The township trustees and the county surveyor and county clerk shall notify the secretary of state of all lands referred to herein, but the secretary of state shall not cause the survey of any tract of land containing less than five acres, unless in his judgment the value thereof shall be greater than the expense of surveying and selling the same: Provided, That nothing in this act contained shall be so construed as to change the law of accretion as the same is now construed and defined by the supreme court of the United States.