Newly Adopted Commercial, Industrial, and Institutional Stormwater Permit in Two LA County Watersheds

On July 23, 2026, the Los Angeles Regional Water Quality Control Board (“Water Board”) adopted the Commercial, Industrial, and Institutional (CII) Permit, a regional stormwater permit which expands stormwater regulations to CII facilities located in Los Angeles County that discharge to either the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed or the Los Cerritos Channel/Alamitos Bay Watershed. The CII permit has an effective date of October 31, 2026.

Background

The USEPA administers the Clean Water Act, which includes the National Pollutant Discharge Elimination System (NPDES) program. The NPDES stormwater program regulates stormwater discharges from municipal storm sewer systems, construction activities, industrial activities, and additional discharges on a case-by-case basis, which is referred to as USEPA’s residual designation authority that may be triggered by legal petition. Since the early 1990s, California has regulated industrial facilities under a statewide general stormwater permit (the “Industrial General Permit” or “IGP”) issued under the authority of the federal NPDES program. In recent years, USEPA has received petitions from various non-governmental organizations (NGOs) requesting that USEPA use its residual designation authority to further regulate stormwater discharges beyond the existing IGP.

In 2015, the USEPA received a petition from NGOs requesting that the USEPA use its residual designation authority to regulate stormwater discharges from CII facilities located within the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed and the Los Cerritos Channel/Alamitos Bay Watershed. The petitions stated that privately-owned CII facilities were contributing to metal impairments (specifically copper and zinc) in these two watersheds. USEPA denied this petition on the basis that existing NPDES permits issued by the Water Board were already addressing water quality impairments. However, in 2017, the NGO petitioners appealed this decision and a U.S. District Court ultimately ruled in Los Angeles Waterkeeper v. Pruitt, 320 F. Supp.3d 1115 (C.D. CA 2018) that USEPA’s basis for denying the petition was not allowed under the Clean Water Act. As a result of the court order, the USEPA issued its final designation notice for CII facilities on November 20, 2024 to regulate stormwater discharges from CII facilities within the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed and the Los Cerritos Channel/Alamitos Bay Watershed.

Permit Coverage

After the initial publication of the draft CII Permit in July of 2022, the CII Permit has undergone additional revisions based on public comments. The adopted CII Permit was published on July 31, 2026.

The CII Permit applies to privately owned CII facilities with five or more acres of impervious surfaces, as well as facilities subject to the IGP with five or more total acres. Examples of impervious surfaces regulated under this permit include streets, parking lots, rooftops, sidewalks, patios, storage areas, roads, asphalt, and concrete. In addition to regulating privately-owned commercial and institutional facilities (such as shopping centers, office complexes, warehouses, private schools, car dealerships, etc.), the CII Permit will regulate non-industrial parts of industrial facilities, such as employee parking lots and roof runoff, and non-industrial areas of industrial facilities with No Exposure Certifications under the IGP.

The CII Permit is targeted to reduce various pollutant impairments and will require that stormwater runoff from subject CII facilities meet the total maximum daily load numeric effluent limits (NELs) established for these watersheds. The compliance options under the CII Permit include:

► Compliance Option 1 – Offsite agreement with a local watershed management group to help fund a regional watershed management project;
► Compliance Option 2 – Onsite facility-specific design standard to reduce stormwater runoff; and
► Compliance Option 3 – Direct compliance with NELs through sampling of stormwater runoff.

All Compliance Options will require facilities to develop a site-specific Stormwater Pollution Prevention Plan (SWPPP) and implement minimum Best Management Practices such as good housekeeping and an employee training program.

Changes to the CII Permit

The adopted CII Permit has a few key changes to previous versions of the permit:

1. Prior to selecting a Compliance Option, all CII Facilities must conduct initial sampling and analysis of stormwater discharges and non-stormwater discharges for ammonia, biochemical oxygen demand, indicator bacteria, methylene blue activated substances (MBAS), nitrogen/biostimulatory substances, oil and grease, PAHs, pesticides, pH, temperature, total residual chlorine, total suspended or settleable solids, zinc, and copper. Initial sampling results will be required to be submitted within eighteen months of the effective date of the CII Permit.
2. CII Facilities are required to provide photographic documentation of:
   1. Stormwater visual observations under Compliance Options 1 and 3. Photographic evidence is also required to demonstrate when no discharge occurs from a discharge location during a QSE.
   2. Bypass visual observations under Compliance Option 2.
3. Sample results above three-year average effluent limitations will be considered a single violation rather than a violation for each day of the three-year period.
4. New toxicity monitoring requirements which are triggered based on the toxicity limits in Table 1 of the CII Permit. Requirements include preparation of initial investigation toxicity reduction evaluation (TRE) and toxicity identification evaluation (TIE).
5. Existing Dischargers applying for coverage under the CII Permit must submit Compliance Option Documents within three and a half years of the effective date of the permit. Existing Discharges are still required to submit a Notice of Intent and SWPPP within one year of the permit effective date but have an additional two and a half years to choose their compliance option.

Impacts of The CII Permit

There are numerous potential impacts from the CII Permit on the regulated businesses in Los Angeles County.

Increased Regulatory Burden

The CII Permit expands the state’s authority by regulating stormwater runoff from privately-owned commercial and institutional facilities, many of which do not currently require NPDES permit coverage for stormwater discharges. While the IGP covers most manufacturing operations, the CII Permit will pull in many new permitted facilities such as shopping centers, warehouses, office complexes, and car dealerships, and will require these facilities to manage their stormwater runoff.

For many industrial facilities located in Los Angeles County, the CII Permit will also require monitoring of the non-industrial areas of their facilities. For facilities currently subject to the IGP, employee parking lots and rooftops may be considered exempt, non-industrial pollutant sources. Under the CII Permit, subject facilities will be required to monitor the stormwater runoff from these sources regardless. This new monitoring requirement could lead to large capital expenditures under any of the three Compliance Options.

Economic Impacts

The Water Board updated economic analysis data of each Compliance Option presented during the public hearing is shown in the table below.

Costs from Compliance Option 1 were determined based on discussions with affected Watershed Management Groups.

Costs from Compliance Option 2 were determined based on data from stormwater retrofit BMP projects across the US.

For Compliance Option 3, the wide range of annualized estimated costs reflects costs for facilities that would only be required to sample their stormwater discharges up to facilities that would need to implement additional BMPs, such as stormwater treatment systems, to meet the effluent limitations.

Based on this information, the CII Permit represents a large capital and ongoing investment for facilities to comply under any compliance option.

Next Steps

The Water Board plans to conduct outreach to potential CII facilities, but it is ultimately your responsibility to determine whether your facility is subject to the adopted CII Permit. If your facility is subject to the CII Permit, the Notice of Intent and SWPPP are due by October 31, 2027 for any Existing Discharger.

Evaluating the Compliance Options under the CII Permit is critical to determine how best to comply with this new permit. Being proactive with engaging Watershed Management Groups, designing on-site capture systems, or determining if your facility can meet effluent limitations will decrease compliance and enforcement risks under the new CII Permit.

If you would like to discuss your compliance options under the CII Permit and how it may impact your facility, please contact Colleen Grainger or Sydney Kwan of Trinity’s Irvine office or call 949.567.9880.