New Stormwater Permit to Impact The Los Angeles And Los Alamitos Area

The Los Angeles Regional Water Board (LA Water Board) has issued a revised draft General National Pollutant Discharge Elimination System (NPDES) permit (Permit) that will cover stormwater discharges from certain privately owned commercial, industrial, and institutional (CII) sites within two Los Angeles County watersheds: the Dominguez Channel/Greater Los Angeles and Long Beach Harbor Watershed and the Los Cerritos/Alamitos Bay Watershed. This draft Permit has been issued in response to petitions, a 2018 District Court Order, and the United States Environmental Protection Agency (U.S. EPA) using it’s residual designation authority under the Clean Water Act. U.S. EPA has reported that the two watersheds require a reduction in copper and zinc pollutants to restore water quality.

Who Will be Impacted?

Coverage from this Permit will be mandatory for the following CII sites in these watersheds that have five or more acres of total area:

1. Sites not covered by other NPDES permits with five or more acres of impervious surface.
2. Sites entirely or partially covered by other NPDES permits.
3. Sites covered by a No Exposure Certification.
4. Sites covered by a Notice of Non-Applicability.

Sites with an individual NPDES permit are not required to obtain coverage under the Permit unless the individual NPDES permit does not have equally stringent requirements.

Compliance Options

Stormwater dischargers will be required to submit Compliance Option Documents with their Notice of Intent (NOI), a Stormwater Pollution Prevention Plan (SWPPP), and laboratory analytical results.

There will be three compliance options available:

1. Agreement with local watershed management group to fund regional project(s).
2. Facility-specific design standards to reduce stormwater runoff.
3. Direct demonstration of compliance with effluent limitations.

Option 1 is an off-site compliance option where funding is sent to an approved downstream regional project in a Watershed Management Program (WMP). To meet the requirements of this option, a copy of an agreement between the CII site and WMP must be submitted.

Option 2 is an on-site compliance option where structural and/or non-structural controls are implemented for stormwater runoff control. The required documentation to demonstrate compliance includes reports confirming design standards meet with the requirements and reports of installation of the approved controls.

Option 3 is an on-site compliance option where a site-specific Monitoring and Reporting Plan (MRP) is required to meet the requirements. The site-specific MRP includes descriptions of sampling methods and analysis. These reports are required to be submitted within 30 days of the sampling event.

With these three compliance options, submittal of an updated site-specific SWPPP is necessary. With each compliance option, reports will be due annually on December 15.

Existing dischargers and new dischargers will have different requirements for when Permit registration documents are required to be submitted. Existing dischargers will be required to submit an NOI and SWPPP within one year and Compliance Option Documents within three years of the effective date. New dischargers will be required to submit an NOI, SWPPP, and Compliance Option Documents at least 45 days before an authorized discharge occurs.

What’s next?

LA Water Board is currently considering the adoption of the draft Permit. A public hearing to consider the adoption of the draft Permit is scheduled for November 20, 2025.

If this applies to you, now is the time to start strategizing compliance. ALL4 can work with your site to develop an action plan. If you’re not sure if this Permit applies to you, speak to your point of contact at ALL4 or reach out to Meredith Pedraza at mpedraza@all4inc.com or 909.477.7132.