Whenever fifty percent or more of the area of a city, town, or village organized under the laws of this state is liable to be inundated as a result of the construction of a lake, reservoir or other body of water, and it is determined by the legislative body of the city, town, or village, that it is impracticable to annex adjacent or contiguous territory to afford the necessary additional area for the city, town, or village, the legislative body of the city, town, or village may extend its governmental authority over a new townsite in the manner provided in sections 71.016 to 71.019.