((a)) ** In general** In order to insure against cost overruns, each total cost set forth with respect to a project for water resources development and conservation and related purposes authorized to be carried out by the Secretary in this Act or in a law enacted after the date of the enactment of this Act, including the Water Resources Development Act of 1988, or in an amendment made by this Act or any later law with respect to such a project shall be the maximum cost of that project, except that such maximum amount—

((1)) may be increased by the Secretary for modifications which do not materially alter the scope or functions of the project as authorized, but not by more than 20 percent of the total cost stated for the project in this Act, in any later law, or in an amendment made by this Act or any later law; and

((2)) shall be automatically increased for—

((A)) changes in construction costs applied to unconstructed features (including real property acquisitions, preconstruction studies, planning, engineering, and design) from the date of enactment of this Act or any later law (unless otherwise specified) as indicated by engineering and other appropriate cost indexes; and

((B)) additional studies, modifications, and actions (including mitigation and other environmental actions) authorized by this Act or any later law or required by changes in Federal law.

((b)) ** Contributions by non-Federal interests** Notwithstanding subsection (a), in accordance with , the Secretary may accept funds from a non-Federal interest for any authorized water resources development project that has exceeded its maximum cost under subsection (a), and use such funds to carry out such project, if the use of such funds does not increase the Federal share of the cost of such project.section 701h of this title