Before the county enters into any contract or agreement with the United States and before any plan relating to a flood control or navigation project or the maintenance or operation of a flood control or navigation project is approved, the county shall submit for consideration each contract, agreement, or plan affecting a State road or land in a park or parkway under the jurisdiction of the Commission to: the State Highway Administration; and the Commission. The county may not approve a plan or enter into a contract or an agreement that is inconsistent with: the purposes of the Capper–Cramton Act, Public Law 71–284, 46 Stat. 482; or any agreement between the Commission and the National Capital Planning Commission related to the park and parkway system authorized by that Act.