To: Board of Supervisors
From: John Kopchik, Director, Conservation and Development
Report Title: Report on 2026 Ballot Measure to Renew the County Urban Limit Line
☒Recommendation of the County Administrator ☐ Recommendation of Board Committee
RECOMMENDATIONS:
ACCEPT a report from the Conservation and Development Director on a 2026 ballot measure to renew the County’s Urban Limit Line (ULL) and PROVIDE direction to staff.
FISCAL IMPACT:
No fiscal impact at this time. DCD staff time associated with preparing the ballot measure is covered entirely by the Land Development Fund.
BACKGROUND:
Brief History of the Urban Limit Line
On November 6, 1990, Contra Costa County voters approved Measure C, the 65/35 Contra Costa County Land Preservation Plan (the “65/35 Plan”), which established various mechanisms aimed at containing urban sprawl and protecting resources like agricultural land and scenic ridges. The most significant and impactful of these mechanisms are the 65/35 Land Preservation Standard (the “65/35 Standard”) and ULL. Pursuant to the 65/35 Standard, no more than 35 percent of the land in the county may be designated for urban uses (residential, commercial, industrial, etc.) in the General Plans of the County and 19 cities, and at least 65 percent must be designated for agriculture, open space, parks, and other non-urban uses. Meanwhile, the ULL establishes a boundary beyond which no urban land uses may be designated. Working together, the 65/35 Standard and ULL limit the geographic extent of urban development in the county.
Measure C was set to expire on December 31, 2010. On November 7, 2006, county voters approved Measure L, which carried forward most of the elements of Measure C while adding provisions for periodic ULL review and establishing different processes for expanding the ULL by 30 acres or fewer and more than 30 acres. Measure L is in effect through December 31, 2026.
California Environmental Quality Act (CEQA) Compliance
The ULL ballot measure is a project subject to the requirements of CEQA. Staff will determine the appropriate CEQA document when the project description is further developed and stable.
Effects of County ULL Ballot Measure on Cities
In November 2004, county voters approved Measure J, an extension of the Contra Costa Transportation Authority (CCTA) half-cent transportation sales tax originally approved through passage of Measure C in 1988 (this is not the same Measure C that created the ULL). A component of Measure J, the Growth Management Program (GMP), required the County and 19 cities to adopt and continuously comply with a mutually agreed-upon ULL or their own voter approved ULL to receive their shares of Measure J Local Street Maintenance and Improvement Funds (also known as “return to source funds”) and be eligible to receive Measure J Transportation for Livable Community Funds. The effort to create a mutually agreed-upon ULL failed. Following readoption of the County ULL in 2006, 16 of the 19 cities adopted the County’s ULL to comply with Measure J. Pittsburg, Antioch, and San Ramon adopted their own ULL (which San Ramon refers to as the Urban Growth Boundary [UGB]).
Staff reviewed the ULL adoption resolutions for the cities that adopted the County ULL. Each resolution explicitly states that the ULL adopted by the voters through Measure L is the ULL the city is adopting. Each city also adopted procedures for adjusting the ULL consistent with CCTA’s “Principles of Agreement for Establishing the Urban Limit Line,” with some adding provisions to address local issues. Nothing in any of the cities’ resolutions suggests that their ULLs could be affected by future actions of the County, such as a subsequent ULL ballot measure. Staff concludes that the 2026 ULL ballot measure would not affect the cities’ ULLs.
ULL Issues for Discussion
Relationship between ULL Ballot Measure, General Plan, and Ordinance Code
Measure C amended the General Plan Land Use Element and Ordinance Code, specifically the Zoning Code (Title 8), to establish the 65/35 Plan and ULL. Specific text was added to both documents and the voter-approved ULL map was added to the General Plan. Measure L modified the ULL map and amended the text of the General Plan and Zoning Code to extend the term of the 65/35 Plan and add procedures related to expansion and review of the ULL. The 2026 ballot measure would likely contain similar amendments to both documents.
The provisions of Measure L set to expire at the end of 2026 include the term of the 65/35 Plan and most procedures for expanding and periodically reviewing the ULL, but not the ULL itself. Were the provisions of Measure L to expire without a replacement voter-approved measure, then the 65/35 Plan and those procedures for expanding and reviewing the ULL would no longer be in effect, but the ULL would remain as part of the General Plan. The 65/35 Plan’s prohibition on designating land for urban uses outside the ULL would sunset, but General Plan policy LU-P2.3 provides a backstop by limiting development outside the ULL to non-urban uses. Absent Measure L’s requirement for a 4/5 supermajority vote to expand the ULL, the Board could expand it through the standard process to adopt a General Plan amendment (GPA), which requires a simple majority vote.
The Land Use Element and Growth Management Element of the 2045 General Plan each contain policies stating that a voter-approved ULL will be maintained. The Growth Management Element is consistent with the Measure J GMP. Failure to maintain a voter-approved ULL would cause the Growth Management Element to become inconsistent with the GMP and jeopardize the County’s “return to source” road maintenance funds, which are about $2 million annually.
Term
The Board has discretion to set the term of any extension to the ULL and 65/35 Plan when it approves the language for the ballot measure. Measures C and L each had 20-year expirations. Staff recommends a term of at least 25 years. A 20-year term, ending in 2046, would fall between the horizon year of the 2045 General Plan and the 8th Cycle Housing Element in 2047. These planning projects, a General Plan update, Housing Element update, and ULL renewal, are each multi-year efforts that require significant staff time and resources. This should be a consideration when determining the term, if any, for inclusion in the ballot measure. The Board also could consider making the ULL permanent.
Periodic ULL Reviews
Measure L contains two provisions for reviewing the ULL: optional 5-year reviews and a mandatory mid-term (year 2016) review. The purpose of the mid-term review was to determine whether any changes to the boundary of the ULL were warranted, “based on facts and circumstances resulting from the County’s participation with the cities in a comprehensive review of the availability of land in Contra Costa County sufficient to satisfy housing and jobs needs for 20 years thereafter.”
For several reasons, staff recommends against including periodic review requirements in the ballot measure. First, the 2016 mid-term review, conducted in cooperation with the cities, demonstrated substantial development capacity within the ULL through 2036. “Higher density” and “lower density” development scenarios were analyzed and staff determined that inside the ULL there was capacity for 67,400 to 110,800 residential units and 172,000 to 190,700 jobs. Second, the County’s 2045 General Plan, adopted by the Board in November 2024, provides substantial development capacity in the unincorporated areas through its land use designations. The General Plan EIR analyzed the impacts of developing 23,200 residential units, 1.2 million square feet of commercial space, and 5 million square feet of industrial space on vacant and underutilized land inside the ULL through the General Plan’s 2045 horizon year. Finally, every jurisdiction in California is required to update the Housing Element of its General Plan every eight years. A significant component of the Housing Element update is the housing sites inventory, which demonstrates each jurisdiction’s capacity to accommodate its Regional Housing Needs Allocation (RHNA). The California Department of Housing and Community Development will not certify a Housing Element with an inadequate sites inventory. Thus, the County and each of the 19 cities will complete three housing capacity analyses over the course of a 25-year ULL extension. Should the Board determine that periodic reviews of the ULL are warranted, then staff recommends such reviews be linked to Housing Element cycles for efficiency and that consideration be given to examining capacity to accommodate jobs.
Process and Findings for Adjusting the ULL
The County processes requests to adjust the ULL as GPAs. They are therefore subject to State and County regulations and policies governing such applications. Requests to expand the ULL are also subject to additional procedures contained in Measure L. ULL expansions of 30 or fewer acres require a 4/5 vote of the Board of Supervisors after making at least one of the following findings:
(a) A natural or man-made disaster or public emergency has occurred which warrants the provision of housing and/or other community needs within land located outside the ULL.
(b) An objective study has determined that the ULL is preventing the County from providing its fair share of affordable housing or regional housing as required by State law, and the Board of Supervisors finds that a change to the ULL is necessary and the only feasible means to enable the County to meet these requirements of State law.
(c) A majority of the cities that are party to a preservation agreement and the County have approved a change to the ULL affecting all or any portion of the land covered by the preservation agreement.
(d) A minor change to the ULL will more accurately reflect topographical characteristics or legal boundaries.
(e) An objective study has determined that a change to the ULL is necessary or desirable to further the economic viability of the East Contra Costa County (Byron) Airport, and either mitigate adverse aviation related environmental or community impacts attributable to Buchanan Field, or further the County’s aviation-related needs.
(f) A change is required to conform to applicable California or federal law.
(g) A five-year cyclical review of the ULL has determined, based on the criteria and factors for establishing the ULL set forth above, that new information is available (from city or County growth management studies or otherwise) or circumstances have changed, warranting a change to the ULL.
ULL expansions exceeding 30 acres must be approved by a 4/5 vote of the Board after making at least one of these findings, then also receive countywide voter approval. This has never occurred.
Adjustments to the ULL are rare; it has been moved only six times (1993, 1996, 2000, 2005, 2009, and 2021) since inception in 1990. Only once has it been moved as part of a private development application. Staff is not recommending specific changes to the ULL procedures or findings at this time.
Urban Limit Line Map
General Plan Land Use Element Figure LU-2, Urban Limit Line, is the official ULL map approved by the voters in 2006, as amended in 2009 and 2021. Exhibit A includes Figure LU-2 and a series of maps depicting potential ULL adjustments for the Board’s consideration. These adjustments constitute 10,787 acres of ULL contraction and 1,634 acres of ULL expansion, for a net contraction of 9,153 acres. These numbers do not include the approximately 500-acre Byron Airport Study Area expansion discussed below. Potential adjustments are categorized as follows:
Contractions
a) Restricted Development, 3,233 acres. These contractions would move outside the ULL land with permanent development restrictions. These restrictions include ownership by government agencies such as the East Bay Regional Park District and County Flood Control District; scenic, conservation, and agricultural easements; and grant deeds of development rights or similar instruments in favor of the County or other government entities. Most of this acreage is already designated Resource Conservation (RC), Parks and Recreation (PR), or Public and Semi-Public (PS) in the General Plan. These designations are non-urban and drastically limit development potential. The remaining acreage is designated Agricultural Lands (AL), which is also non-urban.
b) Buffers, 1,488 acres. These contractions would move outside the ULL land set aside as buffers around subdivisions, cemeteries, and industrial facilities (e.g., refineries and quarries). Nearly all this acreage is already designated RC in the General Plan. A small amount is designated AL.
c) Constraints, 4,393 acres. These contractions move outside the ULL land with development constraints such as steep slopes, high or very high fire hazards, flood hazards, high quality agricultural soil, access issues/isolation, or lack of access to utilities. These lands are inappropriate for urban development. All this acreage has a non-urban land use designation in the General Plan except for approximately 20.5 acres in Diablo and 1.1 acres in Byron designated for residential development. If those 21.6 acres were moved outside the ULL, then DCD would process a GPA in the future to change the land use designation to one that is non-urban, likely AL. To comply with the requirements of Senate Bill 330, that GPA would also increase density elsewhere to ensure no net loss of residential capacity.
d) Align with City Limits, 888 acres. These contractions move the ULL inward to align with the incorporated limits of San Ramon, Pittsburg, and Antioch, the cities that adopted their own ULL or equivalent Urban Growth Boundary instead of adopting the County’s 2006 ULL. All land shown to be moved outside the ULL has a non-urban General Plan land use designation.
e) Shoreline Simplification, 785 acres. These contractions smooth out the ULL along the shoreline and place undevelopable islands in San Pablo Bay and the Delta outside the ULL.
Expansions
a) Existing Development, 131 acres. These expansions would bring inside the ULL certain properties occupied by homes, businesses, a sports facility, and a former fire station. Some of these properties already have an urban General Plan land use designation despite being outside the ULL.
b) Improved Clarity, 159 acres. These expansions eliminate existing islands or holes in the ULL that were created when land was annexed to cities, and new islands that would be created by other recommended expansions and contractions. They also eliminate instances where the ULL unnecessarily splits parcels. Approximately 82 of these acres are owned and permanently protected by the National Park Service and East Bay Regional Park District. The remaining 77 acres are designated AL or RC in the General Plan. Most of this acreage has no urban development potential.
c) Byron Airport Study Area, approximately 500 acres. This expansion involves land between the airport and Byron Highway and is the only expansion contemplated as a precursor to potential future development.
d) Align with City Limits, 923 acres. These expansions move the ULL outward to align with city limits. Approximately 823 of these acres are within San Ramon city limits. These expansions have no regulatory effect on the County because they are within cities.
e) Shoreline Simplification, 421 acres. These expansions smooth out the ULL along the shoreline. Approximately 387 acres are within cities and include water adjacent to existing ports and marinas. ULL changes within the cities have no regulatory effect on the County. The remaining 34 acres are in Rodeo and unincorporated Antioch and include water adjacent to existing marinas. These areas have a Water land use designation in the General Plan. The Water designation allows shipping terminals, marinas, docks, and other marine-oriented uses and may exist inside and outside the ULL. Moving these areas inside the ULL is therefore inconsequential from a regulatory standpoint.
The potential expansions do not approve new development. Subsequent GPAs would be required to change non-urban land use designations to urban in support of more intense land uses. Such GPAs could be adopted only if they were consistent with goals and policies of the General Plan.
Byron Airport Study Area
The County owns and operates two general aviation airports, Buchanan Field Airport in Concord and Byron Airport south of Byron. The airports are self-funded and generate revenue for the County’s General Fund from leases, licenses, aircraft tax, sales tax, and other sources related to activities on airport property. While Byron Airport embodies a significant investment of public resources, it has historically operated at a deficit. The airport’s potential as a job center and economic engine is limited by scarcity of developable land on and near the airport property and inadequate road and utility infrastructure at the airport and in the vicinity. More development not only equates to more revenue, but private development projects typically construct or improve infrastructure. Adequate acreage should therefore be available for projects large enough to absorb the cost of installing the necessary infrastructure.
The ULL around Byron Airport is a nebulous form that was initially adopted several years before the airport opened. Today it poorly reflects actual land use and development potential around the airport. About 75 percent of the non-airport land surrounding the airport and within the ULL is owned by the County or East Bay Regional Park District and permanently protected. The remaining 25 percent is under private ownership and designated AL in the General Plan, which does not allow urban development. Urban services such as water and sewer are unavailable.
While the ULL around the airport has never been moved, the possibility of an adjustment has been contemplated since 1990, as evidenced by the finding to expand the ULL that relates specifically to the economic viability of Byron Airport and furtherance of the County’s aviation-related needs. The logical location for a ULL expansion is to the east and northeast, between the airport and Byron Highway, where several hundred acres of generally poor agricultural land remain mostly undeveloped. This area is flat, not a conservation priority under the East Contra Costa County Habitat Conservation Plan/Natural Community Conservation Plan, and within the State Route 239 corridor being planned by CCTA.
Staff sees two practical options for expanding the ULL to the east/northeast of the airport. The first is to include the expansion on the ULL map presented to the voters as part of the ballot measure. If the voters approved the ballot measure, then the ULL change, as shown on the map, would take effect immediately. The second option is for the ULL map included in the ballot measure to show a maximum extent of potential expansion with accompanying language authorizing the Board to move the ULL within and up to the boundary of that area in the future. Because such expansion would almost certainly exceed 30 acres, the ballot measure would make clear that its adoption by the voters satisfied the requirement for a countywide vote for a ULL expansion exceeding 30 acres. It may also be desirable for the ballot measure to explain the purpose of the expansion, which would be to facilitate development of aviation-related uses that depend upon proximity to the airport, and to limit future urban use to just these aviation-related uses. Both expansion options would include contracting the ULL by significantly greater acreage on the airport’s north, west, and south sides.
The second option is preferable in staff’s opinion. The County has not been approached with a proposal for aviation-related development on the land east/northeast of the airport, so there is no immediate need to move the ULL. The alignment of the State Route 239 right-of-way also has not been finalized and that could affect the ideal location of the ULL boundary. Additionally, deferring a ULL expansion until needed guards against real estate speculation.
Outreach
If so directed by the Board, staff proposes to conduct public outreach regarding the ULL renewal concepts discussed in this report. Proposed outreach includes at least one presentation to the County Planning Commission (CPC), consultation with the 19 cities in the county, and distribution of materials to the Municipal Advisory Councils (MACs). Staff would make presentations to MACs upon request. Staff also plans to utilize the Envision Contra Costa website and mailing list, which has over 1,200 subscribers representing a wide range of interests.
Proposed Schedule
The 2026 Primary Election will be held on June 2, 2026, and the General Election will be held on November 3, 2026. The ULL measure can be placed on either ballot, but staff recommends placing it on the Primary Election ballot in June 2026. The following outlines the steps necessary to place the measure on the Primary Election ballot:
• March-May 2025: Staff seeks feedback from the public, cities, MACs, and CPC.
• June/July 2025: Board meeting where staff reports on feedback received and presents draft ballot measure. Board provides further guidance to staff to refine the proposal, consider any environmental impacts, and return no later than February 2026 with final draft version of ballot measure and CEQA document for consideration by the Board.
• February 2026 (sooner, if possible): Board hearing to consider placing ULL measure on ballot for Primary Election.
This schedule includes conservative timeframes; the process ideally would be completed by the end of 2025.
CONSEQUENCE OF NEGATIVE ACTION:
Staff would not receive direction on how to proceed with preparation of a 2026 ULL ballot measure.