16 U.S.C. § 445d
The Secretary of the Interior is authorized to add to the Pipestone National Monument such part of the Pipestone school reserve, not exceeding two hundred and fifty acres, as he deems necessary to protect archeological remains, to acquire by purchase or condemnation not exceeding ten acres of non-Federal land, as he deems necessary to improve the boundary and administration of the Pipestone National Monument Federal land, and to redefine the exterior boundaries of the Pipestone National Monument to include the lands so transferred and acquired pursuant to this section. All lands added to the Pipestone National Monument pursuant to this section shall be subject to the provisions of subsections (b) and (c) of section 445c of this title.
16 U.S.C. § 445d