Rehabilitation of Highway 62 West, Crater Lake National Park, Klamath County, Oregon



In addition to determining the environmental consequences of the proposed action and alternatives, the 2001 NPS Management Policies and Director’s Order – 12: Conservation Planning, Environmental Impact Analysis, and Decision-making require analysis of potential effects to determine if actions would impair park resources. The fundamental purpose of the national park system, established by the Organic Act (1916) and reaffirmed by the General Authorities Act (1976), as amended, begins with a mandate to conserve park resources and values. National Park Service managers must seek ways to avoid, or minimize to the greatest degree practicable, adversely impacting park resources and values.

Congress has given National Park Service managers discretion, however, to allow impacts to park resources and values when necessary and appropriate to fulfill the purposes of a park, so long as the impact does not constitute impairment of the affected resources and values.

The prohibited impairment is an impact that would, in the professional judgment of the responsible National Park Service manager, harm the integrity of park resources or values, including opportunities that would otherwise be present for the enjoyment of those resources or values. An impact would be more likely to constitute an impairment to the extent that it has a major or severe adverse effect upon a resource or value whose conservation is:

  • necessary to fulfill specific park purposes identified in the establishing legislation or proclamation of the park,
  • key to the natural or cultural integrity of the park or to opportunities for enjoyment of the park, or
  • identified as a goal in the park’s General Management Plan or other relevant National Park Service planning documents.

Park resources and values that are subject to no impairment include the park’s scenic, natural, and historic objects, wildlife, and the processes and conditions that sustain them (NPS Management Policies). Therefore, a determination on impairment is made in “Conclusion” of the biotic communities, threatened and endangered species, soil and geology, cultural resource sections, air quality, and noise and soundscapes. Impairment statements are not included for visitor use, traffic, and highway safety, or park operations.


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