. . . . . . . . . . "ses set forth in sub-section (a) above of this section and for the purpose of maintaining and repairing said groins, jetties, banks, dikes, dunes, bulkheads, seawalls, breakwaters, other facilities and other improvements or structures authorized in sub-section (a) of this section; and the Issuing Officers shall sell, execute and deliver bonds in conformity with the provisions of this Act to an amo" . .