When the proposed action will have significant adverse effects on the human environment, and there is incomplete or unavailable information, the proponent will ensure that the EIS addresses the issue as follows:
(a) If the incomplete information relevant to reasonably foreseeable significant adverse impacts is essential to a reasoned choice among alternatives and the overall costs of obtaining it are not exorbitant, the Army will include the information in the EIS.
(b) If the information relevant to reasonably foreseeable significant adverse impacts cannot be obtained because the overall costs of obtaining it are exorbitant or the means to obtain it are not known (for example, the means for obtaining it are beyond the state of the art), the proponent will include in the EIS:
(1) A statement that such information is incomplete or unavailable.
(2) A statement of the relevance of the incomplete or unavailable information to evaluating the reasonably foreseeable significant adverse impacts on the human environment.
(3) A summary of existing credible scientific evidence that is relevant to evaluating the reasonably foreseeable significant adverse impacts on the human environment.
(4) An evaluation of such impacts based upon theoretical approaches or research methods generally accepted in the scientific community.