To: The Board of Supervisors of Sonoma County
Department or Agency Name(s): Permit Sonoma
Staff Name and Phone Number: Scott Orr; Mark Shurvinton, (707) 565-1900
Vote Requirement: Majority
Supervisorial District(s): First
Title:
Title
10:12 A.M. Zone Change to remove the Z (Accessory Dwelling Unit Exclusion) Combining District and Certificate of Modification to remove Note 15 from Parcel Map “PLP05-0102”; 19651 7th Street East, Sonoma (Permit Sonoma File No. PLP23-0010).
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Recommended Action:
Recommended action
Permit Sonoma recommends that the Board of Supervisors conduct a public hearing and adopt an Ordinance finding the project exempt from the California Environmental Quality Act under CEQA Guidelines Section 15305 (minor alterations in land use limitations) and California Public Resources Code Section 21080.17 and approve a Zone Change to remove the Z (Accessory Dwelling Unit Exclusion) Combining District and a Certificate of Modification to remove Note 15 on Parcel Map PLP05-0102 at 19651 7th Street East, Sonoma; APN 127-291-037. (Permit Sonoma File No. PLP23-0010) (First District)
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Executive Summary:
The project proposes 1) a Zone Change to remove the Z (Accessory Dwelling Unit Exclusion) Combining District and 2) a Certificate of Modification to remove Note 15 from Parcel Map PLP05-0102, on a 4.02-acre parcel zoned Agriculture and Residential (AR), located at 19651 7th Street East in Sonoma. The subject parcel is currently developed with a single-family dwelling, accessory structures, and vineyard. The request would allow for an Accessory Dwelling Unit (ADU) to be developed on the subject property in the future.
The Planning Commission adopted Resolution No. 25-09 on September 4, 2025, which recommended your Board approve the Zone Change to remove the Z Combining District from the subject parcel and the Certificate of Modification to remove Note 15 from Parcel Map PLP05-0102.
Discussion:
Project Site and Context
The subject parcel is 4.02 acres in size and is located on 7th Street East, approximately 100 feet east of the City of Sonoma. The parcel is developed with a single-family dwelling, accessory structures and vineyard, and is served by an existing on-site well and septic system.
General Plan and Zoning Discussion
The subject parcel at 19651 7th Street East (APN 127-291-037) was created through recordation of Parcel Map PLP05-0102 on December 15, 2009 (Book 736, Page 33-35, Sonoma County Records). To ensure that development on the resulting parcels would not exceed the allowed residential density of the original parcel, the project was conditioned to limit the number of dwelling units to one per parcel. Condition of approval #41 for PLP05-0102 required a note on the map, Note 15 (“15. No second units shall be allowed on these lots.”), to preclude the construction of a second dwelling unit on each of the resulting parcels. In addition, condition of approval #38 of PLP05-0102 required a Zone Change to add the Z (Accessory Dwelling Unit Exclusion) Combining District, to further ensure ADUs would not be constructed on the resulting parcels.
Z Combining District
The Z combining district was applied to the subject property during the implementation of the 1989 General Plan. The purpose of Sec. 26-76-005 of the Sonoma County Zoning Code (Z - Accessory Dwelling Unit Exclusion Combining District) is to provide for the exclusion of accessory dwelling units in specific areas of Sonoma County. This includes areas where there is an inadequate supply of water for drinking or firefighting, where there is inadequate sewer services or danger of groundwater contamination, where the addition of accessory dwelling units would contribute to existing traffic hazards or increase the burden on heavily impacted streets, roads or highways, and where, because of topography, access or vegetation, there is a significant fire hazard.
Zone Change
Applications to remove the Z combining district must be consistent with Article 76 of the Sonoma County Zoning Code, Accessory Dwelling Unit Exclusion Combining District. The proposal to remove the Z (Accessory Dwelling Unit Exclusion) Combining district is recommended because the project addresses the following zoning restrictions:
a) Areas where there is an inadequate supply of water for drinking or firefighting purposes.
The parcel is within a Class 1 Groundwater Availability Area, which is designated as a major groundwater basin. The parcel is additionally located within the Sonoma Valley basin, which is designated as high priority groundwater basin by the California Department of Water Resources. The adopted Sonoma Valley Groundwater Sustainability Plan has documented a groundwater depression and declining groundwater levels in the immediate vicinity of the project site, suggesting the local aquifer is in a condition of overdraft. For this reason, Permit Sonoma’s staff geologist requested a report demonstrating that the project will result in zero net increase in groundwater extraction. The applicant provided a report demonstrating to the satisfaction of the staff geologist, that removal of existing vineyard would yield no net increase in groundwater use on the subject parcel, and that sufficient water is available to serve a future accessory dwelling unit.
b) Areas where there are inadequate sewer services or danger of groundwater contamination.
The parcel is served by an existing septic system permitted under Septic Permit No. SEP16-0170, which meets the demand for the single-family dwelling and accessory structures currently on-site. Any increase in septic capacity must be approved by the Permit Sonoma Well and Septic Division.
c) Areas where the addition of accessory dwelling units would contribute to existing traffic hazards or increase the burden on heavily impacted streets, roads, or highways.
The subject parcel is located on 7th Street East, which is a County maintained roadway, and has adequate ingress and egress through a private driveway. The potential addition of an ADU on the parcel is not expected to contribute to existing traffic hazards or increase the burden on surrounding roadways.
d) Areas where, because of topography, access or vegetation, there is significant fire hazard.
The subject property is located within a Local Responsibility Area, and per the Local Responsibility Area Fire Hazard Severity Zone Maps issued by CALFIRE on February 24, 2025, the parcel is not located within an area with elevated fire hazard. Any future building permits would be required to comply with Fire Safe Regulations for new development, including access, water supply, property line setbacks, construction techniques, and defensible space.
Certificate of Modification
To amend a recorded Subdivision Map, specific findings, as required by Section 66472.1 of the Subdivision Map Act and Chapter 25 of the Sonoma County Code, must be made. As included in the attached resolution, these findings are as follows:
1. That there are changes in circumstances which make certain conditions on the map no longer appropriate or necessary.
The Sonoma County General Plan 2020 contains policies supporting the removal of unnecessary constraints to the provision of affordable housing, including the removal of prior ADU prohibitions where there are no water, flooding, or sewage treatment issues:
Policy HE-5g: Continue to encourage the retention and further construction of small rental units such as accessory dwelling units, studios, and single-room occupancy (SRO) units.
Removing ADU restrictions on the subject parcel is consistent with the provisions of the Sonoma County General Plan 2020. While the restrictions were placed on the parcels resulting from PLP05-0102 to prevent a second unit from exceeding the allowable residential density of the parcels, changes have been made at the state level which establish that ADUs no longer count towards the allowed residential density of a parcel. As a result of these changes, the issue of density is no longer a valid justification to prohibit the construction of an ADU on the subject parcel.
2. That the proposed modifications do not impose any additional burden on the present fee owner of the property.
The current property owner of the subject lot has requested the Certificate of Modification because they would like to construct a new ADU. As such, the present property owner is aware of the modification and no additional burden will be imposed.
3. The modifications do not alter any right, title, or interest in the real property reflected on the recorded map.
The interest in the property of owners of the other Lots as shown on the recorded map is not affected as the property owner has consented to the removal of the note on the map, and the removal of the note on the map is consistent with the previous request made by the property owner.
4. The map, as modified, conforms to all the provisions of the Subdivision Map Act and local implementation ordinances (Section 66472.1 of the Subdivision Map Act and Section 25-13.8 of the Sonoma County Subdivision Ordinance).
In accordance with the provisions of the Subdivision Map Act, an amended Final Map or Certificate of Modification will be recorded depicting requested modifications as depicted on Parcel 2 of Parcel Map “PLP05-0102”, recorded in Book 736, Page 33-35 of Sonoma County Official Records. The amended Final Map or Certificate of Modification will conform to all the provisions of the Subdivision Map Act and local ordinances, as originally approved. Thereby, staff believes that all of the findings required by the California Subdivision Map Act can be made.
Additional details on this proposal are available in the attached Planning Commission Staff report, dated September 4, 2025 (Attachment 2).
The Planning Commission voted 5-0 on September 4, 2025, to adopt a resolution finding the project exempt from CEQA and recommending approval to the Board of Supervisors for the requested Zone Change and Certificate of Modification.
Strategic Plan:
“Healthy and Safe Communities: Goal 3. In collaboration with cities, increase affordable housing development near public transportation and easy access to services.”
This application requests relief from limitations on the applicant’s ability to construct an ADU on a parcel within ¼ mile of the City of Sonoma. The County recognizes that ADUs are affordable by design and are an essential component of meeting the County’s housing targets. Approving the requested certificate of modification and rezone would facilitate the creation of an ADU and in doing so, would support meeting the Board’s strategic objective to support quality, affordable and equitable housing.
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
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Prior Board Actions:
N/A
Fiscal Summary
Narrative Explanation of Fiscal Impacts:
This is an at-cost project for which project costs are the responsibility of the applicant.
Narrative Explanation of Staffing Impacts (If Required):
N/A
Attachments:
Attachment 1: PLP23-0010 Draft Board of Supervisors Ordinance
Attachment 1a: PLP23-0010 Existing and Proposed Zoning Map
Attachment 2: PLP23-0010 Planning Commission Staff Report
Attachment 3: PLP23-0010 Planning Commission Resolution No. 25-09 with Exhibit A Conditions of Approval
Attachment 4: PLP23-0010 Property Owners’ Consent
Attachment 5: PLP23-0010 Staff PowerPoint Presentation
Related Items “On File” with the Clerk of the Board:
N/A