Information from public and private sources; confidentiality of classified or privileged data
The Secretary may obtain from public sources, or purchase from private sources, any survey, data, report, or other information (including interpretations of such data, survey, report, or other information) which may be necessary to assist him in preparing any environmental impact statement and in making other evaluations required by this subchapter. Data of a classified nature provided to the Secretary under the provisions of this subsection shall remain confidential for such period of time as agreed to by the head of the department or agency from whom the information is requested. The Secretary shall maintain the confidentiality of all privileged or proprietary data or information for such period of time as is provided for in this subchapter, established by regulation, or agreed to by the parties.