When the Secretary of Agriculture determines that a tract of National Forest System land in Alaska or in the eleven contiguous Western States is located adjacent to or contiguous to an established community, and that transfer of such land would serve indigenous community objectives that outweigh the public objectives and values which would be served by maintaining such tract in Federal ownership, he may, upon application, set aside and designate as a townsite an area of not to exceed six hundred and forty acres of National Forest System land for any one application. After public notice, and satisfactory showing of need therefor by any county, city, or other local governmental subdivision, the Secretary may offer such area for sale to a governmental subdivision at a price not less than the fair market value thereof: Provided, however, That the Secretary may condition conveyances of townsites upon the enactment, maintenance, and enforcement of a valid ordinance which assures any land so conveyed will be controlled by the governmental subdivision so that use of the area will not interfere with the protection, management, and development of adjacent or contiguous National Forest System lands.