Los Angeles, CA Environmental Rules: Flood Elevation Requirements (2026)

1, effective March 11, 2020 under Ordinance No. 186,503. The rule applies whenever a building site's design flood elevation has not already been specified for the project. In that situation, the Superintendent of Building is authorized to require the applicant to satisfy one of two paths. The first is administrative: obtain and reasonably use flood-elevation data already available from a federal, state, or other qualified source rather than generating new data from scratch. The second is technical: have the elevation independently determined in accordance with accepted hydrologic and hydraulic engineering practices, the same methods used to define special flood hazard areas under federal mapping standards.

Critically, that technical determination cannot be made by just any engineer or the applicant's own staff, the code requires it be undertaken by a registered civil engineer, who must document that the methods used reflect currently accepted engineering practice. The engineer's studies, analyses, and computations must be submitted to the Los Angeles Department of Building and Safety in sufficient detail to allow thorough review and approval before the building official signs off. 3 that applies under the commercial building provisions of Chapter 16.