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: Piazza del Dotto Winery P18-00143-MOD
RECOMMENDATION
title
YOUNTVILLE VINEYARDS LLC / PIAZZA DEL DOTTO WINERY / USE PERMIT MAJOR MODIFICATION P18-00143
CEQA STATUS: Consideration and possible adoption of a Mitigated Negative Declaration and Mitigation Monitoring Reporting Program (MMRP) (SCH #2025050553). According to the proposed Mitigated Negative Declaration, the proposed project would not have any potentially significant environmental impacts with incorporation of mitigation measures for Biological Resources. This project is not on any lists of hazardous waste sites enumerated under Government Code Section 65962.5.
REQUEST: Approval of a Major Modification to increase production, number of employees, and number of visitors. The project would add additional events to the existing marketing plan, permit on-premises consumption in additional areas on site, and allow outdoor speakers for background music. Physical changes on site include construction of an approximately 45,500 s.f. winery building with a 700 s.f. lounge building, increase the existing, approved cave from 16,000 s.f. to 32,500 s.f., cabanas on the hospitality building patio, and additional parking spaces. The project site is located on a 21.7-acre parcel at 7466 St. Helena Highway/State Route 29, Yountville, CA 94558. The General Plan designation is Agricultural Resource (AR), and the Zoning is Agricultural Preserve (AP). APN 031-120-040. [Formerly APN 031-120-038 (SFAP) and 031-130-032 (SFAP) - Revised per Lot Line Adjustment LLA 2106 (Recorded December 26, 2024), referred to as “LLA 2106 Adjusted Parcel A” in the public hearing notice and Mitigated Negative Declaration].
STAFF RECOMMENDATION: Adopt the Mitigated Negative Declaration/MMRP and approve the Use Permit Major Modification, as conditioned.
STAFF CONTACT: Emily Hedge, Planner III, (707) 259-8226 or emily.hedge@countyofnapa.org
APPLICANT REPRESENTATIVE CONTACT: Bill Dodd, Dodd and Chaaban Strategies LLC.; 707-287-7249; bill@doddchaaban.com
CONTINUED FROM THE JUNE 18, 2025, PLANNING COMMISSION MEETING.
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EXECUTIVE SUMMARY
PROPOSED ACTIONS
That the Planning Commission:
1. Adopt the Mitigated Negative Declaration and the MMRP based on Findings 1-7 in Attachment A; and
2. Approve Use Permit Modification No. P18-00143, based on recommended Findings 8-12 in Attachment A and subject to the recommended Conditions of Approval in Attachment B.
DISCUSSION:
Use Permit History - On October 6, 2010, Use Permit P08-00185 and Variance P09-00492 for Ca’Nani Winery, were approved by the Planning Commission. The winery authorized a 48,000 gallon per year winery with by-appointment visitation and a marketing plan. Site development consisted of a two-story winery building, approximately 16,000 s.f. of caves, parking spaces, an entrance monument and sign, and a new process wastewater septic system. A Variance granted a reduction in the minimum 600-foot winery setback from SR 29/St. Helena Highway to 520 feet. Three minor modifications approved physical changes to the winery, including replacement of an equipment storage building with an approximately 4,000 s.f. hospitality building with a commercial kitchen, installation of an interim approximately 7,000 s.f. uncovered crush pad, reconfigure the parking lot, various site improvements, and adding on-premises consumption within the hospitality building and outdoor patio.
Planning Commission Hearings - Major Modification Application P18-00143 was heard before the Napa County Planning Commission on April 19, 2023, June 7, 2023 (Continuance only), and July 13, 2023. At the July meeting, the Commissioners and members of the public requested additional information and analysis on project components, and the hearing was continued to a date uncertain. The applicant submitted revised application materials on December 1, 2023, and February 20, 2025, modifying the project request to reduce a number of operational components. The project was scheduled to be heard at the June 18, 2025, meeting, however the project was continued to the August 20, 2025, meeting to permit staff time to incorporate clarifying information on the Water Availability Analysis into the staff report and supporting documents. This staff report evaluates the project in its entirety.
The prior staff reports, with attachments, are available for reference, and can be found through the Planning Commission home page - https://www.countyofnapa.org/1449/Planning-Commission
April 19, 2023 - https://napa.legistar.com/LegislationDetail.aspx?ID=6335373&GUID=8F0AFECE-7002-47B7-AC29-5F9C4529D891
June 7, 2023 - https://napa.legistar.com/LegislationDetail.aspx?ID=6335578&GUID=B7965551-46D3-45C1-985B-3EA707A24D2E
July 13, 2023 - https://napa.legistar.com/LegislationDetail.aspx?ID=6335746&GUID=874CD840-CE19-4D61-B2AD-977654DD6005
June 18, 2025 - https://napa.legistar.com/LegislationDetail.aspx?ID=7430704&GUID=90556E5D-1841-4642-B6BC-30FC50BCDCD8
CEQA History - On February 21, 2023, staff submitted an Initial Study/Negative Declaration (SCH #2023020504) to the State Clearing House (SCH) website. On March 9, 2023, staff received comments from the California Department of Fish and Wildlife (CDFW). The comments, on Swainson’s hawk surveys and a Lake and Streambed Alteration (LSA) Notification, were incorporated into the project Recommended Conditions of Approval presented at the July 13, 2023, Planning Commission hearing. Due to the revision in the project description resulting from the 2023 hearings, the Initial Study has been revised to incorporate the modified project description and includes the CDFW’s recommendation for Swainson’s hawk surveys as a mitigation measure. The Initial Study/Mitigated Negative Declaration/MMRP was submitted to the SCH on May 13, 2025, (SCH #2025050553) for a 30-day review. On June 4, 2025, staff received a letter from Caltrans in response to their review of the Mitigated Negative Declaration. The letter expressly states, “this correspondence does not indicate an official position or approval by Caltrans on this project and is for informational purposes only.” The letter has been provided to the applicant and is included in Attachment O - Public Comments. No other comments were received from state agencies as a result of this CEQA review.
Project Proposal - Modify an existing 48,000 gallon per year winery, previously approved under Use Permit P08-00185 and subsequent modifications to allow the following:
a. Increase annual production from 48,000 gallons to 75,000 gallons;
b. Increase employees from 13 full-time employees to 17 full-time employees, no change to existing two (2) part-time employees;
c. Increase tours and tastings by appointment from 40 per day Monday-Thursday and 75 per day Friday-Sunday to 120 per day Monday-Thursday and 130 Friday-Sunday;
d. Revise the annual marketing plan to include an additional six (6) events with a maximum of 120 people per event;
e. On-premise wine consumption in the new winery building hospitality areas, winery building second story outdoor areas, the Grotto courtyard, the hospitality building, and the hospitality building outdoor patio;
f. Construct a new, approximately 10,500 s.f. winery building consisting of production and hospitality space with a separate 700 s.f. lounge building;
g. Construct an approximately 16,500 s.f. cave expansion, creating a total cave size of approximately 32,500 s.f., the Type 3 cave includes a tasting room and commercial kitchen, new cave portal on the northeastern branch of the cave, and allows guided tours;
h. Construct two (2) approximately 200 s.f. cabanas on the patio of the existing hospitality building;
i. Convert hospitality building storage space to office and allow public access and use of the second floor balcony;
j. Allow outdoor speakers in the outdoor tasting areas for playing background music (during visitation hours between 11:00 a.m. and 6 p.m. and daytime marketing events occurring between 11:00 a.m. and 1:00 p.m.);
k. Increase parking spaces from 49 spaces to 54 spaces;
l. Install 10 bicycle parking spaces;
m. Continue use of the existing hold and haul system; and
n. Permit future installation of an onsite process wastewater system.
Staff has reviewed the revised proposal and found it to be consistent with the Zoning Ordinance and applicable General Plan policies. The project has been designed so that there will be a decrease in water use and the use will remain below the estimated groundwater recharge rate. A Transportation Demand Management plan has been proposed to help reduce potential transportation impacts. Staff prepared an Initial Study/Mitigated Negative Declaration/MMRP (SCH ##2025050553) that evaluated the environmental impacts of the project and did not identify any potentially significant effects, with the inclusion of a mitigation measure for biological resources. With no significant environmental effects anticipated, and with the project’s consistency with adopted County policy and regulations, staff believes that the necessary findings for the project can be made. Staff recommends approval of the project, subject to the recommended Conditions of Approval included in Attachment B.
ENVIRONMENTAL IMPACT
ENVIRONMENTAL DETERMINATION: Consideration and possible adoption of a Mitigated Negative Declaration/MMRP (SCH #2025050553). According to the proposed Mitigated Negative Declaration/MMRP, the proposed project would not have any potentially significant environmental impacts with incorporation of mitigation measures for Biological Resources. This project is not on any lists of hazardous waste sites enumerated under Government Code Section 65962.5.
BACKGROUND AND DISCUSSION
PROJECT INFORMATION:
Owner: Dave Del Dotto, Yountville Vineyards LLC; 1291 Zinfandel Lane, Saint Helena, CA 94574; (707) 963-2134; dave@deldottovineyards.com
Representative: Bill Dodd, Dodd and Chaaban Strategies LLC.; 707-287-7249; bill@doddchaaban.com
Architect: Dan Westphal, O’Malley Wilson Westphal, Inc, 555 Fifth Street, Suite 200, Santa Rosa, CA 95401; (707) 636-0828; dan@omalleywilsonwestphal.com
General Plan Land Use Designation: Agricultural Resource (AR)
Zoning District: Agricultural Preserve (AP)
Parcel size: 21.7 acres.
Application Filed: April 23, 2018
Resubmittals Received: October 25, 2018; October 25, 2019; December 21, 2020; September 21, 2021; March 17, 2022; October 12, 2022; November 30, 2022.
Application deemed complete: December 30, 2022
Resubmittals received after the July 13, 2023, Planning Commission hearings: December 1, 2023, February 20, 2025, and July 9, 2025
Courtesy Notice Sent: March 2, 2020
Parcel History:
October 2010 - The Planning Commission approved the original Ca' Nani Winery Use Permit P09-00185-UP and Variance P09-00492-VAR. This approval entitled a new, 48,000 gallon per year winery with a two-story, 16,243 s.f. winery building with 5,800 s.f. of offices, 1,670 s.f. of tasting/sales area; 2,281 s.f. of barrel storage, total 2,410 s.f. roof deck areas and 15,970 s.f. of cave area with four portals for a winery totaling 56,370 s f.; conversion of an existing 1,460 s.f., detached garage to a farm equipment storage building and a new 375 s.f. utility building; 13 fulltime and 2 part-time employees; 44 on-site parking spaces; new entrance monument and sign; up to 75 visitors per day (Fri-Sun) and 40 visitors per day (Mon-Thurs) by appointment only; a marketing plan with 27 events per year with a maximum of 24 people (10 as evening events ending at 10:00 PM), two events per year with a maximum 49 people, one event per year with 100 people, and one event per year with 300 people; and a new process wastewater septic system. A Variance was also granted to reduce the minimum 600-foot winery setback from SR 29/St. Helena Highway to 520 feet.
August 2013 - The PBES Director approved Use Permit Modification No. P13-00054-MOD to allow phased development of the winery, replacement of a 1,460 s.f. equipment storage building with a 2,311 s.f. tasting room building, and installation of an interim 6,908 s.f. uncovered crush pad.
October 2014 - The PBES Director approved Use Permit Modification No. P14-00141-MOD to modify the existing one-story tasting room building to add a 1,680 s.f. second story, relocate the fire tank and fire access road, reconfigure the parking lot, revise the design of the entry gate and structure, replace the existing garden trellis, add a crush pad to the south of the winery pad area, enlarge the mechanical room, and construct a retaining wall for the winery building.
October 2015 - The Planning Commission approved Use Permit Modification No. P15-00153-MOD to modify the existing 5,352 s.f. hospitality building, including converting approximately 375 s.f. of existing storage area to a commercial kitchen and tasting bar area, adding approximately 55 s.f. of storage space, adding of a tasting bar near the outdoor patio, and adding on premise consumption within the hospitality building and outdoor patio.
Building permits for construction of the winery development began processing in 2013. The property is currently developed with the winery hospitality building, cave, and a concrete outdoor work area in front of the cave. The original use permit approved a building in the center of the cave between the side cave portals. The building was never constructed and would be replaced by the current proposal. The existing, two-story hospitality building is yellow with white columns and ornamental design. The cave front is approximately 30 feet tall, measured from the ground floor level of the outdoor work area and cave portals. After initial construction the cave front was left as solid rock with stonework around the cave portals. In 2019, columns were added to the cave front and stonework in the shape of a face was constructed around the center of the cave, adding texture and detail. These elements were administratively authorized by the PBES Director, through Planning Division approval of a building permit. This application would locate the winery building in front of the cave, blocking the primary views of the cave design features.
Lot Line Adjustments (LLA) - Since the project was heard at the July 2023 Planning Commission hearing, two (2) LLAs were recorded, revising the parcel configuration. LLA 2077 was recorded October 12, 2023, and LLA 2106 was recorded December 26, 2024, resulting in the project parcel being referred to as “LLA 2106 Adjusted Parcel A” in the public notice and Mitigated Negative Declaration. The updated Assessor Parcel Number is 031-120-040.
Existing Development: The parcel is currently developed with an approximately 6,500 s.f. winery hospitality building, approximately 8,000 s.f. of caves, uncovered crush pads, parking lot, entry driveway, and 9.94 acres of vineyards. A stream, as defined by County standards in code section 18.108.030, runs north-south through the site. In compliance with CDFW Streambed Alteration Agreement No. 1600-2012-0012-3 (dated October 10, 2012), the stream enters a culvert on the northern side of the winery development and daylights through the center of the access driveways between the crush pad and parking, before entering a southern culvert that drains to the south toward the adjacent property.
Active Code Compliance Violations: There are no open cases on the property.
WINERY CHARACTERISTICS
Approved and Proposed Winery Characteristics
Winery Development Area Approved: 26,192 s.f. or .62 acres
Winery Development Area Proposed: No change
Winery Coverage Approved: 137,485 s.f. or 3.15 acres, approximately 15 % of the property.
Winery Coverage Proposed: No change (Maximum 25% or approximately 15 acres permitted, whichever is less)
Production Capacity Approved: 48,000 gallons per year
Production Capacity Proposed: 75,000 gallons per year
Accessory/Production Ratio Approved: 6,575 s.f. accessory/17,000 s.f. production - approximately 38%.
Accessory/Production Ratio Proposed: 11,000 s.f. accessory/42,000 s.f. production - approximately 26%.
Number of Employees Approved: 13 full-time and 2 part-time
Number of Employees Proposed: 17 full-time and 2 part-time
Visitation - Approved: By-appointment only - 40 guests/day Monday-Thursday and 75 guests/day Friday-Sunday
Visitation - Proposed: By-Appointment - 120 guests/day Monday-Thursday and 130 guests/day Friday-Sunday
Marketing Program - Approved: 31 events. Includes 27 events per year with up to 24 guests per event; two (2) events per year with up to 49 guests; one (1) event per year with up to 100 guests; and one (1) event per year with up to 300 guests
Marketing Program - Proposed: 37 events. In addition to the existing events, six (6) events per year with up to 120 guests
Days of Operation - Approved: Monday through Sunday
Days of Operation - Proposed: No change
Hours of Operation - Production - Approved: 7:00 a.m. - 6:00 p.m.
Hours of Operation - Production - Proposed: No change
Hours of Operation - Visitation - Approved: 11:00 a.m. - 6:00 p.m.
Hours of Operation - Visitation - Proposed: No change
Cave - Approved: 16,000 s.f. Type 3
Cave - Existing: 8,000 s.f. with additional currently under construction Type 3
Cave - Proposed: 16,500 s.f. for a total of 32,500 s.f. Type 3
Parking - Approved: 49
Parking - Existing: 54
Parking - Proposed: 54 Total parking spaces. Recognize total existing spaces.
Setbacks
Required Property Line setbacks: 20 feet
Existing Property Line setbacks: All existing and proposed winery development exceeds 100 feet from the property lines.
Required Road setback: 600 feet from State Highway 29 and 300 feet from Yount Mill Road.
Existing Road setback: The original winery Use Permit P09-00185 included approval of Variance P09-00492-UP which allowed portions of the winery development to be developed 520 feet from State Highway 29. Use Permit Modification P13-00054-MOD permitted replacement of an equipment storage building with an approximately 2,300 s.f. hospitality building, located no closer than 520 feet from the highway. The hospitality building meets the 300-foot setback from Yount Mill Road.
Proposed Road setback: The proposed winery building is located 600 feet from the highway and more than 300 feet from Yount Mill Road.
Adjacent General Plan Designation/ Zoning / Land Use:
All surrounding properties have a General Plan designation of Agricultural Resource (AR). The Zoning designation of most surrounding properties is Agricultural Preserve (AP) and includes wineries, vineyards, residences, and some undeveloped parcels. The adjacent property to the south includes an operating Bed and Breakfast. One property across the highway is partially zoned Commercial Limited (CL) and currently operates Mustards Grill.
Nearby Wineries located within one (1) mile of the project - There are seven (7) wineries within one (1) mile of the project.
Discussion Points:
Setting - The project is located on a 21.7-acre parcel approximately 1.3 miles north of the Town of Yountville. The driveway is off State Highway 29 (SR 29). The parcel is currently developed with an approximately 6,500 s.f. winery hospitality building, an approximately 8,000 s.f. cave, uncovered crush pads, parking lot, entry driveway, and 9.94 acres of vineyards. Surrounding properties include residences, vineyards, wineries, and undeveloped land. The closest offsite residence is located on the parcel to the north, approximately 300 feet from the existing hospitality building and approximately 400 feet from the new winery building.
Winery Proposal - The proposal is to modify an existing winery Use Permit to increase production, number of employees, and number of visitors. The project would modify the existing marketing plan and permit on-premises consumption in additional areas on site. Physical changes on site include construction of an approximately 10,500 s.f. winery building with a 700 s.f. lounge building, hospitality areas on the second patio level, creation of the Grotto courtyard between the new winery building and existing cave front, an approximately 16,500 s.f. cave expansion, including a commercial kitchen, cabanas on the existing hospitality building patio, and additional parking spaces. The winery building would be located in approximately the same location as a previously approved, but unbuilt 18,000 s.f. building. The winery will continue to use the existing hold and haul system for process wastewater. An option for future installation of a system to treat process waste onsite and reuse for irrigation was also evaluated.
Production - The winery is currently permitted for 48,000 gallons of production, with the request to increase to 75,000 gallons. [Note - The original 2018 request included an increase to 100,000 gallons.] As discussed at the prior hearings, the winery caves are currently used to cellar barrels for the fermentation process of making wine. Other production activities, including crush, racking, and bottling, are completed at other wineries owned by the applicant. Construction of the building would create space for all wine processing activities to occur on site, from receiving fruit, fermentation, barrel work, and bottling, with the expanded cave continuing use for barrel storage. Following construction of the building, the winemaker anticipates getting into a “full” production by year two. Please refer to Attachment F.
Visitation and Marketing - The winery is currently permitted by appointment tours and tastings for 40 visitors per day Monday-Thursday and 75 visitors per day Friday-Sunday. The proposed project would increase visitation to 120 visitors per day Monday-Thursday and to 130 visitors per day Friday-Sunday. [Note - The original 2018 request included an increase to 125 visitors Monday-Thursday.] Weekly visitation would increase from 385 visitors to 870 visitors, with annual visitation increasing from 20,020 to 45,240. There are no changes to visitation hours of 11 a.m. to 6 p.m.
The number of marketing events would increase from 31 events to 37 events, with the addition of (6) events with up to 120 guests per event. [Note - The original 2018 request proposed 23 new events, including 19 events with up to 120 guests and four (4) events with up to 400 guests.] Total event guests would increase from 1,146 guests to 1,866 guests. On Monday-Thursday events would occur between 6 p.m. and 10 p.m. and Friday-Sunday events would occur between 11 a.m. and 1p.m. or 5 p.m. and 10 p.m.
The maximum number of annual guests at the winery would increase from 21,116 to 47,106.
Employees - The winery proposes to increase full-time employees from 13 to 17. There is no change to the permitted two (2) part-time employees.
Traffic, VMT Analysis, Parking - The County maintains a set of Transportation Impact Study Guidelines (TIS Guidelines) that define situations and project characteristics that trigger the need to prepare a TIS. The purpose of a TIS is to identify whether the project is likely to cause adverse physical or operational changes on a County roadway, bridge, bikeway or other transportation facility, to determine whether the project should be required to implement or contribute to improvement measures to address those changes, and to ensure that the project is developed consistent with the County’s transportation plans and policies. Based on the County’s Trip Generation worksheet, the proposed project does not exceed the threshold requiring preparation of a traffic study, 110 net new daily trips, therefore the project is not required to prepare a traffic study. However, the project included a Traffic Impact Study (TIS) prepared by W-Trans, dated April 21, 2020, that was prepared prior to the County’s updated TIS Guidelines which went into effect in January 2022. Analysis of project Level of Service (LOS) impacts is no longer applicable to the CEQA analysis, however the TIS recommends limiting times on scheduling of trips in order to limit impacts to the LOS in the project area. Recommendations have been included in conditions of approval from the Department of Public Works. Recommendations include scheduling marketing events such that no trips would be generated during peak hours in order to limit impacts to LOS. Specifically, large events should be scheduled to start and end outside peak periods for traffic on SR 29; between 4:00 and 6:00 p.m. on weekdays and between 1:00 and 3:00 p.m. on weekends. The trip generation does not exceed the threshold requiring a Vehicle Miles Traveled (VMT) analysis, the TIS includes the applicant’s proposal for a Traffic Demand Management (TDM) Plan with the intent of reducing VMT. The winery’s TDM program would include items such as: provide information, encouragement, and access to non-motorized travel options for both employees and guests, to reduce the number of vehicle trips and overall VMT. Report recommendations include carpool incentives, financial incentives for carpooling or biking to work, guaranteed ride home program, bicycle parking, shuttle service, and designation of a Transportation Coordinator. The winery currently has 49 parking spaces and proposes to add five (5) additional spaces for a total of 54 parking spaces. The TIS determined that the proposed parking supply is adequate for the anticipated demand during typical harvest operation, but inadequate for the 120-person and 400-person events. For large events the applicant shall provide shuttle services or arrange for guests to park off site. Please refer to Attachment B - COA No. 4.3.i. W-Trans prepared an Addendum the TIS, dated September 20, 2024, noting that the reduced project description would result in less trips and therefore would not change the previous analysis of the project.
Noise - Production activities would take place in the winery building, limiting production related noise. Visitation and marketing events would increase with this modification and new areas would be permitted for visitation and outdoor tastings. Cabanas are proposed in the outdoor area adjacent to the existing hospitality building. The cabanas would be tucked into the existing trees and landscaping in the outdoor area. The hospitality building would remain between the outdoor area and the closest residence. In addition to the cabanas the proposed Grotto courtyard and the second story terrace at the new winery building could be used for hospitality. The closest portion of the winery building second story outdoor area is approximately 310 feet from the closest residence. The Grotto is approximately 20 feet below the second story and effectively enclosed by the proposed winery building and existing cave front.
The proposed project includes use of outdoor speakers at the existing hospitality building outdoor patio, and the new Grotto, and winery building second story terrace. The speakers would be used to play background music during visitation hours and daytime events (11:00 a.m. and 1:00 p.m.). A study was prepared by Illingworth & Rodkin, Inc. dated November 22, 2021. Please refer to Attachment K. The study summarizes the results of noise measurements taken to quantify the expected sound levels produced by outdoor speakers to determine the sound levels at the nearest residential property lines. The nearest garden speaker to this residential property would be located approximately 60 feet from the common property line and the nearest winery building speakers to this residential property would be located approximately 110 feet from the common property line. The residence is approximately 200 to 250 feet from the property lines, resulting in distances of approximately 260 feet and 310 feet from the speaker location to the closest portion of the residence. At a distance of 60 feet, representing the closest property line, the typical noise level produced by the speaker (61 dBA L50) would be reduced to 40 dBA L50 assuming hemispherical spreading losses and no additional attenuation from intervening structures. At 110 feet, the typical noise level produced by the speaker would be 34 dBA L50 or less. The calculated noise levels would meet the noise limit established by Napa County set at 45 dBA L50. At these distances, the sound levels from background music would be 25 dBA L50 or less and inaudible above other ambient sources of noise in the project vicinity. The nearest residential property to the north, along Yount Mill Road, is located over 450 feet from the nearest speakers proposed within the tasting room garden. At a distance of 450 feet, background music sound levels are calculated to be 22 dBA L50 or less. Noise levels produced by background music in the Grotto and winery building would be less. It was observed during the noise survey, that background music played at typical levels would not be audible above other ambient noise sources in the areas. Similarly, noise levels would be inaudible at distant receptors to the west and southwest because of the greater distances separating the noise source and receptors and the proximity of these receptors to SR 29. As stated above, use of the outdoor speakers for background music only, could be used during daytime events (11:00 a.m. and 1:00 p.m.), but would not be permitted for events occurring during evening hours (after 6:00 p.m.). Use of other outdoor amplified music or sound systems would not be permitted for use at any hospitality or marketing events. A condition of approval has been added to ensure compliance with this restriction. Please refer to Attachment B - COA No. 4.20.b. Continuing enforcement of Napa County’s Noise Ordinance by the Code Enforcement Division and the Napa County Sheriff would further ensure that marketing events and other winery activities do not create a significant noise impact. Events and non-amplified music, excluding quiet clean-up, are required to finish by 10:00 p.m.
Groundwater Availability - A Water Availability Analysis (WAA) was prepared by O’Connor Environmental Inc. (OEI), dated February 20, 2025, and an Addendum to the WAA was submitted on July 9, 2025. The report includes Tier 1, Tier 2, and Tier 3 analyses. The Addendum was submitted to correct two items. First, the Addendum notes a reduction in the vineyard acreage due to the removal of additional vineyard during installation of solar panels. The reduced vineyard size lowers the water use estimate related to irrigation and the total proposed water use. The revised numbers are included in the discussion sections below. Second, following the 2024 Lot Line Adjustment it was thought that Ag Well 20 was on the newly configured parcel and it was proposed that the well would continue to be used for irrigation of a portion of the vineyards. Upon site inspections it was determined that the well was not on the project parcel. The Addendum clarifies this and notes that the existing Project Well will be used to provide water to the project.
The Engineering Division has evaluated the project based on information provided by the applicant, its location, and available geologic and hydrologic information and has determined the WAA to be complete and reasonable. Engineering found the WAA technically adequate as it relates to Napa County’s water use criteria, well and spring interference, groundwater/surface water interaction pursuant to Napa County’s WAA Guidelines, Governor’s Executive Order N-7-22/N-3-23, Napa Valley Subbasin Groundwater Sustainability Plan, and the Public Trust Doctrine.
Tier 1 - Water Use Criteria - Groundwater Demand and Recharge Analysis
The existing Project Well is located near the winery development and between the vineyards. Current water use includes winery operations, winery landscaping, and vineyard irrigation. Existing water use on the project parcel is estimated to be 11.02 ac-ft per year. Although the project would increase water use associated with production activities, guests, and employees, due to planned changes in vineyard irrigation practices, improved management of water resources, and a reduction in vineyard acreage, the overall estimated water use on the property would decrease to 9.5 ac-ft per year. Vineyard irrigation rates are planned to be reduced from 0.75 ac-ft to 0.5 ac-ft. Following implementation, the anticipated water use of 9.5 ac-ft per year, is an overall reduction in water use of 1.52 ac-ft per year, representing a 13.8% decrease.
Because the Project Well is located outside of the GSA Subbasin, a parcel-specific groundwater recharge analysis was prepared. The groundwater recharge was estimated using a Soil Water Balance (SWB) of Napa County developed by OEI. This model implements the U.S. Geologic Survey’s SWB modeling software and produces a spatially distributed estimate of annual recharge, with recharge potential characterized by the percentage of annual precipitation available for recharge, following consideration of local evapotranspiration, runoff, and soil moisture. For the approximately 21.7-acre project parcel, the calculations yield an estimated average annual recharge of 9.8 acre-ft/yr.
The proposed 9.5 ac-ft/year demand is equivalent to 96.6% of the estimated 9.8 acre-ft of average annual recharge. The project hydrologist opines that given that this project would result in a net decrease in demand, water use associated with the proposed project is highly unlikely to result in reductions in groundwater levels or depletion of groundwater resources over time relative to existing conditions.
Tier 2 Well and Spring Interference
On January 10, 2024, the County released the “Napa County Interim Napa County Well Permit Standards and WAA Requirements - January 2024”. This document states that a Tier 2 analysis is only required for an increase in groundwater use. As discussed above, the overall water use on the parcel will decrease.
Tier 3 Groundwater/Surface Water Interaction Criteria
The Project Well is located approximately 1,300 feet from Lincoln Creek, a county designated Significant Stream. The County’s Water Availability Analysis Guidance Document provides distance standards that are expected to preclude any significant adverse effects on surface waters based on well pumping rates, aquifer hydraulic conductivity, and well construction characteristics. These distance standards are presented in Tables 3, 4 & 5 within the Guidance Document. As stated in the Application of Public Trust Doctrine to Projects Dependent on Groundwater, dated January 10, 2024, applicants can satisfy the Tier 3 or equivalent analysis by demonstrating compliance with Tables 3, 4, and 5. The Project Well meets criteria in Table 4 for a “low capacity well” pumping at 20 gpm. Therefore, the Project Well is not expected to have a significant adverse effect on Lincoln Creek.
The report details several additional hydrogeologic factors and historic data that demonstrate that impacts of groundwater pumping for the proposed project upon flows in Lincoln Creek are not likely to be substantial.
• Lincoln Creek is an intermittent stream that has a short seasonal period in winter and/or spring when a hydraulic connection with groundwater exists; this period of connectivity does not coincide with periods of high groundwater demand.
• The relatively low hydraulic conductivity of the Sonoma Volcanics (~0.0001 ft/day) from which the project well pumps groundwater relative to the hydraulic conductivity of the alluvial aquifer underlying Lincoln Creek (>10 ft/day) suggests that the rate of potential groundwater flow from the Sonoma Volcanics to the adjacent/overlying alluvial aquifer is low.
• Groundwater elevation in the Project Well (Well 1) measured in September 2006 (66 ft below ground surface (bgs) or ~114 ft above mean sea level (amsl)) and in August 2013 (73 ft bgs or ~107 ft amsl) lies below the streambed elevation of Lincoln Creek (~125 ft amsl) at its nearest proximity to the project well (~1,300 ft).
• Drawdown of groundwater elevation in the project well (Well 1) during a 24-hr pump test at 20 gpm in August 2013 was only 20 ft with 93% recovery within 24 hours indicates that the pressure head in the Sonoma Volcanics confined aquifer is relatively high and the operational pumping does not excessively lower the groundwater elevation. This indicates that potential groundwater movement that may occur from the Sonoma Volcanics to the alluvium underlying Lincoln Creek is unlikely to be significantly affected.
Based on the data and hydrogeology of the project area, the project hydrologist opined that the proposed project will not have a significant impact on seasonal flows in Lincoln Creek.
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. The January 10, 2024, Application of Public Trust Doctrine memorandum states that a Tier 3 review or equivalent analysis is the County’s adopted method for complying with its duties under the Doctrine. The project WAA included a Tier 3 analysis, concluding the Project Well meets criteria in Table 4 of the Guidance Document, therefore, the Project Well is not expected to have a significant adverse effect on Lincoln Creek. The County has satisfied its duty to consider impacts to trust resources and no further analysis is required. The project will include the County’s project specific Conditions of Approval setting a limitation on groundwater use for the parcel to the proposed water use of 9.5 ac-ft/year. The Project Well will be required to install and maintain pumping equipment that will restrict the pumping rate at less than 20 gpm.
The applicant will be required to complete installation of well meters and conduct monthly well monitoring and reporting per the project Groundwater Management Plan, which requires approval by the County [COA Nos. 4.20.a., 6.15.a, and 6.15.b.]. The conditions would also include the potential to modify/alter permitted uses on site should groundwater resources become insufficient to supply the use. Impacts would be less than significant.
Wastewater system - The winery has separate wastewater treatment systems for processing domestic wastewater and process wastewater. The Onsite Sanitary Wastewater Disposal Feasibility Study, prepared by Applied Civil Engineering, dated April 25, 2025, evaluated the existing sanitary wastewater system. The winery is currently serviced by a subsurface drip type sanitary wastewater system, consisting of a series of septic tanks and pretreatment with disposal via an existing subsurface drip system. The design capacity is 1,500 gallons per day according to design documents. The design capacity includes an allowance for a residence. No residence has been built and connected to the system, so the full capacity is available for the winery sanitary wastewater needs. The peak sanitary wastewater flow from the winery is calculated based on the number of winery employees, the number of daily visitors for tastings and the number of guests attending scheduled marketing events. In accordance with Table 4 of the Napa County “Regulations for Design, Construction, and Installation of Alternative Sewage Treatment Systems” a design flow rate of 15 gallons per day (gpd) per employee and 3 gpd per visitor for tastings was utilized. Table 4 does not specifically address design of wastewater flows for guests at marketing events. For marketing events that will have catered meals that are prepared offsite 5 gallons of wastewater is estimated per guest assuming there will be no food preparation or cleanup onsite. For events with meals prepared onsite, 15 gallons of wastewater is estimated per guest, similar to a restaurant. All events with more than 100 guests will be catered and utilize portable toilets and therefore are not included in the analysis. Based on these assumptions, the peak winery sanitary wastewater flow is estimated to be 1,280 gpd. The predicted peak flow for the proposed winery operational characteristics (1,280 gpd) is less than the design capacity of the existing sanitary wastewater disposal system (1,500 gpd). Therefore, no design adjustments are needed to accommodate the proposed use permit modification characteristics. The original design of the sanitary wastewater system includes the 200% reserve area required by County code. The calculations presented above illustrate that the sanitary wastewater flows associated with the proposed Use Permit Modification will not exceed the capacity of the existing sanitary wastewater system.
The Onsite Process Wastewater Disposal Feasibility Study, prepared by Applied Civil Engineering, dated April 25, 2025, demonstrates that the estimated peak winery process wastewater flow associated with the increase in production is less than the capacity of the existing hold and haul system serving the winery. Therefore, no design adjustments are needed to accommodate the proposed use permit modification characteristics. The study also analyzed the potential to install an onsite process wastewater treatment and re-use system. In this scenario the process wastewater will continue to be kept completely separate from the domestic waste stream and will be pretreated to land application strength requirements in accordance with the Statewide General Waste Discharge Requirements (WDRs) for Wineries in California. As noted in the memo from the Environmental Health Division the winery operator is not required to enroll for coverage under the State WDR while utilizing hold and haul. In the future if the hold and haul system is replaced with a system discharging process water onsite, the operator will be required to enroll for coverage and comply with monitoring and reporting as specified.
Water System - In accordance with California Health and Safety Code Section 116275 (o), the existing domestic water system is currently classified as a transient, non-community system. The system is comprised of an onsite supply well, three 85,000-gallon water tanks, and supply lines. The system is operated under State ID Water System No. CA2800048 and is owned and operated by Yountville Vineyards LLC., a private corporation. Because the system is existing, a water system feasibility report was not required to be submitted. The increase in employees and visitors does not result in operational levels that would change the classification of the water system. Therefore, no modifications to the system are required.
Greenhouse Gas - On the GHG Best Management Practices (BMP) Checklist submitted with the use permit application, April 16, 2018, the applicant identified numerous GHG reduction BMPs that the operators are currently implementing at the winery, including: energy conserving lighting, water efficient fixtures, water efficient landscaping, local food production and composting food and garden materials, shade trees for natural cooling, electric vehicle charging stations, caves used for barrel storage, and 70-80% cover crop and reuse of vegetation biomass. Additional measures were also identified. Condition of approval No. 4.20.b will require the continued implementation of the existing measures checked on the form. Evidence shall be provided to staff upon request.
Staff has recommended a project specific condition to prohibit the use of natural gas appliances or plumbing. Additionally, at the time of construction the project will be required to comply with the California Building Code, which is currently being updated to include regulations to assist in the reduction of air quality impacts associated with construction. Regarding electrical usage, there is currently a building permit under review for a solar array on the property that could be used to serve the winery. Any new construction will be required to install energy efficient fixtures complying with CA Building Code Title 24 standards. The project will also be required to comply with the recently adopted version of CALGreen Tier 2. Staff has included a project specific condition to ensure this is reviewed and implemented at the time of construction through adherence to the California Building Code. Please refer to Attachment B - COA 6.15.c, 6.15.d. and 6.15.e.
As discussed above, the applicant has proposed a Travel Demand Management (TDM) program to implement operational procedures to reduce daily trips and overall vehicle miles traveled. The winery’s TDM program could provide information, encouragement, and access to non-motorized travel options for both employees and guests, to reduce the number of vehicle trips and overall VMT. Report recommendations include: Carpool incentives, financial incentives for carpooling or biking to work, guaranteed ride home program, bicycle parking, shuttle service, and designation of a Transportation Coordinator.
Tribal Cultural Resources - On March 29, 2022, County Staff sent invitations to consult on the proposed project to Native American tribes who had a cultural interest in the area and who as of that date had requested to be invited to consult on projects, in accordance with the requirements of Public Resources Code section 21080.3.1. Staff received a response from the Yocha Dehe Tribe on April 12, 2022; the Tribe did not request to consult or provide comments.
Grape Sourcing - The parcel has 9.94 acres of vineyards. The applicant owns multiple other winery and vineyard properties in the County and stated they can accommodate the increase in production.
Environmental Document - The Initial Study/Mitigated Negative Declaration (MND) and the MMRP was submitted to the SCH on May 13, 2025, (SCH #2025050553) for a 30-day review. The MND includes a recommended mitigation measure provided by CDFW, following their review of the 2023 Initial Study Negative Declaration. According to the proposed Mitigated Negative Declaration, the proposed project would not have any potentially significant environmental impacts with the incorporation of a mitigation measure for Swainson’s Hawk. Proposed Mitigation Measure (MM) BIO-1 Swainson’s Hawk Surveys, Avoidance, and Foraging Habitat Mitigation requires pre-construction surveys if Project activities are scheduled during the nesting season for Swainson’s hawk (March 1 to September 15). The mitigation details are included in the MND, Recommended Conditions of Approval (No. COA 6.12.a), Project Revision Statement, and the Mitigation Monitoring and Reporting Program (MMRP). The Addendum to the WAA was received following circulation of the MND and the completion of the public comment period. The analysis of groundwater use found that potential impacts to groundwater resources would be less than significant; therefore, evaluation of the reduced water use, as presented in the Addendum, would result in the same findings. The change does not meet the criteria of CEQA Guidelines Section 15073.5 requiring recirculation of an MND.
Conditions of Approval - Infrastructure improvements are required to be completed prior to beginning an increase in production, employees, visitation, and marketing. A condition of approval regarding the timing of these improvements has been added. Please refer to Attachment B - COA No. 4.20.c.
Public Comments - Several comment letters were received in conjunction with the April 19, 2023, June 7, 2023 (Continuance only) and July 13, 2023, Planning Commission hearings. The comments, included as attachments to the prior Planning Commission Hearing staff reports, are not included in Attachment O, but are available via the links to the staff reports provided in the Executive Summary. At that time, the Commissioners and members of the public requested additional information and analysis on project components. In response, the applicant resubmitted a revised project description, reducing a number of operational components. As discussed above, the 2023 recommendations of CDFW have been incorporated into the Mitigated Negative Declaration and Conditions of Approval. The June 4, 2025, informational letter from Caltrans has been provided to the applicant and is included in Attachment O.
Decision Making Options:
As noted in the Executive Summary, staff recommends approval of the project subject to conditions. Decision making options also include a reduced-intensity project alternative, and a no project alternative (denial of the requested Use Permit Major Modification).
Option 1 - Approve Applicant's Proposal (Staff's Recommendation)
Disposition - The proposed project includes operational changes, construction of new structures, and infrastructure improvements. Operational changes include an increase in production along with an increase in employees, by-appointment visitation, and a revised marketing plan. Proposed physical improvements include construction of a winery building and accessory structures, and the design of a potential future on-site process wastewater treatment system. This option has been analyzed for environmental impacts, which were found to be less than significant with the incorporation of mitigation measures related to biological resources. The request was found to be consistent with the Zoning Ordinance and applicable General Plan policies.
Action Required - Follow the proposed action listed in the Executive Summary. If conditions of approval are to be amended, specify conditions to be amended at the time the motion is made.
Option 2 - Revised Project Request
Disposition - All potential environmental impacts of the project, as proposed, have been found to be less than significant with the incorporation of mitigation measures related to biological resources and conditions of approval. However, this option provides the Planning Commission, at their discretion, the ability to further reduce potential impacts, such as decreasing the winery's production level, maximum daily visitation numbers, marketing activities, and/or the number of employees. If the Planning Commission elects to pursue this option, the recommended conditions of approval would need to reflect the revised components.
Action Required - Follow proposed actions listed in the Executive Summary and amend scope and applicable conditions of approval. The item may need to be continued to a future date if significant revisions to the recommended conditions of approval are desired.
Option 3 - Deny Applicant’s Proposal
Disposition - In the event the Commission determines that the project does not or cannot meet the required findings for the granting of a Use Permit major modification, Commissioners should identify what aspect or aspects of the project are in conflict with the required findings. State Law requires the Commission to adopt findings, based on the General Plan and County Code, setting forth why the proposed Use Permit Major modification is not being approved.
Action Required - Commission would deny the project.
Option 4 - Continuance Option
The Commission may continue an item to a future hearing date at its own discretion.
SUPPORTING DOCUMENTS
A. Recommended Findings
B. Recommended Conditions of Approval and Final Agency Approval Memos
C. Previous Project Conditions
D. Initial Study/Mitigated Negative Declaration SCH #2025050553 and Mitigation Monitoring & Reporting Plan
E. Use Permit Major Modification Application Packet
F. Applicant Response to 2023 Action Items
G. Water Availability Analysis and Water Availability Analysis Addendum
H. Onsite Process Wastewater Disposal Feasibility Study
I. Onsite Sanitary Wastewater Disposal Feasibility Study
J. Air Quality and GHG Emissions Assessment
K. Environmental Noise Assessment - Background Music Sound Levels Analysis
L. Traffic Impact Study and Addendum to the Traffic Impact Study
M. Graphics and Use Permit Major Modification Plan Set
N. Winery Comparison Analysis and Summary of Changes
O. Public Comments