The Department of Natural Resources, as successor to the Department of Public Works and Buildings and the Department of Transportation, is authorized to enter into contracts with any agency of the United States Government as may be necessary for the purpose of reimbursing the United States, in accordance with the Federal Water Supply Act of 1958 as amended, for the construction costs and the annual operation and maintenance costs allocated to water-supply storage in the improvements referred to in Section 1 of this Act; provided, however, that costs shall be limited to the increased cost of the project which the United States Government incurs in providing features of construction, operation and maintenance that result in benefits peculiar to the people of this State as allowed by federal law and regulations. Any rights under such contracts may be assigned to the Rend Lake Conservancy District by the Department, provided that no contract or agreement shall be entered into without the written consent of the Governor.