In any county wherein a seawall or road protection structure is maintained under the provisions of this chapter, which has invested surplus funds belonging to a road protection bond and interest sinking fund in the purchase of any notes, certificates of indebtedness, bonds, or other interest bearing obligations issued under the authority of Section 65-33-49, or refunding bonds issued or authorized to be issued in lieu thereof, and such notes, bonds, certificates of indebtedness, or refunding bonds are now held by such county for the use and benefit of such fund, and the board of supervisors of such county finds, by order spread upon its minutes, that the needs of such sinking fund demands it, or that it is to the best interest of the county to reduce such obligations so held to cash, such board of supervisors may authorize to be issued and issue and sell new road protection bonds in the aggregate amount of such notes, bonds, or certificates of indebtedness so held and authorized for the purpose of providing funds with which to take up, redeem, and cancel such obligations now held in such sinking fund. Upon the issuance of such road protection bonds, the said bonds, notes, certificates of indebtedness, and refunding bonds issued under authority of said section shall be cancelled.