In exercising the exchange authority granted by subsection (a) of this section or by section
1715
(a) of this title, the Secretary concerned may accept title to any non-Federal land or interests therein in exchange for such land, or interests therein which he finds proper for transfer out of Federal ownership and which are located in the same State as the non-Federal land or interest to be acquired. For the purposes of this subsection, unsurveyed school sections which, upon survey by the Secretary, would become State lands, shall be considered as “non-Federal lands”. The values of the lands exchanged by the Secretary under this Act and by the Secretary of Agriculture under applicable law relating to lands within the National Forest System either shall be equal, or if they are not equal, the values shall be equalized by the payment of money to the grantor or to the Secretary concerned as the circumstances require so long as payment does not exceed 25 per centum of the total value of the lands or interests transferred out of Federal ownership. The Secretary concerned and the other party or parties involved in the exchange may mutually agree to waive the requirement for the payment of money to equalize values where the Secretary concerned determines that the exchange will be expedited thereby and that the public interest will be better served by such a waiver of cash equalization payments and where the amount to be waived is no more than 3 per centum of the value of the lands being transferred out of Federal ownership or $15,000, whichever is less, except that the Secretary of Agriculture shall not agree to waive any such requirement for payment of money to the United States. The Secretary concerned shall try to reduce the amount of the payment of money to as small an amount as possible.