California Water Efficient Landscape Ordinance

WUCOLS
Decoded.
Complied.

WUCOLS is the official California plant water-use classification system behind every MWELO submission. If you need a landscape permit, WUCOLS data decides if you pass — or don't.

Validate on MWELO.com What is WUCOLS?

MWELO Compliance Tool Powered by WUCOLS Data

The database behind every permit

What Is WUCOLS?

WUCOLS — Water Use Classification of Landscape Species — is California's official database of plant water requirements. Developed by UC Cooperative Extension and the California Department of Water Resources, it classifies thousands of plants into water-use categories by region.

Every MWELO landscape compliance document relies on WUCOLS data to calculate your project's water budget. No WUCOLS, no permit.

VERY LOW WATER

Hydrozone 1 — <10" annual ETo

LOW WATER

Hydrozone 2 — core MWELO zone

MODERATE WATER

Hydrozone 3 — requires justification

Four steps. One compliance document.

How WUCOLS Becomes Your Permit

Look Up Your Plants

WUCOLS classifies thousands of species by water need and California region. Every plant on your plan needs a classification.

Assign Hydrozones

Group plants by water use into hydrozones. Each zone gets a budget based on ETo data for your specific address.

Calculate the Budget

MWELO math: applied water ≤ MAWA. Your design must stay within the Maximum Applied Water Allowance for the site.

Submit. Pass. Build.

A validated MWELO document unlocks your construction permit. MWELO.com automates steps 1–3 in minutes.

WUCOLS-Classified Plants That Work

Low Water. Full Compliance.

PALO VERDE

Zero Water. Full Presence. WUCOLS VL.

AGAVE

Zero Water. Zero Apologies. WUCOLS VL.

LAVENDER

Mediterranean Soul. California Compliant. WUCOLS L.

FRUITLESS OLIVE

Silver Leaves. Zero Water. WUCOLS VL.

SALVIA APIANA

White Sage. Sacred, Native, Compliant. WUCOLS VL.

DESERT WILLOW

The Flowering Tree the Desert Actually Grows. WUCOLS VL.

Look up any plant in the full WUCOLS database → MWELO.com

WUCOLS Data · MWELO Compliance

Your Landscape Permit
Starts Here.

Stop wrestling spreadsheets and ordinance PDFs. MWELO.com reads every WUCOLS classification, pulls your address's ETo data, and produces a permit-ready compliance document in minutes.

Validate at MWELO.com

www.mwelo.com — California's MWELO Compliance Tool

Common questions

WUCOLS & MWELO, Explained Fast

What is MWELO and why do I need it?

MWELO — the Model Water Efficient Landscape Ordinance — is California's statewide regulation requiring water-efficient landscape plans for new construction, major renovations, ADUs, pools, and many commercial projects over 500 sq ft of irrigated area. A validated MWELO document is required before your building permit can be issued.

How does WUCOLS connect to my permit?

Every plant in your design must have a WUCOLS water-use factor assigned. These factors are used to calculate your project's annual water budget. If your design's water demand exceeds the MAWA (Maximum Applied Water Allowance) for your site, you cannot obtain a permit — period.

Who needs to submit a MWELO document?

Landscape architects, contractors, developers, and homeowners pulling permits for: new builds, ADUs, home additions, pool installations, turf conversions, or any project where the landscape area (irrigated) is ≥500 sq ft. Many California cities apply it to smaller projects too. When in doubt, assume it applies.

What does MWELO.com actually do?

MWELO.com automates the entire compliance calculation. Enter your address, input your plant list and areas, and the tool retrieves local ETo data, applies WUCOLS classifications, runs the water budget math, and generates a compliant MWELO document — ready to submit to your city. No spreadsheets. No math errors. No back-and-forth with the plan checker.

Does MWELO.com cover my city?

MWELO.com covers all California jurisdictions — every county and incorporated city. The tool uses address-specific CIMIS ETo data, so your water budget is calculated for the exact microclimate of your project site, not a regional average.