Veh. Code, § 31304

(a) The transportation of hazardous materials and hazardous waste for which the display of placards or markings is required pursuant to Section 27903 may be restricted or prohibited, by the Department of the California Highway Patrol, after consultation with the Department of Transportation, with regard to state or interstate highways, or by a city or county by ordinance or resolution, after formal notice to the Department of the California Highway Patrol and with the concurrence of their appropriate transportation planning agency defined in Section 29532 of the Government Code, with regard to specified highways under their control, if all of the following requirements are met:

(1) The respective highway is appreciably less safe than a reasonable alternate highway as determined by using either of the following criteria:

(A) The “Guidelines for Applying Criteria to Designate Routes for Transporting Hazardous Materials” prepared by the Federal Highway Administration (FHWA A-IP-80-15).

(B) The Department of the California Highway Patrol or the city or county, whichever has jurisdiction pursuant to subdivision (a), determines that the respective highway is located within the watershed of a drinking water reservoir which meets all of the following requirements:

(i) The reservoir is owned or operated by a public water system, as defined in Section 116275 of the Health and Safety Code.

(ii) The reservoir has a capacity of at least 10,000 acre feet.

(iii) The reservoir directly serves a water treatment plant, as defined in Section 116275 of the Health and Safety Code.

(iv) The reservoir is impounded by a dam, as defined in Section 6002 of the Water Code.

(v) The reservoir’s shoreline is located within 500 feet of the highway.

(2) The restriction or prohibition on the use of the highway pursuant to this section is not precluded or preempted by federal law.

(3) The restriction or prohibition does not eliminate necessary access to local pickup or delivery points consistent with safe vehicle operation; does not eliminate reasonable access to fuel, repairs, rest, or food facilities that are designed and intended to accommodate commercial vehicle parking, when that access is consistent with safe vehicle operation and when the facility is within one-half road mile of points of entry or exit from the state or interstate highway being used; or does not restrict or prohibit the use of highways when no other lawful alternative exists.

(4) Written concurrence has been obtained from affected surrounding jurisdictions, including, but not limited to, state agencies, counties, cities, special districts, or other political subdivisions of the state, that the proposed restriction or prohibition is not incompatible with through transportation. If written concurrence is not granted by one of the affected surrounding jurisdictions, that action may be appealed to the appropriate transportation planning agency for final resolution.

(5) The highway is posted by the agency responsible for highway signs on that highway in conformity with standards of the Department of Transportation.

(6) A list of the routes restricted or prohibited is submitted to the Department of the California Highway Patrol.

(7) The highway is included in a list of highways restricted or prohibited pursuant to this section which is published by the Department of the California Highway Patrol and is available to interested parties for not less than 14 days.

(b) Notwithstanding any prohibition or restriction adopted pursuant to subdivision (a), deviation from restricted or prohibited routes is authorized in an emergency or other special circumstances with the concurrence of a member of the agency having traffic law enforcement authority for the highway.