33 U.S.C. § 467n — Recovery of dam modification costs required for safety purposes

(a) After November 17, 1986, when the Secretary modifies a dam or related facility that the Secretary built or runs — and the reason for the change is new flood or earthquake (hydrologic or seismic) data, or new design or construction standards needed for safety — the cost of that modification must be recovered this way: (1) 15 percent of the modification cost is assigned to the project's original purposes, using the same cost split that already applied to the project when the work began. Non-federal partners pay their share of each purpose the same way they did for the original construction. But the Secretary of the Interior collects the share assigned to irrigation using the repayment rules of Public Law 98–404. (2) Repayment under this subsection — except for the irrigation share — can be spread out, with interest, over no more than 30 years from when the work is finished. Here is how the interest rate is set, step by step: the Secretary of the Treasury looks at the average market yields on outstanding U.S. Treasury securities with maturities close to the repayment period, during the month before the fiscal year the costs happen; the Secretary of the Treasury then adds one-eighth of one percentage point for transaction costs; and if more than one rate comes out of that process, the Secretary of the Treasury sets a single rate that is the weighted average of those rates. (b) Nothing in this section changes the Secretary's authority to do work under Public Law 84–99, as amended (33 U.S.C. 701n), or how the costs of that work are shared.