Criteria. In determining whether a proposed action will or will not "significantly affect the quality of the human environment," OPDIVs/STAFFDIVs should evaluate the expected environmental consequences of a proposed action by means of the following steps, utilizing the guidance provided in 40 CFR 1508.27:
Step One -- Identify those things that will happen as a result of the proposed action. An action normally produces a number of consequences. For example, a grant to construct a hospital may terminate human services; will involve destruction and construction; will provide a service. Actions may be connected, cumulative, or similar (see 40 CFR 1508.25(a)).
Step Two -- Identify the "human environments" that the proposed action will affect. In accordance with 40 CFR 1508.27, the significance of an action must be analyzed in several contexts, such as society as a whole (human, national), the affected region, the affected interests, and the locality. The significance of an action will vary with the setting of the proposed action. Environments may include terrestrial, aquatic, subterranean, and aerial environments, such as islands, cities, rivers or parts thereof.
Step Three -- Identify the kinds of effects that the proposed action will cause on these "human environments." A change occurs when a proposed action causes the "human environment" to be different in the future than it would have been, absent the proposed action. These changes involve the introduction of various "resources" (including those often characterized as waste).
Example: A decrease in the amount of soil entering a stream; the introduction of a new chemical compound to natural environments.
In addition to organisms, substances, and compounds, the term "resources" include energy (in various forms), elements, structures, and systems (such as a trash collection service in a city). Present environmental impacts and reasonably foreseeable future environmental impacts must be considered.
In identifying changes caused by the proposed action, OPDIVs/STAFFDIVs should identify the magnitude of the changes likely to be caused within smaller and larger "human environments" affected (e.g., part of a city, the whole city, the metropolitan area).
The impacts resulting from the proposed action may be direct, indirect, or cumulative (see 40 CFR 1508.25(c)).
Step Four -- Identify whether these changes are significant. The following points should be considered in conjunction with 40 CFR 1508.8 (effects), 40 CFR 1508.14 (human environment), and 40 CFR 1508.27 ("significantly") in making a decision concerning significance:
A change in the characterization of an environment is significant (e.g., from terrestrial to aquatic);
The establishment of a species in or removal of a species from an environment may be significant;
The more dependent an environment becomes on external resources, the larger the magnitude of change (and the more likely it is to be significant);
The larger the environment under consideration, the lower the amount of change needed before the change may be significant.
The CEQ regulations in 40 CFR 1508.27 describe a number of factors that should be considered in evaluating severity (intensity) of an impact. OPDIVs/STAFFDIVs should consider the cumulative effect of the proposed action. An action may be individually insignificant but cumulatively significant when the action is related to other actions. Significance exists if it is reasonable to anticipate a cumulatively significant impact on the environment. Significance cannot be avoided by terming an action temporary or by breaking it down into small component parts.
Step Five -- Consider alternatives to the proposed action. Alternatives to the proposed action include: