the Essential Fish Habitat (EFH) provisions of the Magnuson-Stevens Act (MSA). The observed death of fish associated with driving large diameter (greater than 5 foot) steel shell piles has elevated the public and resource agency concern relative to effects on listed species populations. Required development of minimization measures to protect fish species listed under the federal Endangered Species Act (ESA) has resulted in costly project delays and increased project implementation costs for departments of transportation in California, Washington, and Oregon.

As part of this effort, Caltrans retained Dr. Arthur Popper and Dr. Mardi Hastings to prepare a report evaluating currently available information and to recommend interim impact thresholds. This report was reviewed by the FHWG at a meeting in June 2004. In response to comments received at this meeting Dr. Popper and Hastings revised the report and presented it to the group in December 2004. In August 2005 an appendix in the report was revised to provide additional clarification and to correct an error in an equation. Click the following link to view the final report entitled "The Effects of Sound on Fish," [January 28, 2005].

"Interim Criteria for Injury of Fish Exposed to Pile Driving Operations: A White Paper," [May 14, 2006] presents science-based, interim noise exposure criteria for the onset of direct physical injury in fish exposed to the impact sound associated with pile driving. It was authored by Dr. Arthur Popper, Dr. Thomas Carlson, Anthony Hawkins, Dr. Brandon Southall and Dr. Roger Gentry on request of the Fisheries Hydroacoustic Working Group in January 2006.

"Update on Recommendation for Revised Interim Sound Exposure Criteria for Fish during Pile Driving Activities," [December 21, 2007] presents the newest science-based, interim noise exposure criteria for the onset of direct physical injury in fish exposed to the impact sound associated with pile driving. It was authored by Dr. Thomas Carlson, Dr. Mardi Hastings, and Dr. Arthur Popper. In this memo, they propose criteria for each of three different effects on fish; 1) hearing loss due to temporary threshold shift, 2) damage to auditory tissues, and 3) damage to non-auditory tissues. These criteria vary due to the mass of the fish and if the fish is a hearing specialist or hearing generalist. In preparing this update, Dr. Mardi Hastings summarized information from some current studies in a report titled "Calculation of SEL for Govoni et al. (2003, 2007) and Popper et al. (2007) Studies."

A response "Application of Revised Interim Pile Driving Impact Criteria," [December 21, 2007] to the Dec 21, 2007 memo was developed by consultants Dave Buehler and Rick Oestman of Jones & Stokes and James Reyff of Illingworth & Rodkin addressing the implications of these new criteria to Caltrans projects. It recommends that Caltrans generally use the criterion from the Dec 21, 2007 Revised Criteria Memo of 206 dB-peak and 189 dB-SEL accumulated over a day for the types of fish we commonly deal with.

The FHWG met in June 2008 and agreed to a new interim criteria for injury to fish from pile driving noise. This new criteria is to be used as of August 2008 until further notice. This is a dual criteria including a peak level of 206 dB (peak) AND a cumulative SEL level of 187 dB (SEL) for fish 2 grams and heavier OR a cumulative SEL of 183 dB (SEL) for fish smaller than 2 grams.

Ongoing Research Work

Caltrans is also involved in the National Cooperative Highway Research Program (NCHRP) study #25-28 "Predicting and Mitigation Hydroacoustic Impacts on Fish from Pile Installation" and the Transportation Pooled Fund Program Study "Structural Acoustic Analysis of Piles."

Please send questions or corrections regarding this webpage to the Webmaster.