Is LID the same as WQMP?

No. LID is the San Diego-specific requirement. WQMP (Water Quality Management Plan) is used in Orange, LA, Riverside, and San Bernardino Counties. They address the same issue — stormwater treatment — but use different frameworks and different terminology.

Can I just pay a fee instead of building BMPs?

Not for single-family residential. The City of San Diego requires on-site treatment. Commercial projects in some jurisdictions may have in-lieu fee options, but this is rare.

What if my soil won't infiltrate?

Then you use alternative BMPs like biofiltration (treats but doesn't infiltrate) or flow-through planters. The LID report documents why infiltration isn't feasible and shows the approved alternative.

Who maintains the BMPs after construction?

You do, as the property owner. The maintenance plan becomes part of the property records and you're responsible for keeping the BMPs functional.

Can I use the same LID design my neighbor used?

No. LID design is site-specific — it depends on your soil type, drainage areas, and project layout. Every project needs its own engineered LID report.

Home›Resources›What Is a LID Report?

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What Is a LID Report?

Low Impact Development — San Diego's framework for treating stormwater before it leaves your site.

San Diego Wants Your Stormwater Cleaner Before It Hits the Storm Drain

In San Diego County, you can't just route your roof and driveway runoff straight to the street anymore. The San Diego Regional Water Quality Control Board requires that new development and major redevelopment projects treat stormwater on-site using Low Impact Development (LID) principles.

A LID report is the civil engineering document that shows how your project will capture, infiltrate, and treat stormwater before it leaves your property. It's required for most residential and commercial projects in the City of San Diego and unincorporated county areas.

This isn't optional, and it's not something you can defer until later. The building department won't approve your grading plan or drainage design until the LID compliance is documented and the treatment measures are shown on the civil plans.

What's in a LID Report

A complete LID report documents how your project meets the stormwater treatment requirements:

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Drainage Management Areas

Identifies which parts of your site generate runoff and how much impervious area each DMA contains.

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BMP Selection & Sizing

Specifies which stormwater Best Management Practices you'll use — infiltration basins, bioretention, permeable pavement, etc.

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Sizing Calculations

Shows that your BMPs are sized to capture and treat the required stormwater volume based on your site's impervious area.

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Infiltration Testing

Documents soil infiltration rates from field testing to verify your site can support infiltration-based BMPs.

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Maintenance Plan

Describes how the BMPs will be maintained over time to ensure they continue functioning properly.

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Compliance Documentation

Shows that your design meets the City or County LID requirements and references the applicable municipal code sections.

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Why LID Isn't Just About Compliance

LID requirements exist because untreated urban runoff is a major source of pollution in San Diego's bays, beaches, and coastal waters. Roofs, driveways, and hardscape wash sediment, metals, oils, and other pollutants straight into the storm drain system, which flows directly to the ocean with zero treatment.

The Regional Water Board doesn't care if this seems like regulatory overreach. They have Clean Water Act authority and they will enforce it. Projects without approved LID don't get building permits. Projects that get built without LID compliance get red-tagged and stopped.

But here's the thing: good LID design actually improves your site. Properly designed infiltration basins double as landscaped areas. Permeable pavement reduces ponding. Bioretention planters add green space. The key is integrating LID into your site design early, not treating it as an afterthought.

When You Need a LID Report?

Common project types and triggers:

New Single-Family Homes

Required in San Diego if you're creating or replacing more than 500 SF of impervious surface.

ADUs

Required if the ADU plus any other new hardscape exceeds the 500 SF threshold.

Additions & Remodels

Required if you're adding or replacing more than 500 SF of impervious area (roof, driveway, patio).

Commercial Development

Always required. Commercial projects have stricter requirements and must meet Priority Development Project criteria.

Hillside Projects

Required, with special considerations for slope stability and drainage integration with LID features.

Common Questions

What clients typically ask about a lid report?:

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