(a) Designation of lands as administrative site, visitor center, and related facilities; election by owners of term of rights retained; adjustment of compensation
With the exception of not more than eighty acres of land to be designated within the lakeshore boundaries by the Secretary as an administrative site, visitor center, and related facilities, as soon as practicable, any owner or owners of improved property on the date of its acquisition by the Secretary may, as a condition of such acquisition, retain for themselves and their successors or assigns a right of use and occupancy of the improved property for noncommercial residential purposes for a definite term not to exceed twenty-five years, or, in lieu thereof, for a term ending at the death of the owner, or the death of his spouse, whichever is the later. The owner shall elect the term to be reserved. The Secretary shall pay to the owner the fair market value of the property on the date of such acquisition less the fair market value on such date of the right retained by the owner.

(b) Termination right of Secretary upon determination that retained property or any portion thereof has ceased to be used for noncommercial residential or agricultural purposes; adjustment of compensation
A right of use and occupancy retained pursuant to this section may be terminated with respect to the entire property by the Secretary upon his determination that the property or any portion thereof has ceased to be used for noncommercial residential or for agricultural purposes, and upon tender to the holder of a right an amount equal to the fair market value, as of the date of the tender, of that portion of the right which remains unexpired on the date of termination.

(c) "Improved property" defined
The term "improved property", as used in this section, shall mean a detached, noncommercial residential dwelling, the construction of which was begun before January 1, 1967, or before January 1, 1985 for those lands referred to in section 460w(b) of this title (hereinafter referred to as "dwelling"), together with so much of the land on which the dwelling is situated, the said land being in the same ownership as the dwelling, as the Secretary shall designate to be reasonably necessary for the enjoyment of the dwelling for the sole purpose of noncommercial residential use, together with any structures accessory to the dwelling which are situated on the land so designated.