When the state board of land commissioners shall ascertain that sections 16 and 36 or any part or parts thereof, granted to the state are or have been lawfully included and embraced within any forest or other reservation established under or by authority of any act of congress, then the said board shall, by and with the approval of the secretary of the interior, or the secretary of agriculture when necessary, select from the surveyed, unreserved and unappropriated public lands of the United States, within the limits of the state of Idaho, other lands equivalent thereto in area and value in legal subdivisions and as contiguous as may be to the section in lieu of which the same is taken: provided, that if the board shall upon examination or otherwise determine that any lands owned by the state in such forest or other reservation borders on or in the vicinity of any lake, waterfall, spring or other naturally advantageous site, or any natural curiosity, or that for any other cause said lands are, or, in the future, may have particular value to the state, then the board shall not certify such lands to the secretary of the interior as a basis for indemnity selections in lieu thereof but the state of Idaho shall retain its title to said lands.