Model Water Efficient Landscape Ordinance

Water Conserving Landscape Photo MWELO
Model Water Efficient Landscape Ordinance (MWELO)

The Model Water Ordinance requires a number of design approaches to maximize water conservation.

MWELO Guidance

MWELO compliance for irrigation projects varies based on local agency and water purveyor requirements. To comply with MWELO on Caltrans irrigation projects follow the following steps.

  1. Check with locals agencies and or local water purveyors for your project to see if this project is required to their local ordinance. If a local ordinance is required follow the local ordinance requirements.
  2. If no local ordinance exists include the following on the irrigation sprinkler schedule sheet.
    1. MAWA Calculation
    2. ETWU Calculation
    3. Hydrozone Information Table
    4. Irrigation Controller Schedule
    5. Pressure Loss Calculations

The information above represents the minimum MWELO and Maintenance requirements for Caltrans projects.


Caltrans projects are required to comply with either the statewide Model Water Efficiency Landscape Ordinance (MWELO), or a local ordinance when required by the local water purveyor.

The purpose of the Model Water Efficiency Landscape Ordinance is to:

  1. Promote the values and benefits of landscapes while recognizing the need to invest water and other resources as efficiently as possible;
  2. Establish a structure for planning, designing, installing, maintaining and managing water efficient landscapes in new construction and rehabilitated projects;
  3. Establish provisions for water management practices and water waste prevention for existing landscapes;
  4. Use water efficiently without waste by setting a Maximum Applied Water Allowance as an upper limit for water use and reduce water use to the lowest practical amount;
  5. Promote the benefits of consistent landscape ordinances with neighboring local and regional agencies; and
  6. Encourage local agencies to enforce the provisions of the Model Water Efficient Landscape Ordinance or their own local landscape ordinance.



Updated: January 11, 2017