RSA 482:20: Termination of Rights.

All rights, powers, privileges and franchises conferred upon any corporation, enabling it to construct and maintain milldams upon the streams of this state and to flow lands or do any other act necessary to the development of hydroelectric energy, shall terminate and be forfeited at the end of 6 years from the date on which the act of incorporation took effect, unless the actual work of constructing such dams or power plants shall be commenced during such 6 years and be prosecuted with reasonable diligence until such dams and plants are completed and in operation.