Cal. Pub. Res. Code § 6806

Any permit or lease under this chapter shall reserve to the commission the right to allow, upon such terms as the commission may determine to be just, the joint or several use of such easements or rights of way, including easements in tunnels, upon, through, or in the lands leased or permitted, as may be necessary or appropriate for the working of such lands or of other lands containing the deposits described in this chapter.