d dos In some instances environmental costs may outweigh economic and technical benefits and in other instances they may not. But NEPA mandates a rather finely tuned and “systenatic" balancing Sow analysis in each instance. To insure that the balancing analysis is carried out and given full effect, Section 102(2)(C) requires that. responsible officials of all agencies prepare a . “detailed statement" covering the impact . of particular actions on the environment, the environmental costs which might be avoided, and alternative measures which might alter the cost benefit equation. ~ 2 ERC at_1781-82. renner a aes = = — - — -.5- - = os - ~ = - "Similarly, in*ydtural Resources ‘Desfensest Council Veo >,2Moxton, the’ Gourk- observed|that ee ee ee The impact statement provides a basis for (a) evaluation of the benefits of the proposed project in light of its environmental risks, and (b) comparison of the net balance for the proposed project with the environmental risk presented by alter- native courses of action. 3 ERC at 1561. - ° = These judicial comments do not, however, detract from the primary purpose of the 102 statement: the assessment of the environmental effects of possible actions. NEPA was enacted out of a concern that environmental considerations were not being fully canvassed before action, and the purpose of Sec-~ tion 102(2}(C) is primarily to require a "detailed statement" of environmental effects. Where an. agency's proposal entails adverse environmental ot fo. cr] i? consequences, the 102 statement must identify the countervailing interests that would support a