To: Board of Supervisors
From: John Kopchik, Director, Conservation and Development
Report Title: Update on 2026 Urban Limit Line Ballot Measure
☒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 and 65/35 Land Preservation Plan Ordinance and PROVIDE direction to staff.
FISCAL IMPACT:
No fiscal impact currently. Department of Conservation and Development (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 and 65/35 Land Preservation Plan Ordinance
On November 6, 1990, Contra Costa County voters approved Measure C, the 65/35 Contra Costa County Land Preservation Plan Ordinance (the “65/35 Plan”), which established 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 Urban Limit Line (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 regulatory boundary beyond which no urban land uses may be designated. Working in tandem, the 65/35 Standard and ULL limit the geographic extent of urban development across 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. The provisions of Measure L are in effect through December 31, 2026.
February 2025 Board of Supervisors Meeting
On February 25, 2025, DCD staff made a presentation to the Board of Supervisors on a potential 2026 ballot measure to extend the ULL and 65/35 Plan. Topics discussed were:
• Contents of a proposed ballot measure.
• Effects of a County ULL ballot measure on cities.
• The relationship between a ULL ballot measure and the County’s 2045 General Plan and Ordinance Code.
• The term/duration of the ballot measure.
• Periodic ULL reviews.
• The process and findings for adjusting the ULL.
• Potential adjustments to the ULL map.
• The proposed schedule.
These topics are revisited below. Staff is also providing additional information on the process for placing a measure on the ballot, results of public outreach since the February Board meeting, and the environmental review process.
Summary of Recommended Components of the 2026 ULL Ballot Measure
Staff recommends that the Board direct staff to prepare a ULL ballot measure that asks the voters of Contra Costa County to amend the Land Use Element of the 2045 General Plan and the 65/35 Contra Costa Land Preservation Plan Ordinance (County Ordinance Code Chapter 82-1) to:
1. Extend the term of the 65/35 Land Preservation Plan Ordinance and the County’s Urban Limit Line through December 31, 2051.
2. Modify the periodic ULL review requirements of the 65/35 Land Preservation Plan Ordinance to require review of the ULL boundary every eight (8) years for the purpose of aligning ULL reviews with Housing Element update cycles.
3. Modify the criteria and factors enumerated in the 65/35 Land Preservation Plan Ordinance for determining whether land should be considered for location outside the ULL to explicitly include undevelopable islands; lands with high or very high fire hazard risk; lands at risk of substantial inundation from flooding or sea level rise; lands with formal development restrictions such as certain easements or deeded development rights; and lands with inadequate urban infrastructure; and to make other non-substantive edits.
4. Retain, during the extended term of the 65/35 Land Preservation Plan Ordinance and the County’s ULL, the requirement for voter approval to expand the ULL by more than thirty (30) acres, except as specifically authorized in the 65/35 Land Preservation Plan Ordinance, and approved by the voters in the ballot measure, namely:
a) The Board of Supervisors may, without subsequent voter approval, expand the ULL by more than thirty (30) acres within the Byron Airport Expansion Area based on a 4/5 vote of the Board of Supervisors after holding a public hearing and making each of the following findings:
i. That the expansion is occurring within the boundaries of the Byron Airport Expansion Area shown on the official ULL map contained in the Contra Costa County 2045 General Plan Land Use Element.
ii. That the expansion is necessary to further the economic viability of Byron Airport and attain the County’s goals related to economic development.
iii. That the expanded ULL area will accommodate uses directly linked to aeronautics, such as aviation research and development, aircraft manufacturing, and pilot/crew training.
iv. That the expanded ULL area will not accommodate residential development, logistics/distributions centers, lodging, or any other type of development not directly associated with aeronautics except for minor ancillary uses necessary to support the airport workforce.
5. Retain in the General Plan and County Ordinance Code the requirement that a 4/5 vote of the Board of Supervisors is necessary to place a measure on the election ballot to expand the ULL boundary by more than thirty (30) acres through the year 2051.
6. Retain in the General Plan and County Ordinance Code the existing procedure for any change to the County’s ULL under thirty (30) acres based on a 4/5 vote of the Board of Supervisors after holding a public hearing and making at least one of seven findings, as prescribed in the General Plan and County Ordinance Code, based on substantial evidence in the record.
7. Modify the enumerated findings prescribed in the General Plan and County Ordinance Code required for a change to the County’s ULL to reflect a modified periodic ULL review, additional findings related to Byron Airport, and additional finding related to ULL contractions, and to make other non-substantive changes.
8. Retain the 65/35 standard for land preservation in Contra Costa County, whereby at least sixty-five (65) percent of the overall county land area will be retained for non-urban uses through the year 2051.
9. Retain the protections for the county’s prime agricultural land, specifically the area designated in the General Plan as the Agricultural Core by maintaining the 40-acre minimum parcel size and limiting uses to agricultural production or uses incidental to agricultural production.
10. Approve a new ULL Map for the General Plan (Figure LU-2 in the 2045 General Plan Land Use Element), which reflects the following changes:
a) Moves 3,487 acres with significant development restrictions, such as ownership by government agencies or encumbrance with conservation or agricultural easements, outside the ULL.
b) Moves 1,488 acres of buffer lands around subdivisions, cemeteries, and industrial facilities, outside the ULL.
c) Moves 4,368 acres with significant development constraints, such as high fire hazards, steep slopes, and flood hazards, outside the ULL.
d) Moves 873 acres outside the ULL and 923 acres inside the ULL to align the ULL with city limits.
e) Moves 847 acres outside the ULL and 421 acres inside the ULL to simplify and improve understanding of the ULL along the county’s shoreline.
f) Moves 130 acres occupied by existing development inside the ULL.
g) Moves 129 acres inside the ULL to eliminate fragmentation in areas where various city annexations have left pockets of land remaining outside the ULL.
Effects of County ULL Ballot Measure on Cities
In February, staff reported its conclusion, based on review of city resolutions adopting the ULL, that the County’s ULL ballot measure would have no impact on the ULLs adopted by the 19 cities in the county. Staff forwarded the ULL materials from the February 25 Board meeting to the cities, made presentations to the City of San Ramon Open Space Advisory Committee (March 17), Contra Costa Planning Directors (April 11), Public Managers Association (May 8), and Brentwood City Council (May 27). Staff also consulted with staff and/or elected officials from the cities proximate to proposed ULL changes, namely the cities of Antioch, Brentwood, Martinez, Oakley, Pinole, Pittsburg, Pleasant Hill, Richmond, San Ramon, and Walnut Creek. Correspondence has been received from the cities of Brentwood and Oakley (included in Attachment B). No information has been submitted contesting staff’s initial conclusion that the 2026 ULL ballot measure would have no effect on the cities’ ULLs.
Relationship Between the ULL Ballot Measure, 2045 General Plan, and County Ordinance Code
In February, staff provided an overview of how the previous ULL ballot measures amended the Land Use Element of the County General Plan and County Ordinance Code Chapter 82-1, along with the consequences of failing to adopt a new ULL ballot measure in 2026. Here, once staff has prepared the proposed ballot measure based on Board direction, the Board would act by resolution to approve the ballot measure, including complete General Plan and ordinance language and the new ULL Map as they would appear in the measure and voter pamphlet, and direct the County Clerk to conduct the election on the measure pursuant to the California Elections Code. If approved by the voters, the amendments to the General Plan, Ordinance Code, and ULL Map would go into effect. The Board, itself, would not adopt the amendments to the General Plan or Ordinance Code. The significance of this distinction is process related. General Plan and zoning code amendments require public notification and a County Planning Commission (CPC) hearing where the CPC makes a recommendation to the Board of Supervisors. Those requirements do not apply when the amendments are enacted through a ballot measure. The Board’s action will be to place the measure on the ballot, not to adopt the amendments to the General Plan and Ordinance Code.
Term/Duration of the Ballot Measure
In February, staff recommended a term of at least 25 years for the 2026 ULL ballot measure (Measures C and L each had 20-year terms). Staff also indicated that another option would be to make the 65/35 Plan and ULL permanent. Following discussion, the Board appeared to favor a 25-year term, with the ballot measure expiring in 2051. Staff will proceed with drafting a 25-year ballot measure unless otherwise directed by the Board.
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 2016 mid-term review, conducted in cooperation with the cities, demonstrated ample development capacity within the ULL through 2036. Furthermore, the County’s 2045 General Plan, adopted by the Board in November 2024, provides substantial development capacity in the unincorporated areas through its urban 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. Given the considerable development capacity known to exist within the ULL, in February, staff recommended that the 2026 ballot measure align ULL reviews with the State-mandated Housing Element update cycle, which requires a housing capacity analysis every eight years. Doing so would result in three ULL reviews over a 25-year term. Following discussion, the Board appeared to support the concept of aligning ULL reviews with the Housing Element cycle. Staff will proceed with drafting a ballot measure that aligns ULL reviews with the County’s Housing Element update cycle unless otherwise directed by the Board.
Process and Findings for Adjusting the ULL
The County processes proposals to adjust the ULL as General Plan Amendments (GPAs), making them subject to State and County statutes and policies governing such applications. Requests to expand the ULL are also subject to supplemental procedures specified in Measure L. Adoption of a ULL expansion of 30 or fewer acres requires a 4/5 vote of the Board of Supervisors (whereas other GPAs require a simple majority) after making one or more of seven findings enumerated in Measure L. Adoption of a ULL expansion exceeding 30 acres requires a 4/5 vote of the Board after making one or more of the seven findings, plus countywide voter approval. Staff notes that an expansion exceeding 30 acres has never occurred.
Below are the seven existing findings to change the ULL, each followed by staff’s rationale for how they may be revised in the future ballot measure:
1) 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.
Rationale for revising: Text could be streamlined and modernized. For example, “man-made” could be replaced with “human-made” consistent with the Board’s recently adopted policy on gender-specific pronouns in County documents.
2) 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.
Rationale for revising: Text could be streamlined and modernized. For example, “fair share of affordable or regional housing” could be replaced with “Regional Housing Needs Allocation (RHNA),” the accurate term for the housing that’s described. This finding could also be revised to incorporate the Board’s direction to align ULL reviews with the Housing Element cycle.
3) 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.
Rationale for revising: Intent could be clarified by specifying a preservation agreement must include interjurisdictional agreement on growth boundaries and a city affected the proposed ULL change must be a party.
4) A minor change to the ULL will more accurately reflect topographical characteristics or legal boundaries.
Rationale for revising: There is no pressing need to revise this finding.
5) 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 Airport, and either mitigate adverse aviation related environmental or community impacts attributable to Buchanan Field, or further the County’s aviation-related needs.
Rationale for revising: This finding could be replaced entirely depending on the Board’s final direction regarding adjustment of the ULL around Byron Airport. See the section above summarizing the recommended components of the ballot measure, including proposed findings for a Byon Airport expansion.
6) A change is required to conform to applicable California or federal law.
Rationale for revising: There is no apparent need to revise this finding.
7) 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.
Rationale for revising: This finding could be deleted entirely. Five-year cyclical reviews will not occur if ULL reviews are aligned with the Housing Element cycle. Alternatively, it may be useful to retain the portion of this finding that allows for the ULL to be changed based on availability of “new information” or “change in circumstances.” For example, if an area was placed outside the ULL because it was mapped as a High Fire Hazard Severity Zone, but the hazard severity was later downgraded, then it might be appropriate to adjust the ULL in that location.
Staff notes that Measure L (and therefore the General Plan and County Ordinance Code) does not expressly address the process for ULL contractions. The Measure L text broadly states that “changes” to the ULL require a 4/5 vote of the Board after making one or more of the seven findings, and although the findings also refer to “changes” to the ULL, the wording is suggestive of expansions and not contractions. Moreover, the requirement in Measure L for subsequent voter approval is specific to expansions of the ULL by more than 30 acres and does not refer to contractions. While the voter approval requirement does not apply to contractions, staff believes that clarifying this will benefit the public and decision-makers.
Staff recommends that the future ballot measure contain language addressing contractions. Specifically, staff recommends the ballot measure include language clarifying that contractions of any acreage may be approved only by a 4/5 vote of the Board after making an appropriate finding based on substantial evidence in the record. Appropriate findings may include that: (i) the contraction will more accurately reflect topographical characteristics or legal boundaries; (ii) the contraction is approved by a majority of cities that are party to a preservation agreement; (iii) based on a periodic review, new information is available or circumstances have changed warranting the contraction; (iv) the contraction would more accurately reflect hazards or an area’s protection/conservation status; (v) the contraction is required to conform to applicable California or federal law; or (vi) the contraction would limit urban sprawl or protect resources.
Potential Adjustment to the Urban Limit Line Map
In February, staff presented a comprehensive series of draft maps depicting potential ULL contractions and expansions for the Board’s consideration. Following review of public comments received since February and a re-examination of the maps, staff recommends several additional adjustments resulting in the following acreage changes:
|
|
February 2025 |
June 2025 |
Difference |
|
Contractions |
10,787 |
11,063 |
+276 |
|
Expansions |
1,634 |
1,603 |
-31 |
|
Net Acres of Contraction |
9,153 |
9,460 |
+307 |
|
Not included is the approximately 500-acre Byron Airport Study Area expansion described below. |
Exhibit A is an updated map series reflecting the additional ULL adjustments (all acreage changes in parentheses are relative to the February 2025 maps). The changes appear in Figures 2-8 and Tiles A, D, E, G, and K. Potential adjustments are categorized as follows (more detailed descriptions of these categories were provided in staff’s February 25 report to the Board):
ULL Contractions
a) Restricted Development, 3,487 acres (+254 acres). These contractions would move outside the ULL land with permanent development restrictions. This acreage increase results from staff’s identification of land encumbered by a scenic easement in the Tassajara Valley and transfer of a 25-acre parcel south of Antioch from the Constraints category because it is encumbered by a conservation easement.
b) Buffers, 1,488 acres (no change). These contractions would move outside the ULL land set aside as buffers around subdivisions, cemeteries, and industrial facilities (e.g., refineries and quarries).
c) Constraints, 4,368 acres (-25 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. The reason for this acreage decrease is described above.
d) Align with City Limits, 873 acres (-15 acres). These contractions move the ULL inward to align with the incorporated limits of several cities. This acreage decrease results from an unincorporated parcel adjacent to Pittsburg being part of a development proposal that includes annexation of the parcel to the city.
e) Shoreline Simplification, 847 acres (+62 acres). These contractions smooth out the ULL along the shoreline and place undevelopable islands in San Pablo Bay and the Delta outside the ULL. This acreage increase results from adjusting the ULL to exclude a sandbar and water in San Francisco Bay near the West County Landfill.
ULL Expansions
a) Existing Development, 130 acres (-1 acre). These expansions would bring inside the ULL certain properties already developed with homes, businesses, a sports facility, and a former fire station. This acreage decrease results from correcting an overlap with a proposed contraction off Camino Tassajara.
b) Improved Clarity, 129 acres (-30 acres). These expansions eliminate existing fragments or holes in the ULL that were created when land was annexed to cities, and new fragments that would be created by other recommended expansions and contractions. These expansions also eliminate instances where the ULL unnecessarily splits parcels. This acreage decrease results from staff proposing to leave more of the Stonegate HOA common area in Alamo outside the ULL.
c) Align with City Limits, 923 acres (no change). These expansions move the ULL outward to align with the incorporated limits of several cities.
d) Shoreline Simplification, 421 acres (no change). These expansions smooth out the ULL along the shoreline.
e) Byron Airport Study Area, approximately 500 acres (no change). This expansion involves land between the airport and Byron Highway and is the only expansion contemplated as a precursor to potential future development.
Staff reiterates that the recommended expansions do not approve new development. Moving land inside the ULL makes conversion to urban use a possibility if it hasn’t already occurred. Subsequent GPAs would be required to change non-urban land use designations to urban in support of more intense development. These GPAs could be adopted only if the Board found them to be consistent with the goals and policies of the General Plan, and after the required environmental review is conducted under the California Environmental Quality Act.
Byron Airport Study Area
In February, staff presented two options for expanding the ULL to the east/northeast of Byron Airport to advance the airport’s capacity as a job center and economic engine. The potential expansion area, approximately 500 acres, lies between the airport and Byron Highway and consists mainly of generally poor agricultural land; approximately 39 acres are developed with light industrial uses and a solar energy facility. The area is flat, within the State Route (SR) 239 corridor being planned by Caltrans and the Contra Costa Transportation Authority (CCTA), and not a conservation priority under the East Contra Costa County Habitat Conservation Plan/Natural Community Conservation Plan.
The first option is to include the expansion on the ULL map that will be part of the ballot measure. If the voters passed the measure, then the ULL expansion illustrated on the map would take effect immediately. The second option is for the ballot measure’s ULL map to show an area of maximum possible expansion with accompanying language authorizing the Board to move the ULL within and up to the boundary of that area in the future. Because expansion ultimately could exceed 30 acres, the ballot measure would indicate that its adoption by the voters satisfied the requirement for a countywide vote to adopt a ULL expansion exceeding 30 acres. The ballot measure would also include findings limiting uses within the expansion area to aeronautical uses that benefit from proximity to the airport, such as aviation research and development and aircraft manufacturing.
Staff indicated in February that the second option has advantages. First, the County has not been approached with a proposal for aviation development on the land in the expansion area, so there is no immediate pressure to move the ULL. Second, the SR 239 alignment has not been finalized and that could affect the ideal location of the ULL boundary. Finally, deferring ULL expansion until needed guards against real estate speculation. Staff recommends the second option and seeks Board direction to proceed with incorporating that option into the ballot measure.
Factors for Determining Whether Land is Inside or Outside the ULL
Measures L contains the “criteria and factors for determining whether land should be considered for location outside the ULL.” The criteria and factors, listed below, were added to the General Plan and County Ordinance Code through Measure L’s adoption:
a) Land which qualifies for rating as Class I and Class II in the Soil Conservation Service Land Use Capability Classification.
b) Open space, parks, and other recreation areas.
c) Lands with slopes in excess of 26 percent.
d) Wetlands.
e) Other areas not appropriate for urban growth because of physical unsuitability for development, unstable geological conditions, inadequate water availability, the lack of appropriate infrastructure, distance from existing development, likelihood of substantial environmental damage or substantial injury to fish or wildlife or their habitat, and other similar factors.
While criterion e) is broad and functions as a sort of “catch all,” staff nonetheless recommends updating these criteria to reflect contemporary considerations. Fire hazards and sea level rise, for example, are significantly greater concerns than when Measure L was drafted and should be called out explicitly. Staff recommends modifying the list of criteria and factors as follows:
a) Lands which qualify for rating as Class I and Class II in the Soil Conservation Service Land Use Capability Classification.
b) Lands designated as High or Very High Fire Hazard Severity Zones on maps published by the California Department of Forestry and Fire Protection.
c) Lands with slopes exceeding 26 percent.
d) Lands at risk from substantial inundation due to flooding or anticipated sea level rise.
e) Lands with formal development restrictions such as agricultural, conservation, or scenic easements or deeded development rights.
f) Open space, parks, and other recreation areas.
g) Wetlands and undevelopable islands.
h) Areas with inadequate water, sewer, and roadway infrastructure.
i) Other areas not appropriate for urban growth because of separation from existing development, unstable geologic conditions, likelihood of substantial environmental damage or substantial injury to fish or wildlife or their habitat, and other similar factors rendering the land physically unsuitable for intense development.
Outreach and Public Comment
In February the Board directed staff to conduct public outreach. Staff forwarded the materials from the February Board meeting to all 13 Municipal Advisory Councils (MACs) and presented to the Alamo, Bethel Island, Byron, East Richmond Heights, El Sobrante, Knightsen, and Pacheco MACs at their request. No formal comments were received from any MAC.
As indicated above, staff forwarded the materials from the February Board meeting to all 19 cities in the county, made presentations to city officials, and consulted with staff and/or elected officials from seven cities. Formal comments were received from the cities of Brentwood and Oakley indicating their support for the proposed ULL adjustments in the vicinity of their cities. No other formal comments from cities have been received.
Staff met with staff from the Delta Stewardship Council and CCTA. Neither agency submitted formal comments.
On May 14 the CPC conducted a study session on the ULL. The CPC took public testimony and did not recommend changes to the draft ULL maps presented to the Board in February.
Finally, staff is using the Envision Contra Costa website and mailing list, which has over 1,200 subscribers representing a wide range of interests, to inform the public of Board meetings and publication of documents related to the ballot measure.
Public Comments
Twenty-one letters and emails were received between February 25 and June 4 (all are included in Exhibit B for the Board’s consideration). This correspondence falls into two broad categories: general comments and requests related to specific ULL adjustments. General comments were submitted by:
|
Blake, Juliet |
Joffe, Marc |
City of Brentwood |
|
Bristow, Patricia |
Jordan, John |
City of Oakley |
|
Gonzelez, John |
Logue, Gretchen |
Contra Costa Water District |
|
Grover, Cheryll |
Nisen, Mike |
|
The above correspondence provides information, observations, opinions, and questions. Requests related to specific ULL adjustments were submitted by:
|
Allison, Charlotte |
Mathias, Erin |
Environmental Coalition |
|
Cort, Robert |
Moita Family (Moita) |
Save Mt. Diablo |
|
Hempfling, Karl |
Moita Family (Kennedy) |
|
|
Jensen, Carol |
Nijjar, Jasbir |
|
Summaries of the requests and staff responses are provided below.
• Charlotte Allison (letter submitted by Moita and Moita, LLP). Ms. Allison owns two parcels totaling approximately 18 acres in Byron. Both parcels currently are split by the ULL and staff has recommended moving them entirely inside the ULL. Ms. Allison supports inclusion of her property inside the ULL and requested that the County also include a GPA and rezoning of her property in the ballot measure to support future residential development.
Response: No parcels will have their General Plan land use designation or zoning changed by the ballot measure.
• Robert Cort (letter submitted by Moita and Moita, LLP). Mr. Cort owns the 201-acre Byron Hot Springs property north of Byron Airport. The western portion of the property, approximately 72 acres, is inside the ULL. In February staff recommended that this portion of the property be moved outside the ULL. Mr. Cort requests that it remain inside the ULL.
Response: Staff does not recommend retaining the western portion of the Byron Hot Springs property inside the ULL. The property is in a High Fire Hazard Severity Zone in the State Responsibility Area (SRA) as designated by CalFire. The 2045 General Plan discourages residential density increases in High Fire Hazard Severity Zones in the SRA (General Plan Health and Safety Element policy HS-P7.1) unless there is a compelling reason to allow them. Most of the property inside the ULL also lies within Byron Airport Safety Zones 2 and 3, which restrict development to the following maximums:
Safety Zone 2
Residential Density: 1 unit/10 acres maximum
Nonresidential Intensity: 40 people/acre sitewide average; 80 people/single acre
Safety Zone 3
Residential Density: 1 unit/5 acres maximum
Nonresidential Intensity: 70 people/acre sitewide average; 210 people/single acre
The Safety Zone limits on residential density are consistent with the General Plan’s Agricultural Lands land use designation, a non-urban designation that establishes a maximum density of 1 unit/10 acres. The Safety Zones do not preclude nonresidential development at urban intensities. However, urban services (water and sewer) to support such development are neither available nor planned in the area.
Finally, the area in question is an isolated ULL fragment. Between Byron Hot Springs and Byron Airport are conserved parcels that serve as a permanent conservation bank for special status species or as permanent habitat mitigation for impact associated with construction of the airport. These parcels prevent contiguous urban development from the airport to the portion of Byron Hot Springs that is inside the ULL, meaning any urban development occurring at the Byron Hot Springs property would be stand-alone and disconnected from other existing or planned urban uses. Separation from other developed areas is a justification for moving land outside the ULL.
• Karl Hempfling. Mr. Hempfling owns two parcels totaling approximately 3.8 acres off Briones Road in the Alhambra Valley area. Mr. Hempfling requested that they be moved inside the ULL.
Response: Staff does not recommend moving Mr. Hempfling’s parcels inside the ULL. Mr. Hempfling met briefly with staff and followed up with an email requesting inclusion of his parcels inside the ULL. Staff requested further explanation of the request and received no response. The parcels are already developed and located in a High Fire Hazard Severity Zone.
• Carol Jensen. Ms. Jensen requests that the ULL be moved east to include the previously developed portion of Byron Hot Springs, which includes the historic hotel.
Response: In staff’s opinion there is no need to move the ULL as Ms. Jensen requests. Policy 5 in the Byron Community Profile (within the General Plan Stronger Communities Element) states:
Encourage reuse of the previously developed portion of the Byron Hot Springs property in a way that is compatible with operations at Byron Airport, rehabilitates historic buildings, attracts regional tourists, and is not growth inducing.
The County has long acknowledged Byron Hot Springs as unique. This policy encourages restoration of the historic hotel and, because of the site’s uniqueness, could allow for uses that normally may not be permissible outside the ULL.
• Erin Mathias. Ms. Mathias requested that properties she owns on Sellers Avenue near Oakley and Camino Tassajara near San Ramon remain outside the ULL.
Response: Neither of Ms. Mathias’s properties was proposed to be moved inside the ULL on the February draft ULL maps. Both properties will remain outside the ULL.
• Moita Family (letters submitted by Moita and Moita, LLP and Dana Kennedy, Miller Starr Regalia). The Moita family owns approximately 164 acres off Marsh Creek Road along the eastern limit of the City of Clayton. Most of the property, approximately 151 acres, is outside the ULL. Approximately 54 acres are within Clayton’s Sphere of Influence. In February staff recommended that the remaining portion of the property that is inside the ULL, approximately 13 acres, be moved outside the ULL. The Moita Family requests that the family’s entire property, approximately 164 acres, be moved inside the ULL to support development of up to 103 large-lot single-family homes.
Response: Staff does not recommend retaining the Moita property inside the ULL. The residential development the letters reference is envisioned in the Marsh Creek Road Specific Plan adopted by the City of Clayton in 1995. Specific Plan policy IM-8 states, “The City shall petition LAFCO to amend its Sphere of Influence to include the Specific Plan area shown in Figure 6,” and policy IM-9 states, “All development under this Specific Plan shall occur under the jurisdiction of the City of Clayton.” Most of the Moita property is outside the city’s ULL (the city adopted the County’s 2006 ULL, so the portion of the property the County is proposing to move outside its ULL is also within the city’s ULL). To staff’s knowledge, the city has never attempted to bring the Moita property entirely inside its ULL or Sphere of Influence. Conversely, Figure 3 of the Growth Management Element of the city’s General Plan illustrates areas proposed for removal from the city’s Sphere of Influence, including the portion of the Moita property outside the ULL. Specific Plan policy IM-12 recommends that the Specific Plan policies be applied in the unincorporated county, but the County’s 2045 General Plan is the controlling land use policy document.
The County General Plan addresses the types of development constraints that exist on the Moita property. The entire property is in a Very High Fire Hazard Severity Zone in the SRA. General Plan policy HS-P7.1 instructs County decision-makers to deny entitlements for projects creating additional residential units (i.e., units not allowed by-right) in Very High Fire Hazard Severity Zones in the SRA. Any application for a GPA, rezoning, subdivision, or development plan to increase residential density therefore should be denied. General Plan policy HS-P11.5 prohibits development on slopes of 26 percent or greater (with exceptions for infrastructure projects and development of existing legal lots where no feasible alternatives exist) and discourages development on slopes exceeding 15 percent. The County’s geographic information system slope percentage map, which was created from source data obtained using Light Detection and Ranging (LiDAR) technology, shows that approximately 77 percent of the Moita property exceeds 26 percent slope and approximately 17 percent of the remaining acreage has a slope of 15 percent or greater. Policy HS-P11.5 therefore is applicable to approximately 94 percent of the property. Finally, the property is rich in biological resources that the General Plan aims to protect through policies in the Conservation, Open Space, and Working Lands Element. The combination of fire hazard, slope, and biological sensitivity justify the entire property’s exclusion from the ULL to preclude development at urban intensities.
• Jasbir Naijjar: Mr. Nijjar owns two parcels totaling approximately 353.7 acres along State Route 4 south of Discovery Bay. Mr. Nijjar requests that his entire property be moved inside the ULL to allow for development “as primarily an industrial job center.” Mr. Nijjar submitted a draft agreement outlining various contributions to the County, EBRPD, and charitable causes in exchange for moving his land inside the ULL.
Response: Staff does not recommend moving Mr. Nijjar’s parcels inside the ULL. Sufficient land exists inside the ULL in East County to accommodate anticipated job growth.
• Environmental Coalition (consisting of Greenbelt Alliance, 350 Contra Costa Action, Contra Costa County Climate Leaders, and other organizations and individuals). The Environmental Coalition’s letter generally supports the draft ULL adjustments staff proposed in February. Areas of concern are Byron Airport and the Tassajara Parks project. The letter in part states the following regarding Byron Airport:
We understand the value of long-term economic development but want to ensure that there is no way the Byron Airport area could trigger sprawl. The region surrounding the Byron Airport, especially with discussions around economic zones, poses a major risk of sprawl. Any infrastructure or policy changes in this area must explicitly rule out housing, distribution centers and tourism under the guise of “economic opportunity.” We implore the county to be extremely specific around what is defined by “airport use” so as to avoid cargo distribution centers and the like.
Regarding the Tassajara Parks Project, the letter in part states:
For Tassajara Parks, we believe that the line has been mistakenly drawn to indicate that this project is moving forward, however since the court determined that the movement of the line is conditional on the full approval of the Tassajara Parks Project, the Preservation Agreement, and the dedication of certain acreage on the protected side of the line, to East Bay Parks - none of which has occurred. The County has yet to legally establish all these necessary criteria for line movement, therefore the ULL should remain in its original position. Please see the letter in attachment A for more information.
By “original position,” the Environmental Coalition is referring to the ULL location prior to the Tassajara Parks approval in 2021. Attachment A to the Coalition’s letter is a letter authored by Jessica Blome of Greenfire Law, PC, providing a more detailed explanation of the Coalition’s position. Ms. Blome’s letter concludes with:
The court’s final judgment did not expand the ULL. Staff’s desire to now expand the ULL to accommodate the acreage desired for the Tassajara Parks Project during the 2026 voter-approval process must be understood for what it is-an effort to expand the ULL by voter-approval so that the developer may build Tassajara Parks. But the Tassajara Parks Project may not move forward; indeed, the developer may elect not to proceed with the Project, the Board of Supervisors may vote it down for a variety of reasons, and the East Bay Municipal District may hold-fast to its prior decision to decline water service to the Project. Voters must demand that the County transparently tell the public that the impact of its 2026 ULL maps includes preemptive, unnecessary expansion of the ULL to accommodate the conversion of cherished open space into a residential subdivision. The public deserves this critical information, so they can make informed decisions about whether to support staff’s 2026 maps. Moreover, greenspace advocates must demand that the County require the Tassajara Agreement in exchange for Tassajara Parks Project approval, even if voters approve the 2026 maps with the Tassajara Parks acreage expansion. If voters approve the expansion as a part of the 2026 ULL vote without this commitment, the County could approve the Tassajara Parks Project without the Tassajara Agreement.
Response: Regarding Byron Airport, staff agrees that expanding the ULL in the vicinity of the airport should not lead to sprawl. Staff has drafted findings that may address the Environmental Coalition’s concerns (see the summary of recommended components of the ballot measure).
Regarding the Tassajara Parks Project, the Superior Court ordered the County to set aside the project approvals and decertify the environmental impact report for the project. However, the Court found that the 30-acre modification to the ULL and the Tassajara Agreement were severable from the remainder of the Tassajara Parks Project and left those County approvals in place. Specifically, the County was ordered to set aside and vacate all Tassajara Parks Project-related approvals, “with the exception of (a) the expansion of the 30-acre expansion of the Urban Limit Line (ULL) under Contra Costa County Code section 82-1 .018(a)(3), to the extent that approval of the expansion of the ULL merely extends the ULL by 30 acres not limited by or to the Project's residential development of 125 homes under the Development Agreement, and (b) the approval of the Tassajara Agreement related to the 30-acre expansion of the ULL under CCC Code section 82-1.018(a)(3).” The County’s action in response to the Court order rescinded the Project approvals (i.e., the GPA, rezoning, subdivision, development plan, and development agreement), but did not rescind the 30-acre modification to the ULL. Documentation of this County action was submitted to and accepted by the Court. The ULL, as illustrated in detail on Tile D in Attachment A, is in the correct location.
• Save Mt. Diablo (SMD). SMD’s letter generally supports the draft ULL adjustments staff proposed in February. Areas of concern are Byron Airport and the Tassajara Parks Project. The letter in part states the following regarding Byron Airport:
As long as the possibility of residential development is excluded, and care is taken that development in this area is consistent with the County General Plan and Climate Action Plan, the County staff proposal for the area east of Byron Airport is reasonable.
We are obviously supportive of adjusting the ULL to exclude sensitive open space lands to the north, west and south of the airport.
Regarding the Tassajara Parks Project, the letter in part states:
The County Board of Supervisors fulfilled all requirements, including the creation of the Tassajara Valley Agricultural Preserve, to adjust the ULL by 30-acres to accommodate the development footprint of the project. While the Board also separately approved the Tassajara Parks project itself in the summer of 2021, a lawsuit was filed against the project approval, and a subsequent ruling in 2023 vacated that approval pending further analysis of water supply issues.
In so much as these actions are relevant to the current County ULL renewal, we agree with County staff that the 30-acre adjustment made several years ago stands and the current County ULL includes what was the planned Tassajara Parks development footprint within it. We are pleased that the Tassajara Valley now and in the future has a double layer of protection: the ULL (assuming it is renewed) and the Agricultural Preserve.
Response: See responses to the Environmental Coalition letter above.
California Environmental Quality Act (CEQA) Compliance
The Board’s action to approve a ULL ballot measure and placing the measure on an election ballot is a project subject to the requirements of CEQA. Staff estimates completion of the CEQA review within approximately 60-90 days following direction from the Board on how to proceed with the various ballot measure components that remain unresolved.
Project Schedule
The 2026 Primary Election is scheduled for June 2, 2026, with the General Election scheduled for November 3, 2026. In February, the Board indicated its intent for the ULL ballot measure to appear on the 2026 Primary Election ballot and directed DCD to make every effort to bring the ballot measure back to the Board for final action in 2025. The remaining process is as follows:
• July/August 2025: Publish CEQA document for a 45-day public review period.
• October/November 2025: Board to consider approving final ballot measure language, directing the County Clerk place the measure on the 2026 Primary Election ballot, and taking related actions including actions to comply with the California Environmental Quality Act.
Pursuant to the California Elections Code, the Board must submit the ballot measure to the County Clerk no fewer than 88 days prior to the June 2026 Primary Election, making Friday, March 6, 2026, the deadline for submission of the measure.
CONSEQUENCE OF NEGATIVE ACTION:
Staff would not receive direction from the Board on how to proceed with preparation of a 2026 ULL ballot measure.