16 U.S.C. § 543b: Acquisition of lands

any lands or interests therein within the boundary of the Scenic Area which are owned by the State of California or any political subdivision thereof (including the city of Los Angeles) may be acquired only by donation or exchange; and lands or interests therein within the boundary of the Scenic Area which are not owned by the State of California or any political subdivision thereof (including the city of Los Angeles) may be acquired only with the consent of the owner thereof unless the Secretary determines, after written notice to the owner and after opportunity for comment, that the property is being developed, or proposed to be developed, in a manner which is detrimental to the integrity of the Scenic Area or which is otherwise incompatible with the purposes of sections 543 to 543h of this title. Not later than six months after September 28, 1984 , the Secretary shall publish specific guidelines under which determinations shall be made under paragraph (2) of subsection (a). No use which existed prior to June 1, 1984 , within the area included in the Scenic Area shall be treated under such guidelines as a detrimental or incompatible use within the meaning of such paragraph (2). reconstruction of an existing building, construction of attached structural additions, not to exceed 100 per centum of the square footage of the original building, and construction of reasonable support development such as roads, parking, water and sewage systems shall be treated as detrimental to the integrity of the Scenic Area or as an incompatible development within the meaning of paragraph (2) of subsection (a). Notwithstanding any other provision of law, the Secretary shall only be required to prepare an environmental assessment of any exchange of mineral or geothermal interest authorized by sections 543 to 543h of this title.