Model Water Efficient Landscape Ordinance: Compliance Pathways and Documentation

California’s Model Water Efficient Landscape Ordinance sets the requirements a landscape project must meet to clear building-permit sign-off: a new construction project with 500 or more square feet of landscape area, or a rehabilitated landscape of 2,500 square feet or more, has to submit a compliance package to the local agency, install the landscape to those approved plans, and close out with a Certificate of Completion. Smaller projects on the prescriptive path trade the water-budget math for a design checklist. Everything below walks through what the ordinance actually asks for.

Who the Ordinance Covers

The MWELO applies to landscape work that requires a building permit, landscape permit, plan check, or design review. New construction triggers compliance at 500 square feet of aggregate landscape area. Rehabilitated landscapes trigger it at 2,500 square feet.¹ Residential, non-residential, and public agency projects are all in scope. It doesn’t matter whether a homeowner does the work or hires a licensed contractor.

Several project types are exempt: registered local, state, or federal historic sites; ecological restoration projects without permanent irrigation; mined-land reclamation projects without permanent irrigation; and existing plant collections at botanical gardens and arboretums open to the public.¹ Projects below the square-footage thresholds are also out, though local agencies are free to adopt stricter rules.

The Two Compliance Pathways

Every covered project goes down one of two tracks. The performance pathway requires a full water budget showing the proposed landscape stays within a calculated allowance. The prescriptive pathway swaps that calculation for a design checklist that is deemed to meet the ordinance when followed exactly. The prescriptive option is available only to projects with 2,500 square feet or less of landscape area; anything larger must use the performance pathway.²

One shortcut: a project under 2,500 square feet that meets its entire landscape water need with graywater qualifies for the prescriptive path regardless of other factors and doesn’t need to produce a water budget.¹

What Goes in the Landscape Documentation Package

Projects on the performance pathway submit a Landscape Documentation Package to the local enforcement agency along with the building permit application. The package has to prove, on paper, that the proposed landscape will stay within its water budget.

Water Efficient Landscape Worksheet

The worksheet produces two numbers. The Maximum Applied Water Allowance (MAWA) is the ceiling on annual water use for the site. The Estimated Total Water Use (ETWU) is a prediction of what the proposed plants and irrigation system will actually consume. The ETWU must come in at or below the MAWA.³

Both calculations begin with the reference evapotranspiration rate (ETo) for the project’s location, which measures how much water a well-watered lawn would need in that climate. Appendix C of the ordinance supplies ETo values for cities across California. The MAWA formula then applies an ET Adjustment Factor that caps water use at 0.55 for residential landscapes and 0.45 for non-residential landscapes.¹ A residential project can use at most 55% of what a pure lawn would require in its climate zone.

Special Landscape Areas get a more generous ETAF of 1.0. These include areas planted with edibles like vegetable gardens and orchards, active recreation areas, and any area irrigated with recycled water.¹ Dedicating part of the site to edibles raises the allowance for that portion without disqualifying the rest.

The ETWU side works from the plants outward. Each hydrozone gets a plant factor from the WUCOLS database and an irrigation efficiency value, which the MWELO sets at 0.75 for overhead sprinklers and 0.81 for drip systems.⁴ Low-water plants and efficient irrigation drive the ETWU down.

Landscape Design Plan

The landscape design plan identifies every plant by species, marks its location, and categorizes it by water need. It must show how plants are grouped into hydrozones so species with similar water requirements share irrigation valves. A licensed landscape architect, licensed landscape contractor, or another person authorized by law to design landscapes must sign it.¹

Irrigation Design Plan

The irrigation design plan details the hardware: controller type, sprinkler heads, drip emitters, pressure regulators, and flow sensors. Controllers must use evapotranspiration or soil moisture sensor data and include a rain sensor. A manual shut-off valve must sit as close as possible to the water supply connection. Any planting area narrower than ten feet has to use subsurface irrigation or another method that eliminates runoff and overspray.¹ A licensed landscape architect, certified irrigation designer, or licensed landscape contractor must sign the plan.

Grading Design Plan

The grading design plan shows finished elevations, slope heights, drainage patterns, and any stormwater retention improvements. The point is to keep irrigation water and rainfall on the property. A licensed professional must sign it, and a comprehensive grading plan already prepared by a civil engineer for other permits will satisfy the requirement.¹

Soil Management Report

Every project needs a soil management report based on lab analysis. Samples must be tested for texture, infiltration rate, pH, total soluble salts, sodium, and percent organic matter, and the lab has to provide recommendations.¹ If the project doesn’t involve significant mass grading, the report goes in with the Landscape Documentation Package. If major grading is planned, it can be submitted later with the Certificate of Completion. For large developments, sampling one in seven lots (roughly 15%) satisfies the requirement.

Beyond testing, the ordinance requires compost incorporated at a rate of at least four cubic yards per 1,000 square feet of permeable area, worked into the top six inches of soil. Soils already containing more than 6% organic matter in the top six inches are exempt.¹

The Prescriptive Checklist for Smaller Projects

Projects with 2,500 square feet or less of landscape can skip the water-budget math and follow a prescriptive checklist. This is common for single-family homes and light commercial work.² The plant and turf rules split by property type:

Residential: at least 75% of the planted area must be climate-adapted plants that need little or no summer water, and turf cannot exceed 25% of the landscape area.
Non-residential: 100% of the planted area must be low-water climate-adapted plants, and turf is prohibited entirely.

Edible plants and areas irrigated with recycled water are excluded from these percentage calculations.¹

Where turf is allowed, it can’t go on slopes steeper than 4:1, and turf in parkways narrower than ten feet must use subsurface irrigation. A minimum three-inch mulch layer is required on all exposed soil in planting areas, except where turf, creeping groundcovers, or direct seeding makes mulch impractical.¹

Irrigation systems on the prescriptive path must use automatic controllers running on evapotranspiration or soil moisture sensor data, plus a rain sensor. Controllers must retain their programming through a power interruption. Pressure regulators are required, and all sprinkler heads must meet the ASABE/ICC 802-2014 standard with a distribution uniformity of 0.65 or higher.¹ The same compost rule applies: four cubic yards per 1,000 square feet to a six-inch depth, unless soil testing says otherwise.

Who Must Sign Each Component

The MWELO is specific about who can certify each piece, and getting a signature from the wrong credential is a common reason for rejection. Confirm credentials before submitting.

Landscape design plan: licensed landscape architect, licensed landscape contractor, or another person authorized by law to design landscapes.
Irrigation design plan: licensed landscape architect, certified irrigation designer, or licensed landscape contractor.
Grading design plan: a licensed professional authorized by law; a civil engineer’s grading plan prepared for other permits counts.
Certificate of Completion: the signer of the landscape design plan, the signer of the irrigation design plan, or the licensed landscape contractor who installed the project.
Irrigation audit: a certified landscape irrigation auditor who was not involved in designing or installing the landscape.

The independence rule on the irrigation auditor catches people off guard. The person who designed or installed the system can’t audit it, even with the right certification.¹ For large developments with multiple lots, auditing one in seven installations (about 15%) satisfies the requirement.

The Certificate of Completion

After the local agency approves the documentation package and the landscape is installed, the project closes out with a Certificate of Completion proving the finished work matches the approved plans. It has to include six elements:¹

A project information sheet with date, project name, applicant contact information, project address, and property owner contact information.
A signed professional certification confirming the project was installed per the approved plans, with as-built drawings for any significant field changes.
The irrigation scheduling parameters programmed into the controller.
A written maintenance schedule for the landscape and irrigation system.
The irrigation audit report from the independent certified auditor.
The soil analysis report, if not already submitted, plus proof that its recommendations were followed.

The property owner signs the certificate too, acknowledging receipt of the full package and accepting responsibility for maintenance.⁵ The local agency then approves or denies the certificate. A denial must come with information about reapplication or appeal options. Copies of the approved certificate go to the local water purveyor and the property owner, and a hydrozone diagram should be kept with the irrigation controller for future managers of the system.¹

Ongoing Maintenance After Sign-Off

Compliance doesn’t end with the Certificate of Completion. The maintenance schedule filed with it becomes a binding commitment. Property owners have to keep irrigation equipment working, adjust watering schedules seasonally, maintain soil health, and replace dead plants with species of similar or lower water use.² The schedule must include routine inspection, auditing, adjustment, and repair of the irrigation system.

Enforcement

The MWELO delegates enforcement to local agencies. Each one sets its own penalties for non-compliance to the extent allowed by law, and penalties for water-waste violations like runoff and overspray are also set locally.¹ The consequences for skipping compliance vary by jurisdiction. Common tools are withholding building permit sign-off, denying certificates of occupancy, and requiring corrective work before a project can close out.

Note that stormwater capture features are recommended rather than required under the MWELO itself. Local agencies and Regional Water Quality Control Boards may impose their own stormwater requirements independently, so check with the local agency before assuming the ordinance text is the full picture.¹

1
California Department of Water Resources. Model Water Efficient Landscape Ordinance
2
California Department of Water Resources. Model Water Efficient Landscape Ordinance Guidebook
3
Legal Information Institute. California Code of Regulations Title 23, Division 2, Chapter 2.7, Appendix A – Sample Water Efficient Landscape Worksheet
4
California Department of Water Resources. Landscape Irrigation Water Budget Overview
5
California Department of Water Resources. Certificate of Completion