TO: Napa County Planning Commission
FROM: Brian D. Bordona, Director of Planning, Building and Environmental Services
REPORT BY: Emily Hedge, Planner III - (707) 259-8226
SUBJECT: Castello di Amorosa Winery, Use Permit Major Modification Application #P19-00459-MOD and Appeal #P25-00137 Groundwater Review
RECOMMENDATION
title
DARIO SATTUI / CASTELLO DI AMOROSA / ADVISORY REPORT FOR USE PERMIT MAJOR MODIFICATION APPLICATION #P19-00459-MOD AND APPEAL #P25-00137
CEQA Status: Consideration of a revised Categorical Exemption Memorandum, determining that the project is categorically exempt from the California Environmental Quality Act (CEQA). It has been determined that this type of project does not have a significant effect on the environment and is exempt from CEQA. The project will not impact an environmental resource of hazardous or critical concern, has no cumulative impact, there is no reasonable possibility that the activity may have a significant effect on the environment due to unusual circumstances, will not result in damage to scenic resources, is not located on a list of hazardous waste sites, or cause substantial adverse change in the significance of a historical resource. As proposed the project meets the criteria for eligibility as Categorically Exempt from CEQA under Classes 1, 2, 3, 4, and 11. [See Class 1 (“Existing Facilities”), Class 2 (“Replacement or Reconstruction”), Class 3 (“New Construction or Conversion of Small Structures”), Class 4 (“Minor Alterations to Land”), and Class 11 (“Accessory Structures”) which may be found in the guidelines for the implementation of the CEQA at Title 14 CCR §15301, §15302, §15303, §15304, and §15311]. The project site is not included on a list of hazardous materials sites compiled pursuant to Government Code Section 65962.5.
Request: As directed by the Board of Supervisors on remand of Appeal File No. P25-00137, the Planning Commission will review groundwater related matters including, but not limited to, the updated Water Availability Analysis, staff’s revised analysis of groundwater use, revised CEQA Memorandum, and Revised Recommended Conditions of Approval. Upon consideration of these matters the Planning Commission will forward an advisory recommendation to the Board of Supervisors. The pending appeal on the Castello di Amorosa Winery project will then be noticed for a hearing before the Board of Supervisors. Public notice of the appeal hearing will be provided at least 19 days in advance of the hearing.
The Winery Parcel is located on an approximately 40-acre parcel at 4045 North St. Helena Highway. The parcel is within the AW (Agricultural Watershed) zoning district, with a General Plan designation AWOS (Agriculture, Watershed and Open Space). Winery Parcel APN 020-390-012 (SFAP) and Residential Parcel APN 020-230-001 (SFAP).
Staff Recommendation: That the Planning Commission issue an advisory recommendation to the Board of Supervisors with the following recommendations from Staff: find the Project Categorically Exempt from CEQA and approve Use Permit Modification P19-00459, subject to the Revised Recommended Conditions of Approval.
Staff Contact: Emily Hedge, Planner III, (707) 259-8226 or emily.hedge@countyofnapa.org
Applicant Contact: Dario Sattui, (707) 967-6260 or dario@castellowines.com
Project Agent: Georg Salzner, (707) 967-6261, georg@castellodiamorosa.com
Applicant Representative: Scott Greenwood-Meinert, (415) 772-5741, sgreenwood-meinert@coblentzlaw.com
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EXECUTIVE SUMMARY
Proposed Actions:
That the Planning Commission recommend that the BOS:
1. Find the project Categorically Exempt from CEQA; and
2. Approve Use Permit Modification P19-00459 subject to the Revised Recommended Conditions of Approval in Attachment B.
Discussion:
On April 2, 2025, the Napa County Planning Commission (“Commission”) approved the Castello Di Amorosa Winery Use Permit Major Modification No. P19-00459, to recognize and approve items that are out of compliance with the permitted entitlements and for an expansion beyond existing entitlements. The application was enrolled in the County’s Use Permit Compliance Program. The Commission found the project categorically exempt from the CEQA (under Classes 1, 2, 3, 4, and 11) and approved the Use Permit Major Modification.
The Commission approved the project with three (3) revised conditions of approval and added one new condition regarding groundwater use. The new condition was added by the Commission and agreed to by the applicant to ensure groundwater levels and the pump rate for the non-project well (Well #2) were maintained at baseline conditions in perpetuity. To determine baseline conditions, the Applicant was directed to provide prior year and current monthly and annual groundwater use from Well #2 to be included in the final condition of approval.
On April 16, 2025, a timely notice of intent to appeal the Commission’s decision on the Use Permit Major Modification was filed by Water Audit California (WAC) and a timely appeal packet was submitted on April 30, 2025 (the Appeal P25-00137). On April 21, 2 025, approximately three weeks after the Commission decision on the Project and after the notice of intent to appeal was filed, the Applicant provided the required monthly water usage for 2024 and for part of 2025 for the two wells and the reservoir on the property. Upon review of this baseline data, staff discovered discrepancies between the information provided and what was disclosed in the Applicant’s WAA that was considered by the Commission. Specifically, the Applicant’s baseline data revealed that groundwater pumped from Well #2 greatly exceeded the total groundwater water use disclosed in the Applicant’s WAA by almost double in year 2024 and was close to the annual rate of recharge for the property. This data further revealed additional significant discrepancies in the Applicant’s WAA, leading staff to conclude that the Applicant’s WAA relied upon by the Commission was partially invalid and should be updated to provide accurate information so that potential impacts to groundwater and public trust resources can be adequately evaluated.
Upon learning of the issues with the Applicant’s WAA, County Counsel’s office immediately reached out to counsel for the Appellant and Applicant informing the parties of the Applicant’s invalid WAA. The parties were further informed that staff would be requesting that the Board remand the Project to the Planning Commission for an advisory recommendation on the topic of groundwater and an updated WAA prior to the Appeal hearing.
On the June 24, 2025, at the appeal hearing the Board remanded the Project to the Commission for preparation of an advisory recommendation on the groundwater use, updated WAA, and any potential impacts resulting from the Project to ensure that the Board of Supervisors (“Supervisors”) has the most accurate and complete information from which to evaluate the Appeal and the Project.
The revised WAA, titled Water Availability Analysis for Castello Di Amorosa dated November 2025, prepared by Bartelt Engineering (2025 WAA) was reviewed by PBES staff and peer reviewed by the County’s consulting hydrological engineering firm Luhdorff & Scalmanini Consulting Engineers (LSCE). The 2025 WAA was found to be technically adequate and LSCE provided recommendations for construction and operational parameters of the wells on site. More importantly, the additional information contained in the 2025 WAA enabled staff to determine baseline groundwater extraction totals from Well #1 and Well #2 in 2019.
Staff is recommending multiple revised conditions of approval related to groundwater use, monitoring, and reporting, including additional limitations on groundwater use, and increased monitoring and reporting obligations beyond the previously approved requirements. Staff is not recommending any changes to the project scope approved by the Commission, and the CEQA determination that the project is Categorically Exempt from CEQA remains the same. Today’s request is for the Commission to review groundwater related matters and forward an advisory recommendation to the Supervisors. The Supervisors will consider this recommendation in their deliberation of the Appeal.
ENVIRONMENTAL IMPACT
ENVIRONMENTAL DETERMINATION: Consideration of a revised Categorical Exemption Memorandum, determining that the project is categorically exempt from the California Environmental Quality Act (CEQA). It has been determined that this type of project does not have a significant effect on the environment and is exempt from CEQA. The project will not impact an environmental resource of hazardous or critical concern, has no cumulative impact, there is no reasonable possibility that the activity may have a significant effect on the environment due to unusual circumstances, will not result in damage to scenic resources, is not located on a list of hazardous waste sites, or cause substantial adverse change in the significance of a historical resource. As proposed the project meets the criteria for eligibility as Categorically Exempt from CEQA under Classes 1, 2, 3, 4, and 11. [See Class 1 (“Existing Facilities”), Class 2 (“Replacement or Reconstruction”), Class 3 (“New Construction or Conversion of Small Structures”), Class 4 (“Minor Alterations to Land”), and Class 11 (“Accessory Structures”) which may be found in the guidelines for the implementation of the CEQA at Title 14 CCR §15301, §15302, §15303, §15304, and §15311]. The project site is not included on a list of hazardous materials sites compiled pursuant to Government Code Section 65962.5.
BACKGROUND AND DISCUSSION
Parcels: The legal parcel on which the Castello di Amorosa winery is located consists of two (2) parcels that have been Separated for Assessment Purposes (SFAP). The Napa County Assessor assigns "SFAP" to parcels with distinct Assessor Parcel Number (APN) for tax assessment purposes when the legal ownership is the same.
Owner: Dario Sattui, 3999 North St. Helena Highway, (707) 967-6260 or Dario@castellodiamorosa.com
Project Agent: Georg Salzner, (707) 967-6261, georg@castellodiamorosa.com
Applicant Representative: Scott Greenwood-Meinert, (415) 772-5741, sgreenwood-meinert@coblentzlaw.com
Zoning District: AW (Agricultural Watershed)
General Plan Land Use Designation: Agriculture, Watershed and Open Space (AWOS)
Project Background: This staff report presents an updated discussion of staff’s evaluation of groundwater use and process for determining the water use baseline. The report presents an updated CEQA Memorandum and Revised Recommended Conditions of Approval. Staff is recommending multiple revised conditions of approval related to groundwater use, monitoring, and reporting. Staff does not recommend changes to the project scope approved by the Commission, and the CEQA determination that the project is Categorically Exempt from CEQA remains the same. Upon consideration of these revised documents the Commission will forward an advisory recommendation to the Supervisors.
Planning Commission Hearing and Project Approval
On April 2, 2025, the Commission approved the Castello Di Amorosa Winery Use Permit Major Modification No. P19-00459, to recognize and approve items that are out of compliance with the permitted entitlements and for an expansion beyond existing entitlements. The Commission further found the project categorically exempt from the CEQA under Classes 1, 2, 3, 4, and 11. Link to Planning Commission April 2, 2025, hearing staff report and attachments, including Attachment “F” Water Availability Analysis August 2024. <https://napa.legistar.com/LegislationDetail.aspx?ID=7270666&GUID=DA8FEEC8-E376-4F81-B8E8-69D657D6CCCE>
Use Permit History - Use Permit No. U-278485 was approved by the Planning Commission on January 6, 1988, permitting a 250,000 gallon per year winery with public tours and tastings. Numerous use permit modifications were approved between 1989 and 2015. The original entitlements associated with the Major Modification request are listed below.
-Employees-
25 employees during crush and 15 employees during non-crush.
-Hospitality areas-
2,678 s.f. Public tasting room
-Visitation- Public Tastings - Pre-WDO entitlement-
Summer Weekdays (April 1-Dec 2nd) - A maximum of 50 persons per day
Summer Weekends (April 1-Dec 2nd) - A maximum of 200 persons per day
Winter Weekdays (Dec 2 to April 1) - A maximum of 25 persons per day
Winter Weekends (Dec 2 to April 1) - A maximum of 75 persons per day
-Marketing-
Use Permit Modification #94077 Condition of Approval No. 8. Approved by staff on March 22, 1995. A Marketing Plan consisting of:
a. Retail sales conducted in the tasting and sales room from 9-6:00 pm from March through October and from 9-5:00 pm from November through February.
b. Public tours and tastings from 9-6:00 pm from March through October and 9-5:00 pm from November through February. Tours and tastings may be offered at any event at the winery.
c. Promotional events for up to 300 people in the courtyard, hall and grounds, with or without sit down lunches and/or dinners or buffets.
d. Cooking classes and educational seminars conducted as needed to promote the winery and its products.
e. Gift shop: Sales of wine related gift items winery souvenirs and promotional items will be sold in the tasting room.
f. Marketing off-site including sending a newsletter with offers of wine and related products for sale.
i. Newsletter: A newsletter will be sent monthly or less frequently as needed with offers of wine and related products for sale, soliciting the availability of the winery for events.
ii. Wine of the Month Club: A wine of the month club will be instituted sending wine to customers’ homes or businesses periodically.
iii. Competitive Tastings: the winery’s products will be entered in local, regional, national and international tasting events.
iv. Promotional Tastings: The winery will attend various charitable functions, fairs, and similar events to pour wine or donate wine for such purposes.
v. Advertising: The winery will advertise, locally, regionally, nationally and internationally, its wines, its winery, and its public tours and tastings.
Use Permit Major Modification Approval - The Commission’s April 2, 2025, approval included recognition of an increase in the number of employees to 153 employees; an increase in daily visitation to 427,541 annual guests (including daily and weekly maximums); an increase in annual marketing events a total of 103 events; and allowing hospitality activities in portions of the building originally approved for production uses (approximately 18,550 s.f. located in numerous rooms throughout the winery buildings). The Project approval also included new requests for designation of additional areas within the buildings for hospitality uses (approximately 14,000 s.f. converted from entitled production areas); conversion of a portion of the existing Type 1 cave (approximately 8,823 s.f.) to a Type 2 cave, allowing tours; increase the number of parking spaces in two (2) areas by 38 spaces for a total of 177 spaces; and installation of a replacement well, serving as the new Project Well to be used for the existing public water system.
The Commission’s action approved the project as recommended by staff, with three (3) revised conditions of approval and added one new condition regarding groundwater use. Condition of approval (COA) Nos. 1.1.d and 4.20.a. were revised to clarify components of the scope. Based on Commission discussion at the hearing, staff revised COA No. 4.20.g to extend the monitoring requirement for a biannual submittal of visitation and marketing data from three (3) to six (6) years, added the requirement to come before the PC at year three (3) and year (6), and included the requirement for the Fire Marshal or Building Division to perform periodic compliance inspections at least once a year.
The new condition of approval was added by the Planning Commission to ensure that existing groundwater levels and the pump rate for Well #2 are maintained at baseline conditions. To finalize this condition, the Applicant was directed to provide historic water usage data in order to determine a baseline. Approximately three weeks after the Commission hearing and decision on the Project, while the Appeal was pending (see Appeal section below), the Applicant provided the required monthly water usage for 2024 and for part of 2025 for the two wells and the reservoir on the property. Upon review of this data, staff discovered discrepancies between the information provided and what was disclosed in the Applicant’s WAA that was considered by the Commission (“2024 WAA”). Specifically, the Applicant’s data revealed that groundwater pumped from Well #2 greatly exceeded the total groundwater use disclosed in the 2024 WAA by almost double in year 2024 and the total groundwater use from both wells was close to the annual rate of recharge for the property as calculated in the 2024 WAA. This data further revealed additional significant discrepancies relied upon by the Commission, lacked critical information and needed to be updated to provide accurate information so that potential impacts to groundwater, interconnected surface waters, and public trust resources can be adequately evaluated.
Project Appeal and Board of Supervisors Hearing
On April 16, 2025, a timely notice of intent to appeal the Commission’s decision on the project was filed by Water Audit California (WAC) and a timely appeal packet was submitted on April 30, 2025 (the Appeal). At the June 24, 2025, Board of Supervisors (Supervisors) hearing regarding the appeal of the Commission’s decision, the Supervisors granted staff’s request that the Supervisors remand the Project to the Commission for an advisory report on the topic of groundwater prior to proceeding with the Appeal hearing. Link to the Supervisor’s June 24, 2025, staff report and attachments. <https://napa.legistar.com/LegislationDetail.aspx?ID=7435676&GUID=EAE29D2E-D6EA-44FC-83FB-2463416B5560>
Revised Water Availability Analysis
The Applicant submitted a revised Project WAA titled Water Availability Analysis for Castello Di Amorosa dated November 2025, prepared by Bartelt Engineering (Attachment D). The revised WAA (“2025 WAA”) was reviewed by PBES Engineering staff and peer reviewed by Luhdorff & Scalmanini Consulting Engineers (LSCE). The peer review found that 2025 WAA to be technically adequate and included recommendations for construction and operational parameters to be placed on the wells. The recommended parameters have been considered by staff and incorporated into the Revised Recommended Conditions of Approval (see COA Nos. 4.18.a; 4.20.i-m; 6.1.a; 6.15.b; 6.15.f; 6.15.g).
The 2025 WAA included a Tier 1, Tier 2, and Tier 3 analysis. Each tier is discussed separately below, but in summary:
• The Tier 1 groundwater use calculations were updated based on additional water use records. The revised WAA provides water use records supporting the additional water usage of Well #2, due to a more detailed consideration of landscape irrigation and the use of Well #2 for vineyard irrigation (see appendices to the 2025 WAA).
• There was no change to the recharge analysis originally prepared in August 2024. Despite the increase in estimated overall water use, the groundwater extraction level remains under the estimated annual rate of recharge. There were no changes to the Tier 2 analysis that determined there are no springs in the project vicinity and no neighboring, non-project wells located within 500 feet of the project wells.
• The Tier 3 equivalent analysis has been updated to include discussion of Well #2, and operational conditions have been recommended to reduce potential impacts to public trust resources based on existing conditions. There was no change to the analysis of the proposed replacement well, however additional conditions are recommended to further regulate water usage operations to reduce impacts compared to baseline conditions.
Project Analysis - Baseline Conditions
This application was submitted to participate in the County’s Code Compliance Program (Compliance Program) as described in Resolution No. 2018-164 adopted by the Board on December 4, 2018. With submittal of the Major Modification under the Compliance Program, the winery’s existing, unpermitted operations occurring in 2018 - 2019 were used as the operational baseline for the request for recognition and the environmental baseline for the CEQA analysis consistent with the CEQA Guidelines, caselaw, and the Compliance Program.
The original 2024 WAA calculated water use based on existing 2018-2019 operational levels, utilizing standard estimates from the County’s Water Availability Analysis - Guidance Document Adopted May 12, 2015 (“Guidelines”), and the results were assumed to be an accurate representation of water use associated with operations during that time, and since the request was only for recognition of operational uses there was no anticipation that water use would change. Bartelt Engineering, the project engineer, stated in the 2025 WAA that the 2023-2024 data submitted to finalize the new condition of approval was not consistent with the 2016-2019 water use data collected by their firm and used to prepare the Tier 1 analysis in the 2024 WAA. The report states that water use data from the years 2020-2023 was not continuously compiled and added to the 2024 WAA because there were no changes on the property in terms of vineyard size, hospitality levels, production levels, or landscaping projects that would have changed the water demand.
For preparation of the updated 2025 WAA the Applicant compiled water use records from 2018-2024 for Well #1 and #2, water use reported to the SWRCB for the public water system, diversion levels reported to the SWRCB for the on-site reservoir, vineyard irrigation estimates from the winery, and residential landscape irrigation records (See 2025 WAA Appendices C, D, F, G, and I). Regardless of the variations in water use records between the 2024 and 2025 WAAs, staff utilized the detailed records for the 2018-2019 data to establish the baseline, an average of the 2018 and 2019 records. This baseline was used in this analysis and the Revised Recommended Conditions of Approval.
Water sources
Two groundwater wells are used to supply the potable water and irrigation needs of the property. The groundwater wells and subsequent water storage and supply systems are regulated as a Non-Transient Non-Community (NTNC) water system by Napa County Environmental Health under permit #2800043.
Existing Well #1 (Well #1 is the current Project well). The well was constructed in 1987 under Napa County permit 18894. It is located immediately adjacent to the winery building and approximately 55 feet from Nash Creek. The existing pumping rate is 50 gallons per minute. Groundwater from the well is pumped into a two compartment, 35,000-gallon storage tank on the hillside above the winery. The upper compartment has a 19,000-gallon capacity and is dedicated to potable use. The lower compartment has a 16,000-gallon capacity and is dedicated to fire protection. Based on the records provided, the average annual groundwater use from Well #1 for 2018-2019 was 12.4 AFY. Existing Well #1 will be demolished upon successful completion and start-up of the Replacement Well, which is described further below.
Well #2 This well was constructed in 2004 under Napa County permit 96-12662. Well #2 is located approximately 150 feet southeast of Well #1 and approximately 100 feet from Nash Creek. Well #2 is used for landscape irrigation, fire suppression, and vineyard irrigation. It is also an approved backup source for the public water system and was used as such beginning in January 2023 according to the 2025 WAA. Groundwater from Well #2 is primarily pumped into the adjacent 83,000 gallon above ground cistern that supplies the irrigation systems. The Well #2 pump system is also connected to the pipe that fills the 35,000-gallon tank. The Applicant does not have a sub-meter installed to track Well #2’s output to the public water system separately from the overall groundwater produced by Well #2. Based on the records provided, the average annual groundwater use for Well #2 for 2018-2019 was 25 AFY. As discussed below, it is difficult to discern the quantity of the water that was being utilized by the winery (if any) and what was used for vineyard irrigation or other non-winery uses.
Reservoir - On March 9, 1992, The State of California Water Resources Control Board (SWRCB) issued permit #20603 authorizing the collection of up to 20 acre-feet/year in the already existing reservoir on Nash Creek for use as vineyard irrigation. The permit authorized additional diversion, however, the associated reservoir was never constructed. The Applicant conveys irrigation water from the reservoir through a piping system to a booster pump and pressure tank system at the headworks of the vineyard irrigation system. Based on the records provided by the Applicant, 3.9 AF was used in 2018, and 9.1 AF was used in 2019.
Proposed Replacement Well (Replacement Well will replace Existing Well #1 Project Well). Bartelt Engineering, the project engineer, in coordination with the Applicant, identified a general area of the property suitable to install the replacement project well. A Well Location Exhibit is included in the 2025 WAA, showing the potential replacement locations highlighted in purple. The exact location of the replacement project well has not been determined at this time due to unknown factors related to the suitability of subsurface conditions in the potential drilling locations. Rather than propose a singular location, an approximately 3.5-acre area in the northwestern corner of the property has been considered. This area includes a portion of an approximately 11.5-acre vineyard and an area directly adjacent to an existing solar panel array covering approximately one (1) acre. The drilling would occur in a previously developed area, and no tree removal would occur as part of the project.
The 2025 WAA contains construction and operational parameters for the proposed replacement well. LSCE’s peer review of the WAA included recommendations for both construction and operational parameters for the proposed replacement well. These recommendations have been incorporated into the Revised Recommended Conditions of Approval (see COA Nos. 4.20.j; 4.20.k; 4.20.l; 4.20.m; and 6.15.b). The parameters include but are not limited to the location of the proposed well to Nash Creek (no closer than 130 feet and no further than 700 feet), a surface seal depth (a minimum of 150 feet), and a reduced pumping rate of no more than 40 gallons per minute (where no limitation currently exists). Per COA No. 6.15.a. within 30 days of the effective approval date of this modification, the Permittee shall submit an updated well drilling application for the Replacement Well to the Environmental Health Division including the information required by COA No. 6.15.b.
New Statement of Water Diversion and Use Rights. On July 31, 2025, the Applicant filed an Initial Statement of Water Diversion and Use Rights (SWDU) with the SWRCB for a claim of riparian rights to upstream spring water flows in Nash Creek that enter the reservoir. A riparian water right is surface water property right that runs with the land and allows a landowner to take water from a natural watercourse that is contiguous to its property. The property owner has the right to use the water from the adjacent watercourse on the adjacent riparian land for reasonable and beneficial use. This type of water right does not require a permit or advance approval from the SWRCB. However, the use is required to be reported to the SWRCB by filing a Statement of Water Diversion and Use the year after the water has been used. Nash Creek flows directly through the Applicant’s property and therefore the Applicant has a corresponding riparian water right to use water flowing from the creek. The separate approved reservoir permit authorizes 20 AF of water to be collected and stored from November 15 to March 1. Nash Creek is spring-fed and can flow year-round, so water continues to flow from Nash Creek after March 1, and enters the pond outside the permitted winter storage season. The Applicant filed SWDU S029337 because water flowing in Nash Creek is used for irrigation of riparian lands during the summer months. When water is diverted and used from Nash Creek after March 1, it is a riparian direct diversion. The filing is for a direct diversion of surface water of 12 gallons per minute to be used for irrigation. This quantity is additive to the 20 AF of surface water allowed for vineyard irrigation under the reservoir permit. The Initial Statement of Water Diversion and Use allows the claimant to use the water when it is available and does not quantify an annual use limit.
Revised Water Availability Analysis
Tier 1 - Groundwater Demand and Annual Rate of Recharge Analysis
Both WAAs provide calculations for residential, winery, and agricultural water uses. The following summarizes the use calculations in the 2024 WAA and 2025 WAA and denotes differences in estimates. Summary notes have been added to explain the changes, with further narrative included below. The WAAs contain further details on water usage assumptions and calculations for each use category.
Total Groundwater Use
Includes: Winery, Residential, and Agricultural
2024 WAA: 15.99 AF
2025 WAA: 34.34 AF
Difference: +18.35 AF
Note: The primary change is due to the incorporation of landscape irrigation records and detailed estimates not included in the 2024 WAA.
Winery
Includes: Process, Winery Landscaping, Employees, Tours and Tastings, and Marketing Events
2024 WAA: 14.22 AF
2025 WAA: 24.47 AF
Difference: +10.25 AF
Note: The primary change is due to the addition of an estimate of landscaping irrigation.
Residential
Includes: Primary Residence, Second Unit, Guest Cottage, and Residential Landscaping
2024 WAA: 1.6 AF
2025 WAA: 9.7 AF
Difference: +8.1 AF
Note: The primary change is due to the addition of recorded landscape irrigation data.
Agricultural
Includes: Vineyard Irrigation and Farm Management
2024 WAA: 0.17 AF
2025 WAA: 0.17 AF
Difference: No change
Note: The 2025 WAA still assumes that vineyard irrigation will primarily be provided by the reservoir, however, it is noted that groundwater could be used as a back-up source as needed.
The following discusses the changes in the estimates of landscape irrigation since those represent the largest water use change. The 2024 WAA calculated water use based on existing 2018-2019 operational levels, utilizing standard estimates from the County’s WAA Guidelines. The Guidelines calculation for residential use includes an allocation for “minor to moderate landscaping” with a range from 0.5 - 0.75 AF for a primary residence and 0.2 - 0.5 AF for a second residence. The Guidelines calculation for winery use includes an allocation for landscaping based on production quantity - 0.5 AF per 100,000 gallons of wine. In preparation for the revised 2025 WAA, the project engineer was able to obtain metered records for the residential landscaping. The 2025 WAA identified the averages residential landscape irrigation at 8 AFY based on metered values between the years 2018 and 2024, which ranged from 6.6 AF to 9.4 AF (See 2025 WAA Appendix F). The 8 AF is considerably greater than the standard calculation of 0.75 AFY in the 2024 WAA, which was based on assumed volumes in the County’s Guidelines.
Currently, there are no water meters installed to track the non-residential landscape irrigation water use on the property; therefore, the winery does not have records for the winery landscape irrigation. The method utilized by Bartelt Engineering in the 2025 WAA to generate an estimate was subtracting known or calculated values from the overall water use recorded by the well and surface water reservoir meters. Bartelt Engineering concluded that based on the available information, non-residential landscaping irrigation use has ranged from approximately 8.5 AFY to as high as 36.5 AFY. The 2025 WAA recognized that the estimated groundwater recharge potential of 40.5 AFY does not support irrigation demands at the higher end of the historical range, so the applicant selected 12 AFY as the projected landscape irrigation demand moving forward. However, the historical irrigation estimates cannot be attributed solely to landscape irrigation because Well #2 served as the primary source of vineyard irrigation between 2013 and 2024. As a result, the historical values reflect a combination of landscape and vineyard irrigation demands and are not an appropriate basis for estimating future landscape water use.
To ascertain estimated non-residential landscape irrigation volumes from Well #2, staff conducted an independent evaluation of the landscaped areas associated with each parcel. This evaluation included a site visit on February 11, 2026, with the applicant's representative, engineer, and facilities manager to identify actively irrigated landscape areas. Using GIS mapping of the areas identified during the site visit, staff calculated approximately 99,863 square feet of irrigated landscaping and approximately 60 Italian cypress trees on the winery parcel. Applying the factor provided in the 2015 WAA Guidelines of 0.1 AFY per 2,000 square feet of non-xeriscape landscaping, the estimated landscape irrigation demand for the winery parcel is approximately 5 AFY. This independently derived estimate supports the conclusion that the projected landscape irrigation demand is substantially lower than the higher historical estimates containing in the 2025 WAA, which included vineyard irrigation demands.
Based on the independent landscape irrigation analysis, along with the applicant’s commitment in the 2025 WAA that the on-site reservoir will serve as the primary source of vineyard irrigation moving forward, and the County’s obligation to ensure that groundwater extraction does not increase beyond historically established levels, staff recommends recognizing the non-residential landscape irrigation allocation at 5 AFY, which effectively reduces the 12 AFY estimated in the 2025 WAA by 7 AFY. This adjustment would therefore result in a reduction of the property’s maximum allowable groundwater estimate and associated cap on annual extraction for Well #2 from 34.34 AFY to 27.34 AFY. This recommended cap is consistent with the applicant’s stated operational commitment and together with the required Water Demand Management Plan, which includes water metering and reporting by use category, will provide an ongoing mechanism to evaluate irrigation practices, track water consumption, and promote the efficient use of groundwater resources through adaptive management and water conservation measures.
As noted above, there were no changes to the Groundwater Recharge Analysis, dated August 10, 2024, prepared by Richard C. Slade & Associates LLC (RCS) consulting groundwater geologists. The total annual average groundwater recharge at the subject property was calculated at 40.5 AFY. This included a combination of a recharge estimate for the portion of the site within the Napa Valley Subbasin and portion outside the Subbasin. The RCS analysis was reviewed by LSCE as part of the revised 2025 WAA. LSCE calculated a recharge value considering the entire site outside the Subbasin, noting that the RCS recharge was calculated using a pre-2018 Subbasin boundary that shows part of the property within the Napa Valley Subbasin. The LSCE recharge estimate of 44 AFY exceeds the value cited in the RCS analysis. The estimated total water demand on this parcel, 34.34 AFY, is less than the estimated groundwater recharge volume, and the Tier 1 Water Criterion is met.
Tier 2 Well and Spring Interference
No changes were made to the Tier 2 analysis. Based on information obtained through Napa County public records, there are no springs in the project vicinity and no neighboring wells located within 500 feet of the Proposed Replacement Well. Existing Well #2 is located approximately 150 feet from Existing Well #1. As described in the Tier 3 Analysis below, Well #1 will be replaced in a location greater than 500 feet from Well #2. Therefore, the Tier 2 well interference criterion is presumptively met.
Tier 3 Equivalent Analysis
As required by Napa County’s May 12, 2015, WAA Guidance Document and the Interim Napa County Well
Permit Standards and WAA Requirements - January 2024, the project must examine the horizontal distance
between wells utilized by the project and Significant Streams, as determined by the Napa County Well Permit Standards. The proposed Replacement Well location and existing Well #2 are within 1,500 feet of a Significant Stream, Nash Creek, therefore, the Applicant must prepare a Tier 3, or equivalent analysis, to demonstrate that a hydraulic separation between the wells and Nash Creek is provided by geologic conditions at the site or assume connectivity and propose modifications to the wells or operation of the wells to reduce impacts.
There was no change to the analysis of the proposed Replacement Well, however additional construction and operational conditions are recommended to further regulate water use operations. In summary, staff’s revised condition recommends a deeper seal depth than what was included in the conditions of approval approved by the Commission, and a new condition is being proposed to limit the total annual groundwater extraction, based on the 2018-2019 operations (see COA Nos. 4.20.j.-k).
The revised 2025 WAA discusses the existing location and operational components of Well #2 and proposes new conditions on operations in order to maintain 2018-2019 baseline conditions and further reduce potential harm (if any). In summary, a new condition recommends a limit on annual extraction based on 2018-2019 operations and reduces the pumping rate below the current maximum rate.
The construction and operational parameters for the proposed replacement well and Well #2, as described above, will reduce impacts (if any) based on existing conditions and satisfy the WAA Tier 3 equivalent analysis criteria.
Public Trust
Public Trust - The public trust doctrine (Doctrine) requires the state and its legal subdivisions to “consider,” give “due regard,” and “take the public trust into account” when considering actions that may adversely affect a navigable waterway. (Environmental Law Foundation v. State Water Resources Control Bd.; San Francisco Baykeeper, Inc. v. State Lands Com.) There is no “procedural matrix” governing how an agency should consider public trust uses. (Citizens for East Shore Parks v. State Lands Com.) Rather, the level of analysis “begins and ends with whether the challenged activity harms a navigable waterway and thereby violates the public trust.” (Environmental Law Foundation, 26 Cal.App.5th at p. 403.). As demonstrated in the Environmental Law Foundation vs State Water Resources Control Board Third District Appellate Court Case, that arose in the context of a lawsuit over Siskiyou County’s obligation in administering groundwater well permits and management program with respect to Scott River, a navigable waterway (considered a public trust resource), the court affirmed that the public trust doctrine is relevant to extractions of groundwater that adversely impact a navigable waterway and that Counties are obligated to consider the doctrine, irrespective of the enactment of the Sustainable Groundwater Management Act (SGMA).
On January 10, 2024, Napa County released a Tier III Water Availability Analysis guidance memorandum, providing guidance for complying with Public Trust. A Tier III review or equivalent analysis is the County’s adopted method for complying with its duties under the Doctrine. The WAA includes a Tier III equivalent analysis. Additionally, COA Nos. 4.20.i, j, k, and l, are recommended to impose groundwater use limitations and metering on both wells, monitoring and reporting of groundwater use (reporting at the County’s request), and includes the County’s ability to recommend additional measures or revoke the use permit in the future if substantial evidence exists that the Project substantially affects the groundwater basin. These project components and conditions of approval provide even greater protection, further reduce any alleged harm, and align with the requirements of the January 10, 2024, Public Trust Doctrine Memorandum. The County has satisfied its duty.
Conditions of Approval
The four (4) conditions modified at the April 2, 2025, Commission hearing note that the language was “Revised April 2, 2025, Planning Commission Hearing”. The proposed Revised Recommended Conditions of Approval (Attachment A) includes track changes - underline and strikethrough - denoting the proposed changes from the Conditions of Approval approved at the prior Commission hearing. The proposed revised conditions are specific to groundwater use and have been updated based on staff analysis and LSCE’s recommendations. There are no recommended changes to the scope of the project. The new and revised conditions are discussed below.
COA Nos. 4.18.a. and 6.1.a. The Engineering Division memorandum has been updated to incorporate the recommendations provided by LSCE.
COA Nos. 4.18. b. and 6.1.b. The Environmental Health Division memorandum has been updated to remove the construction parameters identified in the 2024 WAA, because the Engineering Division memorandum includes updated construction parameters.
COA No. 6.15.b. Updated to clarify the well permit is for the Replacement Well.
COA No. 4.20.d. This condition has been removed as an individual condition. The same pump rate restriction has been incorporated into COA 4.20.j. for clarity on operational restrictions.
COA No. 4.9. Groundwater Management. This standard condition of approval has been Reserved, and the requirements to record groundwater use and report to the County will be replaced by the following project specific conditions related to groundwater management.
COA No. 4.20.i. Groundwater Management. Requires submittal of a Groundwater Demand Management Program.
COA No. 4.20.j. Replacement Well. Places an annual extraction limit on Replacement Well and carries forward the maximum pump rate restriction previously included in COA 4.20.d.
1. Limited to annual extraction volume of 12.4 acre-feet (AF).
2. Equipped with a flow restrictor, pump, or similar equipment that limits pumping rate to 40 gallons per minute (gpm) or less.
Note: 12.4 AF is the average of the 2018-2019 water use data.
COA No. 4.20.k. Well #2. Places an annual extraction limit on Well #2 and includes a maximum pump rate restriction.
1. Limited to annual extraction volume of 15 acre-feet (AF).
2. Equipped with a flow restrictor, pump, or similar equipment that limits pumping rate to 70 gallons per minute (gpm) or less.
Note: The 2025 WAA estimates annual total groundwater use of 34.34 AFY. Staff recommends reducing this volume by 7 AF, a decrease in the non-residential irrigation allocation estimate, resulting in a total of 27.34 AFY. Taking this annual total and subtracting the Replacement Well extraction limit of 12.4 AF results in approximately 15 AF.
COA No. 4.20.l. Requires installation of water metering infrastructure on Wells #1 and #2. The infrastructure shall be capable of accurately measuring and recording all groundwater extracted and used on the project site, including but not limited to residential, landscaping, agricultural, winery, hospitality, and all other operational uses on the parcels.
COA No. 4.20.m. Requires information on pump flow restrictor equipment to be submitted to the PBES Director.
COA No. 6.15.b. Revised to reference the 2025 WAA and incorporate LSCE’s recommendations on surface seal depth. Due to the change in seal depth requirements, previous construction and perforation depth minimums are not required.
COA No. 6.15.f. Groundwater Demand Management Program. Requires submittal of a Groundwater Demand Management Plan and includes specific requirements to be included in the Plan. Requirements include a detailed schematic and narrative description of the water infrastructure equipment and metering devices, and an explanation of how the data will be collected to provide a clear breakdown of each water use by category. Reporting shall also include data for non-groundwater sources on-site, including the on-site reservoir and any water use authorized pursuant to existing or future surface water rights, licenses, registrations, permits, or claims. This condition contains timelines for data reporting.
COA No. 6.15.g. Requires submittal of information on pump flow restrictor equipment for PBES Director approval and includes timing on installation of equipment.
Discussion of Identified Water Use Discrepancies
As discussed above, submittal of the 2024-2025 data raised several questions regarding the actual water use on the property. The 2025 WAA included water use records for 2018-2025, which showed a significant fluctuation in water use throughout that time period. The 2025 WAA considers the discrepancies and provides possible reasons for the fluctuations in usage and discusses data collection inconsistencies and reporting errors.
It is worth noting that while WAA water use calculations are broken down by category, these are estimates, and fluctuations in annual usage are natural. For example, a winery may utilize more water for production due to a high growth year, less water use resulting from reduced visitation (pandemic), not hold any marketing events, or a residence may be vacant for a time. This results in the potential for water use to vary
by category. Additionally, project approval generally does not limit how much water can be used per category but instead imposes a cap on total groundwater.
Despite the issues identified below, staff concluded the provided data was sufficient to define water use from 2018-2019, the baseline levels utilized for analysis and generation of conditions of approval.
The following briefly summarizes the primary issues regarding groundwater use.
1. Groundwater use exceeded the estimated use and recharge potential identified in the 2024 WAA.
Records provided by the Applicant in the 2025 WAA show that historic water use greatly exceeded the estimate of 15.99 AFY provided in the 2024 WAA, specifically from 2020-2023 where it ranged from 52 AFY-67 AFY. Not only was the usage significantly higher, in some years it exceeded the estimated recharge rate of 44 AFY. The Applicant believes that excessive landscape irrigation at the winery is what caused the groundwater use spikes, noting that non-residential irrigation is not currently metered. Additionally, the Applicant acknowledges that they were using groundwater to irrigate the vineyard, whereas the 2024 WAA said vineyard irrigation was provided by the reservoir.
The winery does not currently have a limit on groundwater use, and until preparation of the 2024 WAA, the annual estimated recharge rate was not contained in the project documents on file with the County. Prior use permit modifications did not include increases in winery operations that would have required review of groundwater use. The project was submitted as part of the Code Compliance Program due to unpermitted increases in levels of operations.
Although a maximum allowable groundwater use has not been imposed, the Applicant has been tracking water use with Meter.Me, a water monitoring service, beginning in 2023. This is partially the reason groundwater use was reduced by approximately 12 AF in 2023, 15 AF in 2024, and 20 AF in 2025. The most recent data shows that groundwater use continues to be reduced through conservation measures and increased use of the surface water reservoir (Attachment G).
Recent decrease in Total Groundwater Use - Well #1 and Well #2
2022 - 67.3 AF
2023 - 55 AF
2024 - 39.2 AF
2025 - 19.2 AF
2026 (Jan-May) - 3.5
2. Limited use of reservoir and increased use of Well #2.
The 2024 WAA did not include vineyard irrigation in the groundwater demand calculation, because the existing reservoir on site was presented as the primary source of water for vineyard irrigation. The permit allows diversion and use of up to 20 AFY for vineyard irrigation, which is expected to be sufficient to supply the estimated need for vineyard irrigation. Currently, there is not a meter system that tracks the overall water use in the vineyard, so vineyard irrigation estimates are based on irrigation schedules, the number of vines irrigated, and details regarding the emitters associated with each vine. Records submitted to the State show that use of the reservoir during 2018-2023, ranged from 3.4 AFY to 9.1 AFY, while vineyard irrigation estimates during this time ranged from 9.2 AFY to 17.9 AFY. The 2025 WAA states that Well #2 was the primary source for vineyard irrigation between 2013 and 2024, not a back-up source as stated in the 2024 WAA. Due to the limited use of the reservoir, the use of groundwater for vineyard irrigation caused the records to greatly exceed the 2024 WAA estimate.
3. Inconsistent data reported to the State.
The SWRCB requires annual reporting for water diversion from the reservoir and the overall water volume used by the public water system. The 2025 WAA notes that data for each system and permit are uploaded to separate SWRCB-run databases by different members of Castello di Amorosa’s staff and/or contracted employees. In the days leading up to the April 2, 2025, Planning Commission hearing, a public comment noted discrepancies with the Castello di Amorosa’s reservoir water use reporting to the SWRCB. The reservoir reporting was promptly amended to address the public comment and resubmitted to the SWRCB in April 2025.
Reporting to the SWRCB for the public water system is only required to include data related to potable water use. Based on the SWRCB database reporting, Well #1 was the sole supplier of water for the public water system from 2018-2022. In January 2023, when groundwater from Well #2 was needed due to issues with Well #1, State reporting criteria required that water use data from Well #2 be included. The Applicant does not have a sub-meter installed to track Well #2’s output to the public water system separately from the overall groundwater produced by Well #2. Therefore, Castello di Amorosa staff revised the submittals to include the full Well #2 meter readings. When reading the annual public water system reported water use on the SWRCB database, it shows a drastic increase in potable water use from 2022 to 2023. However, the water use value reported in 2023 included the vineyard and landscape irrigation water use that were also supplied by Well #2; and is therefore not a clear representation of potable water use.
In July 2025 a representative from the SWRCB contacted the Applicant’s staff in charge of reporting to the SWRCB and informed them that they had received an anonymous complaint alleging diversions were being made outside the season allowed under the reservoir permit. After review, it was determined that further corrections to the annual reporting forms were required to fix irrigation water use values that were incorrectly placed in the “diversions” column of the reporting form. The SWRCB investigated the complaint and on December 12, 2025, the SWRCB issued a letter to the Applicant that the investigation was complete, and it had been determined that they were not in violation of their permit or riparian statement and no further action was needed (Attachment H).
CEQA Analysis
Staff prepared a revised Categorical Exemption Memorandum, focusing on changes to the prior groundwater analysis. The additional analysis did not change the overall determination that the project is categorically exempt from the CEQA. The project will not impact an environmental resource of hazardous or critical concern, has no cumulative impact, there is no reasonable possibility that the activity may have a significant effect on the environment due to unusual circumstances, will not result in damage to scenic resources, is not located on a list of hazardous waste sites, or cause substantial adverse change in the significance of a historical resource. As proposed the project meets the criteria for eligibility as Categorically Exempt from CEQA under Classes 1, 2, 3, 4, and 11. See Class 1 (“Existing Facilities”), Class 2 (“Replacement or Reconstruction”), Class 3 (“New Construction or Conversion of Small Structures”), Class 4 (“Minor Alterations to Land”), and Class 11 (“Accessory Structures”).
Public Comments
One public comment was received following publication of the public hearing notice on July 2, 2026. Additional public comments received following publication of the staff report will be provided to the Commission.
Decision Making Options
The Board remanded the Project to the Commission for an advisory recommendation to the Board on groundwater related matters including, but not limited to, the updated 2025 Water Availability Analysis, staff’s revised analysis of groundwater use, and the associated CEQA analysis. Consistent with the Board’s direction, staff recommends that the Planning Commission recommend adoption of the revised conditions of approval discussed above, to find the Project Categorically Exempt from CEQA, and to approve Use Permit Modification P19-00459. The Supervisors will consider this recommendation in their deliberation of the Appeal.
Disposition - Staff considered the revised 2025 WAA and incorporated groundwater recommendations into the revised conditions of approval. The project scope did not change and the CEQA determination that the project is Categorically Exempt from CEQA remains the same. Groundwater use will be below the estimated annual rate of recharge, and the staff recommended conditions provide a volumetric cap on groundwater use and pump rates, impose monitoring and reporting, and provide greater protection to groundwater supply and public trust resources. To support the County’s protection of groundwater resources, staff’s recommended cap on groundwater use includes a reduction in the estimated water use (7 AFY attributed to non-residential irrigation). However, the Commission may recommend reject staff’s recommended volume reduction, in whole or in part, as well as impose additional conditions related to groundwater if the Commission finds conditions are necessary to further reduce impacts on groundwater.
Action Required - Follow the proposed action listed in the Executive Summary. If conditions of approval are to be amended or if additional groundwater related conditions are proposed, specify language for new or amended conditions at the time the motion is made.
Attachments
A. Revised Recommended Conditions of Approval and Agency Approval Memos
B. Updated Categorical Exemption Determination
C. Revised Water Availability Analysis November 2025
D. Engineering Division Technical Adequacy Memorandum
E. LSCE Peer Review Memorandum
F. SWRCB Conclusion of Complaint
G. 2025-2026 Water Use Records
H. Graphics - Individual Sheets from Revised WAA
I. Public Comments