Los Angeles Regional Water Board Adopts New CII Stormwater Permit

On July 23, 2026, the Los Angeles Regional Water Quality Control Board adopted a new Commercial, Industrial, and Institutional (“CII”) Stormwater Permit that could create significant new compliance obligations for certain commercial, industrial, and institutional properties in portions of Los Angeles County. In general, the permit applies to facilities within the Dominguez Channel and Los Cerritos watersheds that have five or more acres of impervious surface or, in some circumstances, five or more acres of total site area, including certain facilities that currently rely on No Exposure Certifications, Notices of Non-Applicability, or other forms of stormwater permit coverage. The permit also contains broad provisions regarding campus-style developments, allowing contiguous parcels and certain parcels separated by public rights-of-way to be aggregated for coverage purposes, and applies to the commercial, industrial, or institutional portions of mixed-use developments.

The permit is expected to become effective on or around October 31, 2026. Covered sites will be required to conduct stormwater sampling, develop a Stormwater Pollution Prevention Plan (“SWPPP”), implement required best management practices, pay annual fees, and comply with one of three available compliance pathways, some of which could involve substantial capital expenditures. Owners and operators of potentially covered facilities should consider promptly evaluating whether any facilities fall within the permit’s geographic scope and whether existing stormwater permit coverage, site configuration, acreage, ownership structure, or mixed-use characteristics necessitate permit coverage.

Notably, similar requests are pending in several other regions of California, including Lower San Diego, Ontario, Salinas, Santa Rosa, the San Francisco Bay Area, and Sacramento, which could lead to similar permit programs being adopted by Regional Water Boards in those additional watersheds. Owners and operators potentially subject to the new CII Stormwater Permit or similar pending permits will want to consider applicability assessments, compliance planning, and implementation strategies.