(a) For efficiency and consistent with § 1507.3(c)(8)(ii) of this subchapter or paragraph (c), agencies shall establish categorical exclusions for categories of actions that normally do not have a significant effect on the human environment, individually or in the aggregate, and therefore do not require preparation of an environmental assessment or environmental impact statement unless extraordinary circumstances exist that make application of the categorical exclusion inappropriate, consistent with paragraph (b) of this section. Agencies may establish categorical exclusions individually or jointly with other agencies.

(b) If an agency determines that a categorical exclusion identified in its agency NEPA procedures covers a proposed action, the agency shall evaluate the action for extraordinary circumstances in which a normally excluded action may have a significant effect.

(1) If an extraordinary circumstance exists, the agency nevertheless may apply the categorical exclusion if the agency conducts an analysis and determines that the proposed action does not in fact have the potential to result in significant effects notwithstanding the extraordinary circumstance, or the agency modifies the action to avoid the potential to result in significant effects. In these cases, the agency shall document such determination and should publish it on the agency's website or otherwise make it publicly available.

(2) If the agency cannot categorically exclude the proposed action, the agency shall prepare an environmental assessment or environmental impact statement, as appropriate.

(c) In addition to the process for establishing categorical exclusions under § 1507.3(c)(8) of this subchapter, agencies may establish categorical exclusions through a land use plan, a decision document supported by a programmatic environmental impact statement or programmatic environmental assessment, or other equivalent planning or programmatic decision for which an environmental document has been prepared, so long as the agency:

(1) Provides the Council an opportunity to review and comment prior to public comment;

(2) Provides notification and an opportunity for public comment;

(3) Substantiates its determination that the category of actions normally does not have significant effects, individually or in the aggregate;

(4) Identifies extraordinary circumstances;

(5) Establishes a process for determining that a categorical exclusion applies to a specific action or actions in the absence of extraordinary circumstances, or, where extraordinary circumstances are present, for determining the agency may apply the categorical exclusion consistent with (b)(1) of this section; and

(6) Publishes a list of all categorical exclusions established through these mechanisms on its website.

(d) Categorical exclusions established consistent with paragraph (c) of this section or § 1507.3(c)(8) of this subchapter may:

(1) Cover specific geographic areas or areas that share common characteristics, e.g., habitat type;

(2) Have a limited duration;

(3) Include mitigation measures that, in the absence of extraordinary circumstances, will ensure that any environmental effects are not significant, so long as a process is established for monitoring and enforcing any required mitigation measures, including through the suspension or revocation of the relevant agency action; or

(4) Provide criteria that would cause the categorical exclusion to expire because the agency's determination that the category of action does not have significant effects, individually or in the aggregate, is no longer applicable, including, as appropriate, because:

(i) The number of individual actions covered by the categorical exclusion exceeds a specific threshold;

(ii) Individual actions covered by the categorical exclusion are too close to one another in proximity or time; or

(iii) Environmental conditions or information upon which the agency's determination was based have changed.

(e) An agency may adopt and apply a categorical exclusion listed in another agency's NEPA procedures to a proposed action or a category of proposed actions consistent with this paragraph. The agency shall:

(1) Identify the categorical exclusion listed in another agency's NEPA procedures that covers its proposed action or a category of proposed actions;

(2) Consult with the agency that established the categorical exclusion to ensure that the proposed action or category of proposed actions to which the agency intends to apply the categorical exclusion is appropriate;

(3) Provide public notification of the categorical exclusion that the agency is adopting, including a brief description of the proposed action or category of proposed actions to which the agency intends to apply the adopted categorical exclusion, the process the agency will use to evaluate for extraordinary circumstances consistent with paragraph (b) of this section, and a brief description of the agencies' consultation;

(4) In applying the adopted categorical exclusion to a proposed action, evaluate the proposed action for extraordinary circumstances, consistent with paragraph (b) of this section; and

(5) Publish the documentation of the application of the adopted categorical exclusion.