Habitat Equivalency Analysis
Habitat Equivalency Analysis is one among a set of methods for quantifying injury and damages, developed during Natural Resource Damage Assessment processes defined under the federal Oil Pollution Act and Comprehensive Environmental Response, Compensation, and Liability Act. HEA uses units called "Discounted Service Acre Years" to compare between a period and area of injury caused by toxic contamination, and a period and area of restoration. The method considers the relative importance of each area to a set of target species. "Service Acres" are a "weighted acre" approach, where the area affected is multiplied by a number reflecting its habitat value. Discounting is applied based on economic theory that suggests that current service has greater value than service at some point in the future, which also solves the mathmatical problem of estimating habitat services from restoration, over long periods of time. Ultimately HEA is an estimation tool, used for the negotiation of compensation for illegal releases or other damages. The use of HEA has expanded over time to be used for quantifying increments of habitat injury caused by development.
- File:Idanza 2001 habitat value and time to recovery.pdf and File:Wolotira 2002 defining natural resource injury.pdf provide some of the earliest use of HEA for quantifying injury at the Hylebos Waterway in Commencement Bay in the historical Puyallup Delta.
- File:Ehinger et al 2015 nearshore habitat value HEA.pdf describes the use of HEA for quantifying shoreline modification in Puget Sound.