No such moneys shall be appropriated, borrowed, or advanced to the Commonwealth by any such municipality except for expenditure on a project or improvement which has been prior to the passage of this act authorized by law to be constructed and completed by the Commonwealth or any department, board or commission thereof for the conservation of water and the control of floods. Such moneys, when appropriated or borrowed, shall be paid over to the Secretary of Forests and Waters¹ of the Commonwealth, who shall immediately pay the same over to the State Treasurer for safe-keeping. Such moneys so paid over to the State Treasurer shall be placed in a separate fund and shall be expended by the Department of Forests and Waters² for the construction and completion of any project or improvement for the conservation of water and the control of floods authorized by law and designated by the municipality which has paid over said money, and for such purposes said moneys in said special fund from time to time are hereby appropriated. Payments from said fund shall be made by warrant of the Auditor General on the State Treasurer after requisition by the Secretary of Forests and Waters.