The boards of supervisors of the several counties may grant, transfer and convey, without consideration, any real property or interest therein now owned or hereafter acquired by any county, to the United States to be used for National park purposes.

Any county may exercise the right of eminent domain to acquire any property necessary or convenient for carrying out the provisions of this chapter.

The boards of supervisors of the several counties may do and perform all acts that may be necessary to carry out the provisions of this chapter.