The city council may prescribe, by uniform rule or regulation, the minimum course of its excavations or other operations tending to displace the soil; and shall also have the power to prescribe any and all other rules and regulations, uniform in their operation, necessary for the carrying out of the purposes of this chapter.

A person shall not place or cause to be placed in the channel or bed of any river, stream, wash or arroyo, or upon any property over which the Los Angeles County flood control district has an easement for flood control purposes duly recorded in the office of the county recorder of Los Angeles County, any wires, fence, building or other structure, or any rock, gravel, refuse, rubbish, tin cans or other matter which may impede, retard or change the direction of the flow of water in such river, stream, wash or arroyo, or that will catch or collect debris carried by such water, or that is placed where the natural flow of the stream and flood waters would carry the same downstream to the damage or detriment of either private or public property adjacent to the said river, stream, wash, arroyo or channel.

This section does not supersede or modify the provisions of any other ordinance.

Whenever the city council finds that the excavation or quarrying of any rock, sand, gravel or other material in a particular area would create flood hazard or would be otherwise dangerous to the public safety, then before any person excavates or quarries in any part of such area, such person shall first obtain from the chief engineer of the Los Angeles County flood control district a permit to do so.

The chief engineer of the Los Angeles County flood control district may issue such permit upon the condition that the applicant before commencing any such excavation and at such other times during such excavation as may be necessary shall erect such dikes, barriers or other structures as will afford, in the opinion of the chief engineer of the Los Angeles County flood control district, either the same protection as if no excavation should be made, or protection adequate to prevent the flow of the flood waters out of their natural channels.

The chief engineer of the Los Angeles County flood control district may require the submission of plans and specifications showing the nature of the proposed excavation and dikes, barriers or other structures.

No person may make any excavation within such area except after receiving and in conformity with such a permit.

The issuance of such a permit shall not constitute a representation, guarantee or warranty of any kind or nature by the county of Los Angeles or by the Los Angeles County flood control district, or by any officer or employee of either thereof, of the practicability or safety of any structure or other plan proposed and shall create no liability upon, or a cause of action against such public body, officer or employee for any damage that may result from any excavation made pursuant thereto.