Tex. Loc. Gov't Code § 263.204

If a county owns and controls land, or an interest in land, near a federally owned or operated military installation or facility, the county judge of the county, on order of the commissioners court or on a request of the United States that is supported by an order of the commissioners court, may convey to the United States an easement, or other interest in the land, that is necessary for the construction, operation, and maintenance of the installation or facility.