Pub. Util. Code, § 29081

The district may cooperate with and enter into agreements with the State of California or any public agency for the acquisition, construction, completion, maintenance, operation, or repair, joint or otherwise, and in whole or in part, of transit facilities. In connection with any such cooperation or contract, the State or any public agency may make public contributions to the district as in the judgment of the Legislature, or the governing board of the agency, are necessary or proper for its undertaking, and the district may reimburse the State or public agency for any such advance or contribution from the proceeds of the sale of bonds or any other funds available to the district, except that any agreement requiring reimbursement of contributions or advances by obligating the district to incur an indebtedness will be subject to the procedures and limitations provided in Chapter 8 of this part. The State or any public agency may also authorize, aid and assist the district to carry out any activity which the State or public agency is by law authorized to perform and carry out on its own behalf.