May 22, 2026·7 min read

MWELO Compliance Checklist California: A Firm's Guide

A practical MWELO compliance checklist for California landscape architects covering documentation, calculations, and submission requirements that pass agency review.

California's Model Water Efficient Landscape Ordinance has been mandatory for qualifying projects since 2010, updated significantly in 2015, and yet agencies still kick back submittals for the same preventable errors. If you're using this MWELO compliance checklist for California projects, you already know the regulation exists — what you need is a practical sequence that gets documents approved on the first pass.

Who MWELO Actually Applies To

The 2015 update lowered the threshold to 500 square feet of irrigated landscape for new construction and rehabilitated projects. That catches a lot of work that firms used to treat as exempt. Projects on single-family residential lots where the homeowner signs a MWELO compliance agreement shift some documentation responsibility to the owner, but your firm still needs to produce the Landscape Documentation Package before permits issue.

Local agencies can adopt their own ordinances that are at least as restrictive as the state model. Los Angeles, San Diego, and the Bay Area water districts each have variations — some require additional soil analysis, some use different evapotranspiration reference sources. Before you build your checklist for any given project, confirm whether the local agency has an adopted ordinance or defaults to the state model. That distinction changes your submittal package.

The Landscape Documentation Package: What It Must Contain

The LDP is the core deliverable. It has five required components: the project information form, the water efficient landscape worksheet (which includes the ETWU and MAWA calculations), the soil management report, the landscape design plan, and the irrigation design plan. Miss one and the submittal is incomplete by definition.

The project information form is straightforward but gets skipped when teams are rushing. It requires the project applicant's contact information, the local agency's contact, and the water supplier's name. The water supplier detail matters because your ETWU calculation depends on the correct ET₀ reference value, which varies by water district and sometimes by zip code within a district.

ETWU and MAWA Calculations Done Correctly

The Estimated Total Water Use and Maximum Applied Water Allowance calculations are where most technical errors occur. MAWA is calculated as: (ET₀ × 0.62) × [(0.7 × LA) + (0.3 × SLA)], where LA is the total landscape area and SLA is the special landscape area. ETWU uses plant factor and irrigation efficiency values that have to match what's actually specified on the plan.

The 0.7 hydrozone factor applies to standard plantings. Special landscape areas — edible gardens, recreational turf, water features — use a 1.0 factor and get calculated separately. Firms routinely misclassify recreational turf or forget to break out the SLA entirely, which either inflates the allowance artificially or triggers a flag during agency review. Your ETWU must be equal to or less than the MAWA. If it isn't, the plant palette or irrigation design has to change before submission — not after.

Soil Management Report Requirements

The soil management report is required for all projects unless the project applicant provides documentation that no soil amendment is needed. In practice, that exemption is rarely used because it requires a written statement from a licensed professional. The report must include a soil analysis and a soil management plan.

The soil analysis needs to cover soil texture, infiltration rate, pH, total soluble salts, sodium, and percent organic matter. These aren't optional line items. The management plan then specifies amendments — compost, gypsum, sulfur — based on the analysis results. Specify the application rate in cubic yards per 1,000 square feet. Vague language like "amend as needed" will get the submittal returned.

Irrigation Plan Checklist Details

The irrigation plan is where the field meets the paperwork. It has to show the location of all irrigation components, the irrigation schedule, and the controller type. But it also requires the precipitation rate for each valve circuit, the irrigation efficiency of the system, and the maximum applied water use by hydrozone.

Drip systems and spray systems on the same valve are a common field shortcut that violates MWELO. Each hydrozone needs to have matched precipitation rates and similar plant water needs. If your design shows mixed emitter types on a single zone, expect a correction notice. Smart controllers need to be listed by make and model, and the model needs to appear on the SWRCB's approved product list if the project is claiming any credit for controller efficiency.

Post-Installation Certificate of Completion

The Certificate of Completion is submitted after installation and before final inspection. It certifies that the installed landscape matches the approved LDP. The person who signs it — typically the licensed landscape architect or contractor — is attesting that the irrigation system was installed per the plan, the controller is programmed to the approved schedule, and the plant species and locations match the design.

This is where projects fall apart operationally. The contractor installs something different — a substituted plant species, a relocated valve, a different controller model — and nobody updates the as-built documentation. Your firm gets the call when the inspector flags a discrepancy at final. Build a field verification step into your project closeout sequence. A single site visit before the certificate is signed catches most of these problems.

Common Mistakes Firms Make

Using the wrong ET₀ value. The CIMIS reference ET₀ varies by station and by month. Using a statewide average instead of the station closest to the project site produces a MAWA that doesn't match what the agency expects. Some agencies specify which CIMIS station to use — check before you calculate.

Forgetting the soil report on small projects. Teams treat the soil management report as a large-project requirement. The 500 sq ft threshold means it applies to projects that feel minor. A 600 sq ft courtyard renovation still needs the full report unless you have a written exemption.

Submitting the irrigation plan without hydrozone calculations. The plan needs to show ETWU by hydrozone, not just a single project total. Agencies reviewing the submittal check that each hydrozone's water use is consistent with the plant factor and precipitation rate shown.

Misidentifying special landscape areas. A client's kitchen garden is a special landscape area. A putting green is a special landscape area. Misclassifying these as standard landscape inflates your MAWA, which can make a non-compliant design appear compliant on paper — until the agency's reviewer catches it.

Signing the Certificate of Completion without a field verification. This is a liability issue as much as a compliance issue. If the installed irrigation doesn't match the approved plan, your signature on the certificate is inaccurate. Contractors make substitutions constantly. You need eyes on the site before you sign.

Not tracking local amendments. The state model is the floor. Some agencies require additional documentation — a separate water budget worksheet, a licensed agronomist's signature on the soil report, or a specific submittal portal. Treating every project as a state-model submission without checking local requirements adds correction rounds that cost real time.

How Phasewise Handles This

Phasewise lets you build a reusable MWELO compliance checklist template that attaches to every qualifying project at the start of design. Each checklist item — ET₀ source confirmation, SLA classification, soil report status, irrigation hydrozone calculations, Certificate of Completion sign-off — can be assigned to a specific team member with a due date tied to the project phase. When the contractor makes a field substitution, the task to update the as-built and re-verify the certificate is already in the system waiting to be triggered. It doesn't replace your technical judgment, but it does mean nothing falls through the cracks between the design team and the project manager at closeout.