Colo. Rev. Stat. § 3-1-125
Exclusive jurisdiction, for all purposes except such as are in sections 3-1-125 to 3-1-127 expressly reserved over all that tract, piece or parcel of land, situated near Grand Junction, in the county of Mesa, in the state of Colorado, known and described as follows: Commencing at the southeast corner of the southwest quarter section eighteen, township one, south of range one, east of the Ute meridian; thence running east along the south line of said section eighteen, seventy rods; thence north eighty rods, more or less, to the north line of the southwest quarter of the southeast quarter of said section eighteen; thence west seventy rods, to the east line of the southwest quarter of said section eighteen; thence south eighty rods, more or less, to the place of beginning; being the west thirty-five acres of south half of the southeast quarter of section eighteen, township one, south of range one, east of the Ute meridian, and adjoining the lands of the United States used for an Indian school, and as an addition thereto, for like use, be and hereby is ceded, granted, transferred, conferred, and confirmed unto the United States of America, from and after the time when the United States shall become the owner of said tract, for and during the time the United States shall remain the owner thereof; but, nevertheless, jurisdiction to serve the civil process of state, county, and municipal courts and tribunals, within said tract, and also to serve and execute thereon process in criminal cases, by state, county, and municipal officials, in respect of offenses, misdemeanors, crimes, and felonies, committed outside of said tract, is reserved to the state of Colorado.
C.R.S. § 3-1-125