Model Water Efficient Landscape Ordinance

New development and retrofitted landscape water efficiency standards are governed by California's Model Water Efficient Landscape Ordinance (MWELO).

Is My Project Subject to MWELO?

MWELO requirements apply to landscaping projects greater than 500 square feet that require a permit, plan check or design review.

A landscape area includes all the planting areas, turf areas and water features in a landscape design plan.

The landscape area does not include footprints of buildings or structures, sidewalks, driveways, parking lots, decks, patios, gravel or stone walks, other pervious or non-pervious hardscapes, and other non-irrigated areas designated for non-development such as open spaces and existing native vegetation.

Typical permits that would trigger MWELO requirements include a building permit for sprinkler installation, a building permit to construct a swimming pool or a design review application for a building addition.

Santa Rosa Demonstration Garden  2015 Courtesy of the CA Department of Water Resources

My Project is Subject to MWELO. Now What?

On July 15, 2015 the state approved revisions to MWELO, which promotes efficient water use in new and retrofitted landscapes.

To view the revised ordinance in its entirety, please click here.

Below is a summary of the Ordinance: 

1. New Compost & Mulch Requirements. A significant change to the Ordinance includes new requirements for compost and mulch. To improve soil health and increase water retention, at least four cubic yards of compost per 1,000 sq. ft of area must be incorporated into the soil. At least three inches of mulch must be applied to all exposed soil surfaces in planting areas. 

2. Landscape Size Threshold. As of December 1, 2015, the Ordinance will apply to new landscape projects equal to or greater than 500 sq. ft. The Ordinance also applies to rehabilitated landscape projects equal to or greater than 2,500 sq. ft. A prescriptive checklist is available as a compliance option for projects under 2,500 sq. ft.

The following restrictions, including but not limited to the following, as well as irrigation system restrictions, apply to projects using the prescriptive checklist:

Compost: Project must incorporate compost at a rate of at least 4 cubic yards per 1,000 sq. ft. to a depth of 6 inches into landscape area , unless contra-indicated by a soil test.

Residential Plant Water Use: Install climate adapted plants that require occasional, little or no summer water (average Water Use Classification of Landscape Species (WUCOLS) plant factor 0.3) for 75% of the plant area excluding edibles and areas using recycled water.

Plant Use (Non-Residential): Install climate adapted plants that require occasional, little or no summer water (average WUCOLS plant factor 0.3) for 100% of the plant area excluding edibles and areas using recycled water.

Mulch: A minimum 3-inch layer of mulch should be applied on all exposed soil surfaces of planting areas, except in areas of turf or creeping or rooting ground covers.

Turf: Total turf area shall not exceed 25% of the landscape area. Turf is not allowed in non-residential projects. Turf (if utilized) is limited to slopes not exceeding 25% and is not used in parkways less than 10 feet in width. Turf, if utilized in parkways is irrigated by sub-surface irrigation or other technology that prevents over spray or runoff. Turf is not allowed in non-residential projects.

Landscape Water Meter Requirement: Landscape water meters, defined as either a dedicated water service meter or private submeter, shall be installed for all non-residential irrigated landscapes of 1,000 sq. ft. but not more than 5,000 sq.ft. (the level at which Water Code 535 applies) and residential irrigated landscapes of 5,000 sq. ft. or greater. A landscape water meter may be either: 1) a customer service meter dedicated to landscape use provided by the local water purveyor; or a privately owned meter or submeter.

3. Graywater for Irrigation: The Ordinance encourages graywater use.

4. Irrigated Plants in Bio-Retention Basins or Bio-Swales. Plants in bioswales or bioretention basins are not exempt from MWELO. Plants in these drainage systems are regulated for their storm water treatment abilities.

What Do I Need to Do To Be in Compliance?

Streamlined “Prescriptive Compliance Approach” For Projects Less Than 2,500 Sq. Feet

For new and rehabilitated landscapes subject to MWELO and less than 2,500 sq. ft., the streamlined Prescriptive Compliance Approach may be used.

The Prescriptive Compliance Approach is a checklist of landscape standards that are met and documented on the Landscape Plan. These standards include incorporating compost, limiting plant water use, adding mulch, limiting turf area, and requirements for irrigation systems.

Required Forms for Prescriptive Compliance:

• MWELO Project Information Form - To be completed and submitted when applying for a permit.
• MWELO Prescriptive Compliance - Short Form - Items on the checklist are required and must be documented on your submitted landscape plan.

Performance Compliance Approach For Any Size Project and Required For

Projects Greater than 2500 Sq. Feet

For landscapes of any size subject to MWELO, the Performance Compliance Approach can be used, and this approach must be used for landscapes larger than 2,500 sq. ft. The Performance Compliance Approach has additional requirements beyond the Prescriptive Compliance Option. The Performance Compliance Approach must include a soil management report, landscape design plan, irrigation design plan, and a grading design plan. More specifics on the requirements of this approach can be found below in the Landscape Documentation Package Form.

Required Forms for Performance Compliance:

  • MWELO Project Information Form - To be completed and submitted when applying for a permit.
  • MWELO Performance Compliance Checklist
  • MWELO Water Budget Worksheet
  • MWELO Water Budget Worksheet Example
  • MWELO Certificate of Completion Form
  • Landscape Certification Form

Additional Resources

The City of Arcata MWELO Information Handout provides information on revisions to the MWELO and required information to comply with the ordinance.

Information on plant water needs can be found through the Water Use Classification of Landscape Species (WUCOLS) Database.


Please call 707-822-5955 Monday through Friday, between the hours of 9 Am and 5 PM and ask to speak to a planner on duty.