Except as provided in paragraph (2), the Secretary is authorized to acquire lands or interests therein within the park only by donation.

If the Secretary determines that lands within the protection zone are being used, or there is an imminent threat that such lands will be used, for a purpose that is incompatible with the purposes of this subchapter, the Secretary may acquire such lands or interests therein by means other than donation.

The Secretary may acquire lands within the historic zone subject to terms and easements providing for the management and commercial operation of existing hiking and cross-country ski trails by the grantor, and the grantor’s successors and assigns, such terms and easements shall be in a manner consistent with the purposes of the historic zone. Any changes in the operation and management of existing trails shall be subject to approval by the Secretary.

The primary purpose of the protection zone shall be to preserve the general character of the setting across from the Marsh-Billings-Rockefeller Mansion in such a manner and by such means as will continue to permit current and future compatible uses.

The Secretary shall pursue protection and preservation alternatives for the protection zone by working with affected State and local governments and affected landowners to develop and implement land use practices consistent with this subchapter.