40 U.S.C. § 8121 — Improper appropriation of streets

prevent the improper appropriation or occupation of any public street, avenue, square, or reservation in the District of Columbia that belongs to the Federal Government;

reclaim the street, avenue, square, or reservation if unlawfully appropriated;

prevent the erection of any permanent building on property reserved to or for the use of the Government, unless plainly authorized by law; and

report to Congress at the beginning of each session on the Secretary’s proceedings in the premises, together with a full statement of all property described in this subsection, and how, and by what authority, the property is occupied or claimed.