In order to preserve the structural safety of Bureau of Reclamation dams and related facilities the Secretary of the Interior is authorized to perform such modifications as he determines to be reasonably required. Said performance of work shall be in accordance with the Federal reclamation laws (Act of June 17, 1902, 32 Stat. 388, and Acts amendatory or supplementary thereto).

Except as provided in section 509b of this title, construction authorized by this subchapter shall be for the purposes of dam safety and not for the specific purposes of providing additional conservation storage capacity or of developing benefits over and above those provided by the original dams and reservoirs. Nothing in this subchapter shall be construed to reduce the amount of project costs allocated to reimbursable purposes heretofore authorized.

There are hereby authorized to be appropriated for fiscal year 1979 and ensuing fiscal years such sums as may be necessary and, effective October 1, 1983, not to exceed an additional $650,000,000 (October 1, 1983, price levels), and, effective October 1, 2000, not to exceed an additional $95,000,000 (October 1, 2000, price levels), and, effective October 1, 2001, not to exceed an additional $32,000,000 (October 1, 2001, price levels), and, effective October 1, 2003, not to exceed an additional $540,000,000 (October 1, 2003, price levels), and effective October 1, 2015, not to exceed an additional $1,100,000,000 (October 1, 2003, price levels), plus or minus such amounts, if any, as may be justified by reason of ordinary fluctuations in construction costs as indicated by engineering cost indexes applicable to the types of construction involved herein, to carry out the provisions of this subchapter to remain available until expended if so provided by the appropriations Act: Provided, That no funds exceeding $20,000,000 (October 1, 2003, price levels), as adjusted to reflect any ordinary fluctuations in construction costs indicated by applicable engineering cost indexes, shall be obligated for carrying out actual construction to modify an existing dam under authority of this subchapter prior to 30 calendar days from the date that the Secretary has transmitted a report on such existing dam to the Committee on Natural Resources of the House of Representatives and the Committee on Energy and Natural Resources of the Senate. The report required to be submitted by this section will consist of a finding by the Secretary of the Interior to the effect that modifications are required to be made to insure the safety of an existing dam. Such finding shall be accompanied by a technical report containing information on the need for structural modification, the corrective action deemed to be required, alternative solutions to structural modification that were considered, the estimated cost of needed modifications, and environmental impacts if any resulting from the implementation of the recommended plan of modification. For modification expenditures between $1,800,000 and $20,000,000 (October 1, 2015, price levels), the Secretary of the Interior shall, at least 30 days before the date on which the funds are expended, submit written notice of the expenditures to the Committee on Natural Resources of the House of Representatives and Committee on Energy and Natural Resources of the Senate that provides a summary of the project, the cost of the project, and any alternatives that were considered.

Notwithstanding section 507 of this title, if the Secretary, in her judgment, determines that additional project benefits, including but not limited to additional conservation storage capacity, are necessary and in the interests of the United States and the project and are feasible and not inconsistent with the purposes of this subchapter, the Secretary is authorized to develop additional project benefits through the construction of new or supplementary works on a project in conjunction with the Secretary’s activities under section 506 of this title and subject to the conditions described in the feasibility study, provided a cost share agreement related to the additional project benefits is reached among non-Federal and Federal funding participants and the costs associated with developing the additional project benefits are allocated exclusively among beneficiaries of the additional project benefits and repaid consistent with all provisions of Federal Reclamation law (the Act of June 17, 1902, 43 U.S.C. 371 et seq.) and acts supplemental to and amendatory of that Act.