Cal. Pub. Res. Code § 5074.5

The location of a route or complementary facility of the system across lands under the jurisdiction of a federal agency shall be by contractual agreement between the director and the appropriate federal agency. The director may enter into such agreements, and, subject to the provisions of Section 5075, may expend funds in order to participate with federal agencies in the development and operation of state trail routes across federal lands. The director may exercise similar authority with respect to segments of the system which cross other public lands.