A district may accept, without limitation by any other provisions of this division requiring approval of indebtedness, contributions or loans from the United States, or any department, instrumentality, or agency thereof, for the purpose of financing the construction, maintenance, and operation of any enterprise in which the district is authorized to engage, and may enter into contracts and co-operate with, and accept co-operation from, the United States, or any department, instrumentality, or agency thereof, in the construction, maintenance, and operation, and in financing the construction, maintenance, and operation, of any such enterprise in accordance with any legislation which Congress may have heretofore adopted or may hereafter adopt, under which aid, assistance, and co-operation may be furnished by the United States in the construction, maintenance, and operation or in financing the construction, maintenance, and operation of any such enterprise. A district may do any and all things necessary in order to avail itself of such aid, assistance, and co-operation under any federal legislation now or hereafter enacted. Any evidence of indebtedness issued under this section shall constitute a negotiable instrument.