NPS Director's Order 12: Conservation Planning, Environmental Impact Analysis and Decision Making Back to EQD
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White Sands National Monument, NM2.8 Overview of the NEPA Process — Affected Environment

A. Boundary-setting

Once alternatives and issues have been defined, the analysis area boundary should be delineated for each resource. The analysis boundary will be different for each resource. For instance, the impact to soils or vegetation of grading a site for a sewage treatment plant may be confined to the building footprint. The impact to water quality may be the entire length of the river where treated wastewater is discharged and beyond. If another source of impact to the same river exists upstream, this section of river may also be part of the analysis area for water quality.

Sometimes the analysis boundary for a particular resource will change with different alternatives. In the example above, analyzing three or four different locations for a sewage treatment plant means analyzing impacts to vegetation in those locations.

Fully describing affected environment usually requires knowledge about the extent of impacts, and the description may be refined as impact analysis on a particular proposal proceeds.

Ruins, Mesa Verde National Park, COIn NEPA, “affected” environment means just that — resources expected to experience environmental impacts. Therefore, you should not bother with drawing analysis boundaries or collecting data to describe resources that are not likely to be affected by the alternatives.

For those resources that will sustain impacts, collecting accurate and adequate data on their present status (location, nature, condition, scope, size, etc.) is critical in determining impacts, and must be available before helpful NEPA analysis can begin. A geographic information system or other mapping system not only can be the basis of excellent analyses, but can help parks decide how best to develop or manage resources. In other words, quality data will help in making quality decisions. The list of resources in the ESF (appendix 1) is a good beginning point in determining which resources to consider.

Further Links:

Issues, Impact Topics and Data

National Park Service Resources

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