Home The LA CII Stormwater Permit Has Been Adopted: Four Early Milestones for Facility Planning

The LA CII Stormwater Permit Has Been Adopted: Four Early Milestones for Facility Planning

The Los Angeles Regional Water Quality Control Board adopted Order No. R4-2026-0226, General NPDES Permit No. CAS004005, on July 23, 2026. The new Commercial, Industrial, and Institutional Stormwater General Permit becomes effective on October 31, 2026.

The permit establishes requirements for certain privately owned commercial, industrial, and institutional sites within specified portions of the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed and the Los Cerritos Channel/Alamitos Bay Watershed. Applicability depends on multiple site-specific factors and should be evaluated carefully.

Key Milestones

1. Permit Adoption

July 23, 2026

The permit has been formally adopted. Potentially affected owners and operators should begin reviewing the permit’s geographic, ownership, land-use, acreage, impervious-area, drainage, and existing permit-coverage criteria.

2. Permit Effective Date

October 31, 2026

The effective date begins the phased implementation schedule. It should not be confused with the enrollment deadline for an existing discharger.

3. Applicability and Compliance Planning

Begin now

A facility’s evaluation may need to consider:

The adopted permit addresses certain sites already associated with other National Pollutant Discharge Elimination System (NPDES) stormwater coverage. Accordingly, existing IGP coverage should not be assumed to resolve CII Permit applicability without a site-specific evaluation.

4. Notice of Intent (NOI) and Stormwater Pollution Prevention Plan (SWPPP) for Existing Dischargers

October 31, 2027

Existing dischargers seeking coverage must submit a complete Notice of Intent and site-specific Stormwater Pollution Prevention Plan within 12 months after the permit’s effective date.

The permit also establishes later phased submittals for existing dischargers:

These dates correspond to the permit’s requirements of 18 months and 3.5 years after the October 31, 2026 effective date.

New dischargers are subject to a different schedule. The permit requires specified enrollment materials at least 45 days before commencement of the authorized discharge.

Recommended Near-Term Actions

Potentially affected facilities should consider beginning the following activities:

  1. Conduct a documented applicability screening.
  2. Confirm parcel, ownership, operational-control, and land-use information.
  3. Evaluate total and impervious site acreage.
  4. Review existing NPDES permit boundaries and documentation.
  5. Verify drainage areas and discharge locations.
  6. Identify responsible facility and compliance personnel.
  7. Develop a preliminary schedule for the NOI, SWPPP, sampling, and compliance-option evaluation.

Looking Ahead

The phased schedule provides facilities with implementation time, but some decisions may require field verification, drainage evaluation, sampling preparation, engineering analysis, internal budgeting, or coordination with other parties.

Early planning can help facility owners and operators identify data gaps, evaluate compliance risks, and avoid compressed decision-making near future submittal dates.

Michael Baker International assists facility owners and operators with CII Permit applicability evaluations, stormwater engineering, SWPPP development, BMP assessment, monitoring strategy, and NPDES compliance planning.

This article provides a general summary of selected provisions of Order No. R4-2026-0226. It does not constitute a legal opinion or a facility-specific determination. Permit applicability and compliance requirements should be confirmed using current agency materials and site-specific information.