Is WQMP the same as LID?

Functionally, yes — both address stormwater treatment requirements. LID is the San Diego term. WQMP is used in Orange and LA Counties. The concepts and BMPs are nearly identical.

What's a Priority Development Project?

It's any project that falls into categories defined by the Regional Board — single-family hillside homes, multi-family (10+ units), commercial, restaurants, parking lots, etc. If your project is a PDP, you need a WQMP.

Can I use a proprietary device instead of landscaped BMPs?

Sometimes. Proprietary devices (like stormwater filters or vaults) can be used, but they must be approved by the jurisdiction and properly sized. Many jurisdictions prefer LID-style landscaped BMPs where feasible.

Who's responsible for long-term maintenance?

The property owner. The WQMP maintenance plan becomes a recorded document and you're legally responsible for keeping the BMPs functional in perpetuity.

What happens if I don't maintain the BMPs?

The city can inspect and cite you for non-compliance. In extreme cases, they can perform the maintenance themselves and bill you for it, plus penalties.

Home›Resources›What Is a WQMP?

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What Is a WQMP?

Water Quality Management Plan — the stormwater compliance document required across OC and LA County.

Orange County and LA Don't Call It LID — They Call It WQMP

If you're building in Orange County or LA County, you've probably been told you need a WQMP. It stands for Water Quality Management Plan, and it's the regional version of what San Diego calls a LID report. Different name, same fundamental requirement: show how your project will treat stormwater before it leaves your site.

A WQMP is the civil engineering document that identifies your project's stormwater pollutant sources, selects appropriate treatment measures (called Best Management Practices or BMPs), sizes them correctly, and documents ongoing maintenance responsibilities.

This document is required for Priority Development Projects (PDPs) and Redevelopment Projects across most of Orange and LA Counties. The building department won't issue permits without an approved WQMP, and you can't get final inspection approval until the BMPs are built and verified.

What's in a WQMP

A complete WQMP addresses stormwater quality from source to discharge:

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Project Description

Site location, project type, total area, impervious area, and drainage characteristics.

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Pollutant Source Identification

Documents which project elements generate stormwater pollutants — roofs, parking, trash areas, landscaping.

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BMP Selection

Identifies which treatment measures will be used — infiltration, biofiltration, proprietary devices, or a combination.

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Sizing & Hydrology

Calculates treatment volume requirements based on the 85th percentile storm and sizes BMPs accordingly.

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Maintenance Plan

Describes inspection frequency, cleaning procedures, and responsible parties for long-term BMP maintenance.

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Certification

Engineer's certification that the WQMP meets the applicable municipal requirements and state regulations.

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Why Every County Has a Version of This

California's Regional Water Quality Control Boards enforce the Clean Water Act through municipal stormwater permits. Every city and county in the state has to comply, which is why you see different names for essentially the same requirement: LID in San Diego, WQMP in Orange and LA Counties, stormwater control plans in the Bay Area.

The underlying driver is the same everywhere: untreated urban runoff pollutes receiving waters, and the state has decided that new development must treat stormwater on-site rather than dumping it straight into storm drains.

Compliance isn't optional. Projects without approved WQMPs don't get building permits. Projects that skip the BMP installation get red-tagged during final inspection. The building department checks this because the Regional Board will fine them if they don't.

When You Need a WQMP?

Common project types and triggers:

Single-Family Hillside Homes

Considered a Priority Development Project in most jurisdictions if located in hillside areas.

New Residential (10+ units)

Always a PDP. Requires full WQMP with treatment BMPs and hydromodification management.

Commercial Development

Almost always a PDP. Parking lots, roofs, and trash areas all require treatment.

Restaurants

PDP due to potential for outdoor dining, trash, and grease. Often requires specialized treatment.

Redevelopment Projects

If you're adding or replacing 5,000+ SF of impervious area, it triggers WQMP requirements even if it's a remodel.

Common Questions

What clients typically ask about a wqmp?:

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