Does the New Los Angeles CII Stormwater Permit Apply to Your Property?

Stormwater Legal & Compliance Center / Article

The new Los Angeles CII stormwater permit does not apply to every commercial property in Los Angeles County. Coverage depends on the watershed, the type of site, its size under the applicable test, and its existing stormwater permit coverage. A property address and total parcel acreage are useful starting points, but they are not a complete determination.

The Los Angeles Regional Water Quality Control Board adopted Order R4-2026-0226 on July 23, 2026, with a stated effective date of October 31, 2026. The following questions help identify the facts needed to evaluate a property under that order.

Is the site in one of the designated watersheds

For background on water-quality issues in one of these watersheds, read our Dominguez Channel stormwater article. It does not determine whether CII coverage applies to a particular property.

The permit addresses qualifying sites in the Dominguez Channel/Los Angeles and Long Beach Inner Harbor Watershed and the Los Cerritos Channel/Alamitos Bay Watershed. Municipal boundaries and watershed boundaries are not interchangeable.

Review the permit's maps together with the site's actual drainage. Runoff can reach a receiving water through public storm drains or private conveyances; a property does not have to border a channel or bay. A map should be used as part of the review, with technical confirmation where boundaries or drainage pathways are uncertain.

Is it a qualifying privately owned CII site

CII means commercial, industrial, and institutional. The permit excludes solely residential facilities. The analysis should identify the actual facility and its use rather than rely solely on the property's marketing description.

Multiple parcels, shared facilities, and campus arrangements deserve particular attention. Do not assume that separate parcel numbers or tenant leases automatically create separate sites for the permit's purposes. Examine the order's definitions and the factual relationship between the parcels, operations, and drainage.

Which five-acre test applies?

The CII stormwater permit uses different five-acre tests depending on the site’s existing NPDES stormwater permit coverage.

For a site not covered by another NPDES stormwater permit, Section 3.1.2 looks at five or more acres of impervious surface. Impervious surfaces include rooftops, pavement, and other areas that prevent or significantly reduce water from soaking into the ground.

For certain sites already covered by another NPDES stormwater permit, Section 3.1.3 instead looks at five or more acres of total area, along with other requirements for that type of coverage.

The distinction matters. A six-acre property with four acres of impervious surface does not automatically meet the test for an otherwise unpermitted site simply because the property is larger than five acres. At the same time, a business should not use the impervious-surface test where the CII permit calls for total acreage.

The permit language should control the analysis. The size of a parking lot or the total size of a property alone does not determine whether a site needs CII stormwater permit coverage.

What does the existing stormwater permit actually cover?

An existing stormwater permit or filing may not cover the entire facility. The CII permit specifically addresses No Exposure Certifications, Notices of Non-Applicability, and sites that have only partial coverage under another NPDES stormwater permit.

Review the existing filing carefully. Determine what area, activities, and stormwater discharges it actually covers rather than assuming that an old filing covers the entire property.

An individual NPDES permit is also not automatically a substitute for CII coverage. Section 3.1.4 addresses facilities with individual NPDES permits that contain requirements at least as stringent as the CII permit. That requires comparing the actual permit requirements.

Do not terminate existing stormwater permit coverage or assume that the CII permit replaces another permit without first reviewing the applicable requirements and termination procedures. If the interaction between permits is unclear, the issue should be addressed before changing the facility’s existing coverage.

Assemble an applicability file

A useful starting file includes a current site plan, parcel and ownership information, measurements supporting the acreage calculation, drainage information, and all existing permit documents. Include no-exposure or non-applicability filings, relevant leases, and Water Board correspondence.

Record the basis for the conclusion, including assumptions that require verification. An undocumented belief that the property is too small, already permitted, or outside the watershed can be difficult to evaluate later. Revisit the analysis when the property expands, drainage changes, or operations and ownership change.

What to do if coverage appears likely

Identify the responsible discharger and begin evaluating the required submissions and compliance options. Do not wait for a reminder letter to organize the work. The CII deadlines guide explains the staged schedule, and the owner and operator article addresses responsibility.

For a legal review of a particular property, visit our CII permit legal services page or Get A Case Evaluation.

Frequently asked questions

This information is educational and is not a property-specific coverage determination. Confirm current permit status and applicable requirements before acting.

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