Habitat Equivalency Analysis (HEA) is a means to determine the amount of compensatory restoration required to provide services that are equivalent to the interim loss of natural resource services following injury. The lost services are calculated from the time of injury through the recovery process. Recovery could be either via natural recovery or active restoration. The compensatory restoration services are calculated from the time of commencement through process of the chosen restoration. An injury to natural resources therefore involves a time component during which the ecological services that the resources provide are lost and over which the services of any compensatory restoration are gained. HEA uses a discounting procedure to account for asset valuation in that the total asset value is equal to the present discounted value of the future stream of all services from the natural resource or the compensatory resource.