Section 7 Effects Analysis: Acoustics in the Greater Atlantic Region
Guidance for action agencies on how to address acoustics in their Effects Analysis.
Multi-Species Pile Driving Calculator
This calculator was developed by NOAA Fisheries Office of Protected Resources as a tool for assessing the potential effects to ESA-listed species exposed to elevated levels of underwater sound produced during pile driving activities. This calculator is most appropriate for coastal or inland pile driving projects (not pile driving associated with wind farm construction).
Multi-Species Pile Driving Calculator (Excel, last updated September 2025)
DISCLAIMER: NOAA Fisheries has provided this spreadsheet as an optional tool to provide estimated effect distances (i.e., isopleths) where pile driving thresholds may be exceeded. Results provided by this spreadsheet do not represent the entirety of the comprehensive effects analysis, but rather serve as one tool to help evaluate the effects of a proposed action on protected species and make findings required by NOAA’s various statutes. Input values are the responsibility of the individual user. NOAA Fisheries does not take any responsibility for the interpretation of the results by non-NOAA Fisheries users or for misuse or modification of the spreadsheet.
The document below provides additional step-by-step guidance on the use of the Multi-Species Acoustic Calculator. We encourage project managers and other users to take the time to carefully review this guidance, in addition to the introductory information included in the calculator, as they get familiarized with the use of this new tool and its interpretation.
Acoustic Tool Guidance (PDF, 52 pages)
In order to obtain more accurate estimates, the new acoustic calculator requires project managers to provide additional parameters such as estimated strikes per pile, and the number of piles installed per day. We encourage project managers to coordinate with applicants and/or non-federal partners/subcontractors to obtain these parameters. For cases in which this is not possible, we at GARFO have put together in-house estimates that could be used to supplement this information. These estimates can be accessed here:
GARFO Pile Driving Parameters (Caltrans 2020; Excel)
For further technical guidance on the acoustic effects analysis, please see Marine Mammal Acoustic Technical Guidance & Other Acoustic Tools.
Writing Your Justification
With the implementation of the new HQ noise tool and its associated calculations and assumptions, ensonified area measurements of where noise effects may be experienced by ESA listed species may change. As a result it is possible that projects that previously fit under the current NAD programmatic may need some additional justification. With the GARFO-specific noise tool, in most circumstances where we were able to concur with an action under the Verification Form process, a physical zone of passage was maintained allowing ESA listed species appropriate buffer zones outside of ensonified areas. In many cases, this may still be true with the updated HQ noise tool. However, in instances where the new HQ noise tool estimates that an entire waterbody is now ensonified, we recommend next considering the temporal component of the noise-producing activities and effects. Specifically, the analysis should determine whether the noise-producing activities are constant (i.e., 24 hr / day) duration or whether there will be times of quiet where fish passage can now continue through areas that were previously ensonifed when the noise producing activities were taking place.
The following situations and examples should be considered by the action agency when verifying if their project fits within the existing NAD programmatic analysis:
- The area is completely ensonified when ESA listed species are not expected to be present. (e.g., activity occurs in the marine environment during winter months where sea turtles, sturgeon and whales do not seasonally occur, etc.)
- The area is completely ensonified and ESA listed species are transient in the action area. Because the noise-producing activity occurs for XX hours per day, a temporal zone of passage is still maintained. (e.g., activity occurs in-river or estuary where no overwintering aggregations, spawning areas, etc. are located, and opportunistically foraging sturgeon pass through at varying intervals, etc.)
- The project employs non-invasive diver sweeps or observation techniques (no trawling) to ensure that ESA-listed species are not within the temporarily ensonified area before commencing any noise-producing activity.
If after using the HQ noise tool it is determined that none of the situations above apply (i.e., no temporal or spatial zones of passage or use of management measures to minimize or avoid impacts) then it is likely that the project is better suited for individual ESA S7 consultation rather than processing through the NAD programmatic.
Example Analysis - Temporal
Exposure to underwater noise levels of 206 decibels (dB) peak and 187 dB cumulative sound exposure level (cSEL) can result in injury to sturgeon, and levels of 230 dB Peak and 184 dB cSEL can result in injury to sea turtles. In addition to the “peak” exposure criteria that relate to the energy received from a single pile strike, the potential for injury exists for multiple exposures to noise over a period of time; this is accounted for by the cSEL. The cSEL is not instantaneous maximum noise levels but represents a measure of the accumulated energy over a specific period of time (e.g., the period of time it takes to install a pile).
During the proposed [type of hammer] hammering of the __-inch diameter [type of piles] piles, the maximum distance to the 206 dB peak underwater noise level is expected to be __ meters, and the maximum distance to the 187 dB cSEL isopleth is expected to be __ meters for sturgeon. To be exposed to potentially injurious levels of noise, a sturgeon would need to be within [distance to the 206 dB peak isopleth] of the pile for a single strike or remain within [distance to the 187 dB cSEL isopleth] of the pile being driven for a prolonged time period (i.e., the duration of pile driving in a day). This is unlikely to occur because sturgeon are extremely unlikely to be within [distance to the 206 dB peak isopleth] of the pile when pile driving begins and are expected to avoid areas where noise is above 150 dB, which is an area estimated to extend __ meters from the pile.
For sea turtles, the maximum distance to the 230 dB peak is expected to be __ meters, and the maximum distance to the 184 dB cSEL isopleth is expected to be __ meters. To be exposed to potentially injurious levels of noise, sea turtles would need to be within [distance to the 230 dB peak isopleth] of the pile for a single strike or remain within [distance to the 184 dB cSEL isopleth] of the pile being driven for a prolonged time period. This is unlikely to occur because sea turtles are extremely unlikely to be within [distance to the 230 dB peak isopleth] of the pile when pile driving begins and are expected to avoid areas where noise is above 175 dB RMS behavioral threshold, which is an area estimated to extend __ meters from the pile. Given that the time to drive the piles will be short and the species that will be present are transient, the effects to listed sturgeon and sea turtles that may be exposed to pile driving noise (i.e., disruptions of normal behaviors for a short period of time to avoid pile driving noise) would be too small to be meaningfully measured or detected and are insignificant.
Behavioral effects, such as avoidance or disruption of foraging activities, may occur in sturgeon exposed to noise above 150 dB RMS and to sea turtles exposed to noise above 175 dB RMS. Considering all the pile driving activities, it is expected that underwater noise levels would be below 150 dB RMS for sturgeon at distances beyond a maximum of __ meters during impact hammering. Noise levels would be below 175 dB RMS for sea turtles beyond a maximum of __ meters for impact hammering. It is reasonable to assume that a sturgeon or sea turtle, upon detecting underwater noise levels at or above these thresholds, would modify its behavior such that it redirects its course of movement away from the ensonified area surrounding the activity. Given that the time to drive the piles will be short and the species that will be present are transient, the effects of underwater noise on ESA species would be too small to be meaningfully measured or detected and would be insignificant.
Example Analysis - Distance
Exposure to underwater noise levels of 206 decibels (dB) peak and 187 dB cumulative sound exposure level (cSEL) can result in injury to sturgeon, and levels of 230 dB Peak and 184 dB cSEL can result in injury to sea turtles. In addition to the “peak” exposure criteria that relate to the energy received from a single pile strike, the potential for injury exists for multiple exposures to noise over a period of time; this is accounted for by the cSEL. The cSEL is not instantaneous maximum noise levels but represents a measure of the accumulated energy over a specific period of time (e.g., the period of time it takes to install a pile). The farther a fish or sea turtle is away from the pile being driven, the more strikes it must be exposed to in order to accumulate enough energy to result in injury. At some distance from the pile, the organism is far enough away that, regardless of the number of strikes it is exposed to, the energy accumulated is low enough that there is no potential for injury.
During the proposed [type of hammer] hammering of the __-inch diameter [type of piles] piles, the maximum distance to the 206 dB peak underwater noise level is expected to be __ meters, and the maximum distance to the 187 dB cSEL isopleth is expected to be __ meters for sturgeon. To be exposed to potentially injurious levels of noise, a sturgeon would need to be within [distance to the 206 dB peak isopleth] of the pile for a single strike or remain within [distance to the 187 dB cSEL isopleth] of the pile being driven for a prolonged time period (i.e., the duration of pile driving in a day). This is unlikely to occur because sturgeon are extremely unlikely to be within [distance to the 206 dB peak isopleth] of the pile when pile driving begins and are expected to avoid areas where noise is above 150 dB, which is an area estimated to extend __ meters from the pile.
For sea turtles, the maximum distance to the 230 dB peak is expected to be __ meters, and the maximum distance to the 184 dB cSEL isopleth is expected to be __ meters. To be exposed to potentially injurious levels of noise, sea turtles would need to be within [distance to the 230 dB peak isopleth] of the pile for a single strike or remain within [distance to the 184 dB cSEL isopleth] of the pile being driven for a prolonged time period. This is unlikely to occur because sea turtles are extremely unlikely to be within [distance to the 230 dB peak isopleth] of the pile when pile driving begins and are expected to avoid areas where noise is above 175 dB RMS behavioral threshold, which is an area estimated to extend __ meters from the pile. Given the small distance a sturgeon or sea turtle would need to move to avoid the ensonified area where injury could occur, the effects to listed sturgeon and sea turtles that may be exposed to pile driving noise (i.e., disruptions of normal behaviors for a short period of time to avoid pile driving noise) would be too small to be meaningfully measured or detected and are insignificant.
Behavioral effects, such as avoidance or disruption of foraging activities, may occur in sturgeon exposed to noise above 150 dB RMS and to sea turtles exposed to noise above 175 dB RMS. Considering all the pile driving activities, it is expected that underwater noise levels would be below 150 dB RMS for sturgeon at distances beyond a maximum of __ meters during impact hammering. Noise levels would be below 175 dB RMS for sea turtles beyond a maximum of __ meters for impact hammering. It is reasonable to assume that a sturgeon or sea turtle, upon detecting underwater noise levels at or above these thresholds, would modify its behavior such that it redirects its course of movement away from the ensonified area surrounding the activity. If any movements away from the ensonified area do occur, it is extremely unlikely that these movements would affect essential sturgeon or sea turtle behaviors, as the [type of waterway] is sufficiently wide enough ([width of the waterway]) to allow individuals to avoid the ensonified area while continuing to forage and migrate. Therefore, the effects of underwater noise on ESA species would be too small to be meaningfully measured or detected and would be insignificant.
Questions or suggestions?
- For basic information and questions about the use of this tool, contact Amy Scholik-Schlomer (amy.scholik@noaa.gov).
- For questions about your specific project or activity, contact the corresponding NOAA Fisheries PRD staff in your region.