California Code, Public Utilities Code - PUC § 30634

(a) The district may enter into agreements for the joint use or joint development of any property or rights by the district and any city, public agency, or public utility operating transit facilities or nontransit facilities, or both, or any other person, firm, corporation, association, organization, or other entity, public or private, either, in whole or in part, within or outside the district, for the joint use or development of any property of the district or of the city, public agency, public utility, person, firm, corporation, association, organization, or other entity, public or private, or the establishment of through routes, joint fares, station cost-sharing, connector fees, or land, air, or development rights sales or leasing, transfer of passengers, pooling arrangements, or for any other purpose necessary for, incidental to, or convenient for the full exercise of the powers granted in this part.  As to any service which the district is authorized to perform pursuant to this part, the district may contract for the performance of the service by any city, county, or public utility operating transit facilities, the territory of which is, in whole or in part, within the district.

(b) “Joint development” includes, but is not limited to, agreements with any person, firm, corporation, association, organization, or other entity, public or private, to develop or to engage in the planning, financing, or construction of district facilities or development projects adjacent, or physically or functionally related, to district facilities.

(c) Notwithstanding any other provision of this part, no joint development of nontransit facilities may be accomplished without the prior approval of the legislative body of the local jurisdiction within which the development is to take place.

(d) “Transit facilities,” as used in this section, includes land, buildings, and equipment, or any interest therein, whether or not the operation thereof produces revenue, which have as their primary purpose the operation of a rail transit system or the providing of services to the passengers of a rail transit system.

(e) “Nontransit facilities,” as used in this section, includes any land, buildings, or equipment, or interest therein, which is used primarily for the production of transit revenue not arising from the operation of a rail transit system.