C.R.S. § 3-1-109

From and after delivery of such deed of cession, the said site and tract of land, and the erections, structures, buildings, fixtures, goods, chattels, and property at any time thereon or thereto belonging, or in any wise appertaining and belonging to the United States, shall be and remain released and exempt from all tollages, taxes, and assessments of every name and nature, for and during the time the United States shall remain the owner thereof.