When the owners in freehold of both banks of any river in Nebraska for a distance of five miles or more along the river sign a petition to the commission requesting that such river along their lands and on lands adjacent to the river and within one-half mile thereof be made a game and wild fowl sanctuary, the commission upon receiving the promises in writing of such owners to refrain from all shooting or molesting of game upon such proposed sanctuary and further, to the best of their ability, to prevent others from shooting or molesting game thereon may accept such area as a game and wild fowl sanctuary and cause the same to be plainly posted as such and to be protected from violators. The commission may further expend reasonable sums to feed wild fowl upon such sanctuaries. A sanctuary so established may not, without the consent of the commission, be withdrawn by the owners for a period of five years after it is established, and unless the owners of more than one-half of the river banks on both sides of the river running through any such sanctuary sign a petition for vacating the same and file such petition with the commission during the first half of the fifth year of such sanctuary or thereafter in the first half of the fifth year of any added five-year period, such sanctuary shall continue as such unless terminated for good cause by the commission.