The deed of conveyance of any surplus real property transferred for public park and recreation purposes under 40 U.S.C. 550(e) must require that the property be used and maintained for the purpose for which it was conveyed in perpetuity. In the event that the property ceases to be used or maintained for that purpose, all or any portion of such property will in its existing condition, at the option of the United States, revert to the United States. The deed of conveyance may contain additional terms, reservations, restrictions, and conditions determined by the Secretary of the Interior to be necessary to safeguard the interests of the United States.