Cal. Sts. & High. Code § 25300

If the Federal Government desires to include any highway improved or to be improved by a district in any scheme of National defense and to use or assume the use of the highway for military or other purposes, the board of directors of the district, either directly or through the proper board or officers of the State, may enter into negotiations respecting the highway and may enter into such contracts or agreements in relation thereto as are mutually satisfactory.