TO: Napa County Planning Commission
FROM: Brian D. Bordona - Director of Planning, Building and Environmental Services
REPORT BY: Emily Hedge, Planner III
SUBJECT: Proposed Updates to Zoning Code Chapter 18.118 Water Conservation Regulation for Landscape Design
RECOMMENDATION
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Request: Discussion and recommendation that the Board of Supervisors adopt an ordinance amending Chapter 18.118 (Water Conservation Regulations for Landscape Design) of Title 18 (Zoning) of the Napa County Code to achieve consistency with the California Code of Regulations Title 23, Division 2, Chapter 2.7 Model Water Efficiency Landscape Ordinance.
CEQA Status: Pursuant to Categorical Exemption Class 8 (“Actions by Regulatory Agencies for the Protection of the Environment”) which may be found in the guidelines for the implementation of the CEQA at 14 CCR §15308; and the General Rule in that it can be seen with certainty that there is no possibility the proposed action may have a significant effect on the environment and therefore the CEQA is not applicable. [See Guidelines for the Implementation of the CEQA 14 CCR §15061(b)(3).].
Staff Recommendation: That the Planning Commission make a recommendation to the Board of Supervisors on the proposed amendments to Title 18 of the Napa County Code identified above.
Staff Contact: Emily Hedge, Planner III, (707) 259-8226, emily.hedge@countyofnapa.org
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EXECUTIVE SUMMARY
Proposed Actions:
That the Planning Commission:
1. Recommend the Board of Supervisors find the proposed amendments exempt from the California Environmental Quality Act pursuant to Categorical Exemption Class 8 (“Actions by Regulatory Agencies for the Protection of the Environment”) which may be found in the guidelines for the implementation of the CEQA at 14 CCR §15308; and the General Rule in that it can be seen with certainty that there is no possibility the proposed action may have a significant effect on the environment and therefore the CEQA is not applicable [See Guidelines for the Implementation of the CEQA 14 CCR §15061(b)(3).] and;
2. Recommend the Board of Supervisors adopt an ordinance amending Chapter 18.118 (Water Conservation Regulations for Landscape Design) of Title 18 (Zoning) of the Napa County Code to achieve consistency with the California Code of Regulations Title 23, Division 2, Chapter 2.7 Model Water Efficiency Landscape Ordinance.
Discussion:
The California Department of Water Resources (DWR) Model Water Efficient Landscape Ordinance (MWELO) is a statewide water efficiency regulation for new development and retrofitted landscapes in California. The MWELO provides definitions, technical information, and sample documents for the development of water efficient landscapes. All local agencies must adopt, implement, and enforce the MWELO or a local Water Efficient Landscape Ordinance that is at least as efficient as the MWELO. In 1992, the County adopted its own provisions through Napa County Code (NCC) Chapter 18.118 and Landscape Guidelines by Resolution. These documents have not been amended to date. Since the NCC has not been updated to stay current with State code, there are portions of the code that are no longer “as efficient” as the MWELO. Therefore, Staff recommends that the Planning Commission hold a public hearing, solicit comments, discuss, and make a recommendation that the Board of Supervisors adopt the proposed revisions to the existing NCC provisions. Following the Planning Commission recommendation, the ordinance will be scheduled for consideration by the Board of Supervisors. A public notice will be provided at least twenty days in advance of the hearing before the Board of Supervisors.
ENVIRONMENTAL IMPACT
ENVIRONMENTAL DETERMINATION: Pursuant to Categorical Exemption Class 8 (“Actions by Regulatory Agencies for the Protection of the Environment”) which may be found in the guidelines for the implementation of the CEQA at 14 CCR §15308; and the General Rule in that it can be seen with certainty that there is no possibility the proposed action may have a significant effect on the environment and therefore the CEQA is not applicable. [See Guidelines for the Implementation of the CEQA 14 CCR §15061(b)(3).].
BACKGROUND AND DISCUSSION
State Requirement
The California Department of Water Resources (DWR) Model Water Efficient Landscape Ordinance (MWELO) is a statewide water efficiency regulation for new development and retrofitted landscapes in California. The text of California Code of Regulations (CCR) Title 23, Division 2, Chapter 2.7 Model Water Efficiency Landscape Ordinance can be viewed online through a link on the DWR website - https://water.ca.gov/Programs/Water-Use-And-Efficiency/Urban-Water-Use-Efficiency/Model-Water-Efficient-Landscape-Ordinance. The MWELO is also referenced by Title 24, Part 11, Chapters 4 and 5 CalGreen Building Code.
The MWELO is a model for local agencies to enforce minimum standards for water use efficiency in landscape design, construction, and management. It achieves this through specific requirements related to soil, plants, irrigation, stormwater, and nonpotable water supplies to improve California’s conditions in the built environment and provide benefits and realize sustainability goals. The MWELO provides definitions, technical information, and sample documents for the development of water efficient landscapes. All local agencies must adopt, implement, and enforce the MWELO or a local Water Efficient Landscape Ordinance that is at least as efficient as the MWELO.
Background
In 1992, the Napa County Board of Supervisors adopted Ordinance No. 1029 to add Napa County Code (NCC) Chapter 18.118 (Water Conservation Regulation for Landscape Design), outlining a water conservation program for Napa County. This local program was implemented through Landscape Guidelines adopted by Resolution No. 92-161 (Attachment C). The 1992 resolution states that circumstances of Napa County suggest that a locally-designed ordinance would provide greater benefit to the public of Napa County, rather than a generic ordinance designed for all situations in the state.
Chapter 18.118 of the NCC and the Landscape Guidelines have not been amended since 1992, while DWR amended portions of the MWELO in 2009 and 2015, and most recently, in January 2025, DWR issued a rulemaking revising the MWELO Regulations and Appendices. Since the NCC has not been updated to stay current with State code, there are portions of the NCC that are no longer “as efficient” as the MWELO.
The law directs land use authorities to ensure MWELO compliance on development projects with landscaped areas of 500 square feet or more for new construction projects and 2,500 square feet or more for rehabilitated landscape projects. This applies to residential, commercial, industrial, and institutional projects that require a building or landscape permit, plan check, or design review. To comply with new landscape water efficiency standards, County staff currently direct members of the public to prepare landscape plans in accordance with the MWELO and does not utilize Chapter 18.118, nor the County adopted Landscape Guidelines.
While the NCC and Landscape Guidelines contain much of the same definitions, formulas, and required information, the MWELO contains more detailed calculation factors, up-to-date equipment based on industry standards, and standard sources for data, such as water use associated with plant and landscape types. Additionally, the revised MWELO includes significantly more local information than it originally did. The location data provided for Napa County in the MWELO exceeds the specific location data included in the Landscape Guidelines. The additional detail allows for more precise calculations and operational standards.
A few examples of differences between current MWELO and NCC include:
Applicability of Project Types
• MWELO - Applies to residential, commercial, industrial, and institutional projects that require a building or landscape permit, plan check, or design review.
• NCC - The County code lists “Homeowner-provided landscaping for single-family and multifamily projects” as exempt from evaluation under the County Landscape Guidelines.
Local Reference Data - The “reference evapotranspiration” or “ETo”, is a standard measurement of environmental parameters which affect the water use of plants.
• MWELO - Appendix C. Reference Evapotranspiration (ETo) includes 12 locations throughout the County. Napa County, American Canyon, Angwin, Calistoga, Deer Park, Moskowite Corner, Napa, Oakville, Rutherford, Silverado Resort, St. Helena, Yountville.
• NCC - Landscape Guidelines include three (3) locations, one of which is in Solano County. St. Helena, Yountville, Benicia (Solano County)
Plant Factor Categories - “Plant Factor” is a factor, when multiplied by ETo, estimates the amount of water needed by plants.
• MWELO - Includes four categories - very low, low, moderate, and high water use plants
• NCC - Includes two categories - low and high
ET adjustment factor (ETAF) Calculations - ETAF means a factor that, when applied to reference evapotranspiration, adjusts for plant factors and irrigation efficiency, two major influences upon the amount of water that needs to be applied to the landscape.
• MWELO - Includes separate calculations for residential, non-residential, “special landscape areas”, and existing non-rehabilitated landscape areas.
• NCC - Includes one (1) factor for all project types.
Irrigation Efficiency Rates - “Irrigation Efficiency” (IE) means the measurement of the amount of water beneficially used divided by the amount of water applied and is expressed as a percentage. Irrigation efficiency is derived from measurements and estimates of irrigation system characteristics and management practices.
• MWELO - Contains separate rates for overhead and drip irrigations systems. The rates are based on higher efficiency equipment and operations.
• NCC - Contains one (1) rate.
Proposed Text Amendment
Attachment A “Proposed Ordinance - Redlined” presents the proposed edits, shown in strikethrough and underline. The primary proposed change is to include direct references to California Code of Regulations (CCR) Title 23, Division 2, Chapter 2.7. Attachment B “Proposed Ordinance - Clean” shows the final ordinance language, should the ordinance be amended as proposed.
Since the MWELO is comprehensive and covers the requirements currently included in NCC 18.118, most of the individual lists of requirements can be removed, resulting in a more concise code section. County specific regulations regarding violations (NCC Sec.18.118.040 - Violations) remain unchanged.
The provisions of Napa County Board of Supervisors Resolution No. 92-161 would be repealed in their entirety. The Napa County Water Conservation in Landscape Guidelines would be replaced with the requirements provided in the MWELO.
Benefits
In addition to ensuring compliance with State standards, the updated code will result in the following benefits:
• The use of standardized documents simplifies the review process for staff. MWELO includes Appendix A. Sample Water Efficient Landscape Worksheet and Appendix B. Sample Certificate of Completion Package.
• More efficient documentation for the required annual reporting to DWR. Local agencies are required to report on implementation annually by January 31 of each year to DWR’s Water Use Efficiency Branch.
• The direct reference to the CCR ensures that code language does not become inconsistent with State regulations or requirements.
• The direct reference to the CCR removes the need to go through the Text Amendment process to update County code following future revisions to the MWELO. The DWR’s mandatory three-year update cycle begins January 1, 2026.
Additional Information
Today’s public hearing was noticed in the Napa Valley Register on Thursday, November 20, 2025. The same notice was also emailed out to the County’s Interested Parties List that same day. At the time of publishing, staff have not received any public comment.
Recommendation
Discussion and recommendation that the Board of Supervisors adopt an ordinance amending Chapter 18.118 (Water Conservation Regulations for Landscape Design) of Title 18 (Zoning) of the Napa County Code to achieve consistency with the California Code of Regulations Title 23, Division 2, Chapter 2.7 Model Water Efficiency Landscape Ordinance. The Board of Supervisors will hold a public hearing to consider the Planning Commission’s recommendation and vote on adoption. A public notice will be provided at least twenty days in advance of the hearing before the Board of Supervisors.
Decision Making Options:
Option 1 - Forward a recommendation of approval of amendments to NCC Section 18.118 Water Conservation Regulations for Landscape Design (staff recommendation).
Option 2 - Forward a recommendation of approval of “Revised” amendments to NCC Section 18.118 Water Conservation Regulations for Landscape Design.
Option 3 - Forward Recommendation to Deny the Proposed amendments to NCC Section 18.118 Water Conservation Regulations for Landscape Design.
Option 4 - Continuance Option
ATTACHMENTS:
A. Proposed Ordinance - Redlined
B. Proposed Ordinance - Clean
C. Resolution No. 92-161 and Landscape Guidelines