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Last Updated: Monday, October 2, 2017 10:30 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 Wildlife, 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.

The FHWG have developed the Hydroacoustic Biological Assessment Guidance for use when preparing the consultation analysis.

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 ESA has resulted in costly project delays and increased project implementation costs for departments of transportation in California, Washington, and Oregon.

The FHWG met in June 2008 and agreed to an 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.

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