The board of directors of any such district is hereby authorized and directed to apply for and accept and receive gifts, or grants, or loans of money or credits, in whole or in part for the carrying out of any project or projects or improvement or improvements undertaken under this act, from the government of the United States, or any agency thereof: Provided, That money secured through such gifts or grants or loans shall be used exclusively for the payments of labor in connection with the works and improvements hereby authorized. Power and authority is hereby granted to the board of directors of any such drainage district to comply with all conditions and restrictions imposed by any lender or donor of funds, and do all things necessarily incident and proper to meet such requirements and conditions.