N.H. Rev. Stat. Ann. § 227:4

To the extent that it may be necessary to carry out the provisions of this subdivision the department shall have power to use and control public lands of the state. Forthwith upon the acquisition by the department in the name of the state through purchase, condemnation, or otherwise of any real property or interest or easement therein, such property or rights shall, without further action, and by virtue hereof, be and become dedicated to the uses and purposes of the department.