33 U.S.C. § 2280 — Maximum cost of projects

(a) Each total cost stated for an authorized water-resources development or conservation project, including a project authorized in or amended by this Act, a later law, or the Water Resources Development Act of 1988, is the project’s maximum cost. (1) The Secretary may increase that maximum for modifications that do not materially change the project’s authorized scope or functions, but the increase may not exceed 20 percent of the total cost stated for the project in this Act, a later law, or an amendment made by this Act or a later law. (2) The maximum cost must be automatically increased for—(A) changes in construction costs applied to unconstructed features, including real-property acquisitions, preconstruction studies, planning, engineering, and design. The changes are measured from the date this Act or the later law was enacted, unless that Act or law specifies otherwise, using engineering and other appropriate cost indexes; and (B) additional studies, modifications, and actions, including mitigation and other environmental actions, that this Act or a later law authorizes or that changes in Federal law requires.

(b) Despite subsection (a), and consistent with section 701h of this title, the Secretary may accept funds from a non-Federal interest for an authorized water-resources development project that has exceeded its maximum cost under subsection (a), and may use those funds to carry out the project, if doing so does not increase the Federal share of the project’s cost.