D.C. Code § 16-1382: Retention, for public use, of excess property.

When the authorities of the United States having jurisdiction of real property (or rights or easements) acquired pursuant to this subchapter, elect to retain any of them for the use of the United States, they may use the property (or rights or easements) for park, playground, highway, or alley purposes, or for any other lawful purposes that they deem advantageous or in the public interest.