Pub. Resources Code, § 21104

(a) Prior to completing an environmental impact report, the state lead agency shall consult with, and obtain comments from, each responsible agency, trustee agency, any public agency that has jurisdiction by law with respect to the project, and any city or county that borders on a city or county within which the project is located unless otherwise designated annually by agreement between the state lead agency and the city or county, and may consult with any person who has special expertise with respect to any environmental impact involved. In the case of a project described in subdivision (c) of Section 21065, the state lead agency shall, upon the request of the applicant, provide for early consultation to identify the range of actions, alternatives, mitigation measures, and significant effects to be analyzed in depth in the environmental impact report. The state lead agency may consult with persons identified by the applicant who the applicant believes will be concerned with the environmental effects of the project and may consult with members of the public who have made a written request to be consulted on the project. A request by the applicant for early consultation shall be made not later than 30 days after the determination required by Section 21080.1 with respect to the project.

(b) The state lead agency shall consult with, and obtain comments from, the State Air Resources Board in preparing an environmental impact report on a highway or freeway project, as to the air pollution impact of the potential vehicular use of the highway or freeway.

(c) A responsible agency or other public agency shall only make substantive comments regarding those activities involved in a project that are within an area of expertise of the agency or that are required to be carried out or approved by the agency. Those comments shall be supported by specific documentation.