Quick search by citation:

16 U.S. Code § 460xx–4 - Land acquisition

The Secretary may acquire lands or interests in lands within the boundaries of the conservation area by exchange, purchase, or donation, except that any lands or interests therein owned by the State or local government may be acquired by donation or exchange only. Any purchase or exchange of lands to be added to the conservation area shall require the consent of the owner of those lands or rights.

Statutory Notes and Related Subsidiaries
Land Exchange and Conservation in Arizona

For provisions relating to land exchange and conservation in southeastern Arizona, see section 539p of this title.