All licensing and regulatory actions subject to this subpart require an environmental assessment except those identified in Sec. 51.20(b) as requiring an environmental impact statement, those identified in Sec. 51.22(c) as categorical exclusions, and those identified in Sec. 51.22(d) as other actions not requiring environmental review. As provided in Sec. 51.22(b), the Commission may, in special circumstances, prepare an environmental assessment on an action covered by a categorical exclusion. [54 FR 27870, July 3, 1989]