D.C. Mun. Regs. tit. 11, § 2005
2005.1 Discontinuance for any reason of a nonconforming use of a structure or of land, except where governmental action impedes access to the premises, for a period of more than three (3) years, shall be construed as prima facie evidence of no intention to resume active operation as a nonconforming use. Any subsequent use shall conform to the regulations of the district in which the use is located.
SOURCE: § 7107.1 of the Zoning Regulations, effective May 12, 1958; as amended by Final Rulemaking published at 30 DCR 3922, 3928 (August 5, 1983).