Any loss, damage or expense for which the county or the county board may be liable by reason of having entered into an indemnity agreement or undertaking to protect and defend the federal government against loss or damage resulting from or growing out of such flood control works or other similar projects, may be paid for by said county from any funds on hand received from the sale of the bonds issued under the provisions of sections 23-320.01 to 23-320.07 ; Provided, that said county board may for the purpose of saving and protecting the county from any such loss, damage or expense, apply for and purchase from any insurance or indemnity company authorized to transact business in this state, an insurance or indemnity policy or policies of insurance, and pay the cost of obtaining the same from any funds received from the sale of bonds issued under the provisions of sections 23-320.01 to 23-320.07.