1. (a) A project applicant shall complete the Water Efficient Landscape Worksheet in Appendix A, which compares the landscape project's Estimated Total Water Use (ETWU) with the Maximum Applied Water Allowance (MAWA). ETWU must be equal to or below the MAWA.

   1. (1) The MAWA is calculated based on the maximum ETAF allowed for the landscape project and is expressed as annual gallons allowed. The maximum ETAF allowed is:

      1. (A) 0.55 for residential regular landscape areas,
      2. (B) 0.45 for non-residential regular landscape areas,
      3. (C) 1.0 for new and existing (non-rehabilitated) Special Landscape Areas.
   2. (2) The ETWU is the sum of estimated water use (EWU) for each hydrozone. The evapotranspiration adjustment factor (ETAF) for each hydrozone is based on the plant factor and the average irrigation system efficiency. EWU is calculated using the ETAF, regular landscape areas, and the special landscape areas.
   3. (3) In calculating the Maximum Applied Water Allowance and Estimated Total Water Use, a project applicant shall use the ETo values from the Reference Evapotranspiration Table in Appendix C. For geographic areas not covered in Appendix C, use data from other cities located nearby in the same reference evapotranspiration zone, as found in the CIMIS Reference Evapotranspiration Zones Map, Department of Water Resources, 1999, which is herein incorporated by reference.

2. (b) Water budget calculations shall adhere to the following requirements:

   1. (1) The plant factor used shall be from WUCOLS or from horticultural researchers with academic institutions or professional associations as approved by the California Department of Water Resources. The plant factor ranges are:

      1. (A) less than 0.1 for very low water using plants,
      2. (B) 0.1 to 0.3 for low water use plants,
      3. (C) 0.4 to 0.6 for moderate water use plants,
      4. (D) 0.7 to 1.0 for high water use plants.
   2. (2) All water features shall use the high water use plant factor in the water budget calculations.
   3. (3) Temporarily irrigated areas shall use the low water use plant factor in the water budget calculations.
   4. (4) All Special Landscape Areas (SLA) shall be identified in the Landscape Design Plan (Section 493.2) and the Irrigation Design Plan (Section 493.2.2) and their water use calculated as shown in Appendix A.

   5. (5) A local agency may consider Effective Precipitation (Eppt), (25% of annual precipitation) in tracking water use and may use the following equation to calculate Maximum Applied Water Allowance:

      1. (A) Residential landscapes:

         MAWA = (ETo - Eppt) x (0.62) x [0.55 x RLA + 1.0 x SLA].

      2. (B) Non-residential landscapes:

         MAWA = (ETo - Eppt) x (0.62) x [0.45 x RLA + 1.0 x SLA].

Note: Authority cited: Sections 65596 and 65596.5, Government Code. Reference: Sections 65593, 65596 and 65596.5, Government Code.

History

1. New section filed 1-2-2025; operative 1-2-2025 pursuant to Government Code section 11343.4(b)(3) (Register 2025, No. 1).