$272,000,000 is authorized to be appropriated for the carrying out of the modified adopted project, and all unexpended balances of appropriations heretofore made for the prosecution of said flood-control project are made available for the purposes of sections 642a, 702a–1, 702a–2 to 702a–12, 702g–1, 702j–1, 702j–2, 702k–1, and 702k–2 of this title.