40 U.S.C. § 8127

(a) Jurisdiction of Mayor .— The Mayor of the District of Columbia has possession, control, and jurisdiction of the land of the Washington Aqueduct adjacent to the Champlain Avenue pumping station and lying outside of the fence around the pumping station as it— (1) existed on August 31, 1918 ; and (2) was transferred by the Chief of Engineers for playground purposes. (b) Jurisdiction of Secretary of the Army Not Affected .— This section does not affect the superintendence and control of the Secretary of the Army over the Washington Aqueduct and the rights, appurtenances, and fixtures connected with the Aqueduct.