Event Title

Habitat Equivalency Analysis (HEA): A tool for assessing marine impacts and mitigation requirements – the Sitka Airport Example

Presentation Abstract

Although several widely used approaches exist to assess function (quality) of freshwater wetlands, no such approach is available in the marine environment. A method was needed to assess ecological functions of marine habitats impacted by a planned safety expansion of the Sitka Airport. Project fill would eliminate 8.9 acres of marine habitat and alter the nature of 9.4 additional acres. We worked with permitting agencies to generate consensus to use an innovative application of the Habitat Equivalency Analysis (HEA) model to define project impacts and to evaluate alternative mitigation actions. The HEA model was developed by NOAA to assess the mitigation required to replace ecological functions and services lost due to an injury or impact. We first inventoried habitat types that would be impacted and developed a matrix to rate the degree to which each habitat type provides a suite of ecological functions. This “relative habitat function” for each habitat, multiplied by its area, was used to calculate project losses and gains in units of Habitat Functional Acres (HFA). Net present value of habitat in units of Discounted Functional Acre Years (DFAYs) was then calculated using actuarial principles of economic theory. The DFAY “debit” calculated for the project reflected temporal losses in habitat function, and the time to achieve full function of altered habitats. DFAYs lost to project construction (and gained from colonization of newly placed substrate) determined the net mitigation debit for lost ecological functions. After calculating DFAYs lost to airport expansion, we identified a suite of potential habitat protection, restoration, and enhancement actions within Sitka Sound that would compensate for some or all of the losses of marine habitat. Finally, we used HEA to determine the effectiveness of the selected mitigation action in compensating for those functions that would be lost. The objective of compensatory mitigation was met when the number of DFAYs provided by the mitigation action(s) equaled or exceeded the number of DFAYs lost.

Session Title

Session S-03F: Tools for Assessment and Implementation

Conference Track

Planning Assessment & Communication

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

1-5-2014 5:00 PM

End Date

1-5-2014 6:30 PM

Location

Room 6C

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

Text

Language

English

Format

application/pdf

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May 1st, 5:00 PM May 1st, 6:30 PM

Habitat Equivalency Analysis (HEA): A tool for assessing marine impacts and mitigation requirements – the Sitka Airport Example

Room 6C

Although several widely used approaches exist to assess function (quality) of freshwater wetlands, no such approach is available in the marine environment. A method was needed to assess ecological functions of marine habitats impacted by a planned safety expansion of the Sitka Airport. Project fill would eliminate 8.9 acres of marine habitat and alter the nature of 9.4 additional acres. We worked with permitting agencies to generate consensus to use an innovative application of the Habitat Equivalency Analysis (HEA) model to define project impacts and to evaluate alternative mitigation actions. The HEA model was developed by NOAA to assess the mitigation required to replace ecological functions and services lost due to an injury or impact. We first inventoried habitat types that would be impacted and developed a matrix to rate the degree to which each habitat type provides a suite of ecological functions. This “relative habitat function” for each habitat, multiplied by its area, was used to calculate project losses and gains in units of Habitat Functional Acres (HFA). Net present value of habitat in units of Discounted Functional Acre Years (DFAYs) was then calculated using actuarial principles of economic theory. The DFAY “debit” calculated for the project reflected temporal losses in habitat function, and the time to achieve full function of altered habitats. DFAYs lost to project construction (and gained from colonization of newly placed substrate) determined the net mitigation debit for lost ecological functions. After calculating DFAYs lost to airport expansion, we identified a suite of potential habitat protection, restoration, and enhancement actions within Sitka Sound that would compensate for some or all of the losses of marine habitat. Finally, we used HEA to determine the effectiveness of the selected mitigation action in compensating for those functions that would be lost. The objective of compensatory mitigation was met when the number of DFAYs provided by the mitigation action(s) equaled or exceeded the number of DFAYs lost.