Cal. Sts. & High. Code § 94

(a) The department may make and enter into any contracts in the manner provided by law that are required for performance of its duties, provided that contracts with federally recognized Indian tribes shall be limited to activities related to on-reservation or off-reservation cultural resource management and environmental studies and off-reservation traffic impact mitigation projects on or connecting to the state highway system.

(b) To implement off-reservation traffic impact mitigation contracts with federally recognized Indian tribes, all of the following shall apply: (1) Any contract shall provide for the full reimbursement of expenses and costs incurred by the department in the exercise of its contractual responsibilities. Funds for the project shall be placed in an escrow account prior to project development. The contract shall also provide for a limited waiver of sovereign immunity by that Indian tribe for the state for the purpose of enforcing obligations arising from the contracted activity. (2) The proposed transportation project shall comply with all applicable state and federal environmental impact and review requirements, including, but not limited to, the California Environmental Quality Act (Division 13 (commencing with Section 21000) of the Public Resources Code). (3) The department’s work on the transportation project under the contract shall not jeopardize or adversely affect the completion of other transportation projects included in the adopted State Transportation Improvement Program. (4) The transportation project is included in or consistent with the affected regional transportation plan.