To: Board of Supervisors
From: Planning and Building Department
Agenda Section: Departmental
Vote Requirement: Majority
SUBJECT:
title
Assessment of a Potential Reduction in the Minimum Acreage Required for Subdivisions in the Jacoby Creek Community Planning Area.
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RECOMMENDATION(S):
Recommendation
That the Board of Supervisors:
1. Receive the report prepared by staff, and direct staff to undertake further action as appropriate.
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STRATEGIC PLAN:
This action supports the following areas of your Board’s Strategic Plan.
Area of Focus: Housing for All
Strategic Plan Category: 4002 - Increase and prioritize housing development
DISCUSSION:
Executive Summary
This report is to allow the Board of Supervisors to decide whether to initiate a process of changing the General Plan, Jacoby Creek Community Plan and area zoning to allow additional parcels in the Jacoby Creek area. This request came in response to an appeal of a Parcel Map Subdivision which would require all these actions, but in so doing the Board asked to expand the analysis to determine how many more units could be obtained. The work to date has raised awareness that the area is highly variable in the depth of groundwater which could result in a potential for pollution of groundwater if too many units were allowed. To proceed additional research and potentially studies are needed to understand the conditions and how many units could be located in the area while protecting groundwater resources.
This assessment was initiated by an appeal of the Humboldt County Planning Commission’s Aug. 7, 2025 denial of a Parcel Map Subdivision (PMS) application to divide an approximately 4.55-acre parcel into two parcels of approximately 1.4 acres (Parcel 1) and 3.2 acres (Parcel 2). Policies in the Jacoby Creek Community Plan require a minimum of 5 acres for parcels served by wells and onsite wastewater treatment systems (OWTS) and the minimum parcel size under the General Plan designation and zone district is 2.5 acres. The appeal was heard by the Board on Sept. 9, 2025. A motion was made by Supervisor Bushnell, seconded by Supervisor Wilson, to continue the hearing to a date uncertain, with direction to staff to look at how many potential units could be created by changing the community plan policies and reducing the minimum lot size under the general plan and zoning, and to provide an estimate of the cost of funding the effort.
After preliminary analysis in consultation with the Division of Environmental Health (DEH), a minimum parcel size of 2 acres may be appropriate for parcels in this area that would be served by on-site wastewater treatment systems (OWTS) and private wells. Based on a minimum parcel size of 2 acres and accounting for various limiting factors, a maximum of 76 new parcels may be allowable by reducing the minimum allowable lot size to 2 acres. Planning and Building and DEH have been able to identify areas with non-standard OWTS reflecting shallow groundwater levels. The extent of these areas is general and has not been precisely mapped. If the Board directs the Planning and Building Department to pursue this, the effort will necessitate technical studies to complete environmental review under the California Environmental Quality Act (CEQA).
The current minimum acreage required in the Jacoby Creek area is dictated by the General Plan land use designation and zoning designation and is further limited by specific policies of the Jacoby Creek Community Plan. The zoning and land use designation of most of the residential area limits the minimum parcel size to 2.5 acres. The Jacoby Creek Community Plan policies include policies 26 and 27, and policy 39, which allow development at a density of one unit per 5 acres in the Urban Development Area without public water and sewer systems under specific conditions, require public water and sewer for development at General Plan densities (2.5 acres per parcel) within the Urban Development Area, and prohibits subdivision of lands designated Residential Estates to less than 5 acres unless public water systems are available, respectively. These policies apply to both the Urban Development Area and all parcels with a land use designation of Residential Estates (RE).
Analysis of the Minimum Acreage in the Jacoby Creek Area
The Planning and Building Department and Division of Environmental Health have estimated that the minimum parcel size required for subdivision may be as low as 2 acres for parcels with onsite water and wastewater systems. This estimate is based on the typical area needed to accommodate onsite wastewater treatments systems for a primary residence and accessory and junior dwelling units with required setbacks to property lines and wells. The estimate also includes additional allowances for building areas, utility easements, driveway areas. It is important to note the calculations involved in these estimates are heavily influenced by broad assumptions, which will not be applicable to all lots in the area. Specific on-site factors may preclude subdivisions even in the event of meeting the estimated minimum parcel size. These factors include but are not limited to parcel shape and configuration, groundwater level, slope, watercourses, or presence of neighboring wells.
New Housing Potential
Changing the policies outlined above to allow subdivisions in the Jacoby Creek Planning Area would change requirements for approximately 460 parcels. Of the 460 parcels included in the Urban Development Area and with a Residential Estates land use designation, approximately 124 parcels are large enough and have appropriate zoning and land use designation to allow for subdivisions. After consultation with DEH, some parcels were eliminated from this estimate for a variety of reasons. Some parcels identified were long narrow lots that likely could not meet property line setbacks for septic systems, all parcels below the 40-foot contour line were excluded as the lower lying areas of the Jacoby Creek Community Plan have a high-water table and are prone to flooding, and some parcels identified had significant portions over 30% slope. The golf course is similarly designated and zoned however these parcels were excluded from the calculations. Additionally, multiple parcels in the planning area currently meet minimum lot size requirements to allow for subdivisions. After accounting for these factors, approximately 76 parcels can be created based on a minimum parcel size requirement of 2 acres. Should the Board direct staff to process these amendments, a more in-depth review of specific areas and potential limitations would take place.
Creating new parcels creates new opportunities for development by right, including development of a primary residential unit, accessory dwelling unit (ADU), and junior accessory dwelling unit (JADU). Assuming development of three units per new parcel the proposed changes would result in an estimated maximum of 228 new housing units.
Should the Board direct staff to process the amendments to the General Plan, Jacoby Creek Plan and zoning, specific technical studies would be necessary to complete environmental review under the California Environmental Quality Act (CEQA). Specific studies include:
• A hydrogeologic investigation of groundwater availability and connectivity.
• A nitrate loading study of the potential of doubling the number of onsite wastewater treatment systems.
• Analysis of Vehicle Miles Traveled (VMT).
• Analysis of greenhouse gas emissions.
It is difficult to pin down the cost of proceeding with this. Initially additional records search is needed which will define where or if added testing is needed. To change the land use and zoning it will be critical to adequately evaluate potential impacts to groundwater resources. Once that is completed, an environmental document will need to be completed. Staff are anticipating a Mitigated Negative Declaration. The estimated cost of these studies and the staff time to process the amendments and CEQA review is approximately $300,000.
It is important to understand that this amount of effort will take time, which will result in the Parcel Map being continued until this is completed, which would be approximately 18 months.
SOURCE OF FUNDING:
None. Any future allocation to perform the work described in this report would likely need to come from the General Fund.
FINANCIAL IMPACT:
Staff estimate that the cost of performing the necessary studies and staff time needed to process the amendments to the General Plan, Jacoby Creek Plan and zoning would be approximately $300,000. Approximately $5,000 in staff time has been incurred in researching and preparing this information so far. The cost to perform these studies would likely need to come from the General Fund.
STAFFING IMPACT:
This assessment has been accomplished with existing staff in the Planning and Building Department and the Division of Environmental Health. Further targeted studies will be completed by qualified consulting firms as applicable. Processing these amendments can be done with existing staff provided that there is an appropriate funding source.
OTHER AGENCY INVOLVEMENT:
The preliminary assessment has been completed with input and feedback from the Division of Environmental Health
ALTERNATIVES TO STAFF RECOMMENDATIONS:
Board discretion.
ATTACHMENTS:
1. Urban Development Area and Residential Estates Map
2. Parcels Exceeding Minimum Map
3. Parcels Exceeding Minimum Public Water Map
PREVIOUS ACTION/REFERRAL:
Meeting of: September 9, 2025
File No.: 25-1051