D.C. Code § 9-707

The Administrator may enter into agreements with the State of Virginia, or with any political subdivision thereof, for such municipal services as the Administrator shall deem necessary to the proper and efficient government of the airport, and he may, from time to time, agree to modifications in any such agreement; provided, however, that where the charge for any such service is established by the laws of the State of Virginia, the Administrator may not pay for such service an amount in excess of the charge so established. There is hereby authorized to be appropriated such sums as may be necessary for the making of payment for services under any such agreement.