Any municipality located on a navigable stream and any parish bounded by or through which a navigable stream runs, or both such municipality and parish in conjunction may, when the necessary authority has been obtained from congress, build bridges across the navigable streams and borrow the money to pay therefor.  The loan shall be evidenced by certificates of indebtedness, bearing not more than five per cent per year interest, running for a period of not more than fifteen years, secured and payable as provided in R.S. 48:913.