California's Water Efficient Landscape Ordinance (WELO) establishes standards for water-efficient landscaping in new and renovated landscapes. It establishes minimum water efficiency standards that apply across California to qualifying residential, commercial, institutional, and public projects.
The ordinance promotes healthy landscapes that reduce water waste through appropriate plant selection, efficient irrigation, and the use of compost and mulch to improve soil health and water retention.
Compost and mulch play a central role in WELO compliance by improving soil structure, reducing evaporation, and decreasing overall irrigation needs.
Applicability
WELO applies to projects requiring permits, plan checks, or design reviews that meet specific size thresholds:
- New construction: Landscapes exceeding 500 square feet
- Existing landscape renovations: Areas larger than 2,500 square feet
Certain properties, including arboretums and registered historical sites, are exempt from compliance.
Key Requirements
- Water budget calculations based on local climate data and plant water needs
- Use of compost and mulch to improve soil health and reduce irrigation requirements
- Efficient irrigation system design and installation
- Appropriate plant selection for local climate conditions
Enforcement
Local jurisdictions — cities, counties, and some water agencies — enforce WELO requirements. Before starting your project, check with the local reviewing agency, as regional requirements may differ.
Exceeding Minimum Standards
Property owners seeking to exceed minimum WELO standards can pursue ReScape California Rated Landscape certification for higher environmental performance recognition.
Related Resources
- WELO Toolkit — implementation tools and calculators
- Trainings for Landscape Professionals — enforcement training materials
- Rules & Compliance section — full regulatory details
