Project Title:
2026 Urban Limit Line Renewal
County File Number:
GP25-0001
Applicant/Owner:
N/A
Project Location:
Countywide
California Environmental Quality Act (CEQA) Status:
Draft Environmental Impact Report pursuant to CEQA Guidelines Section 15153
Project Planner:
Will Nelson, Assistant Deputy Director, (925) 655-2898
Staff Recommendation:
Accept comments on the adequacy of the Contra Costa County 2045 General Plan and Climate Action and Adaptation Plan 2024 Update Draft EIR as the environmental document for the 2026 Urban Limit Line Renewal.
I. BACKGROUND
On November 6, 1990, Contra Costa County voters approved Measure C (Measure C-1990), the 65/35 Contra Costa County Land Preservation Plan Ordinance (the 65/35 Plan, County Ordinance Code Chapter 82-1), which established various mechanisms aimed at containing urban sprawl and protecting resources like agricultural land and scenic ridges and hillsides. 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 within the county may be designated for urban uses (residential, commercial, industrial, etc.) in the General Plans of the County and the 19 incorporated cities within the county, and at least 65 percent of the land must be designated for nonurban uses such as agriculture, open space, and parks. Meanwhile, the ULL establishes a regulatory boundary beyond which no land may be designated for urban land uses. Operating together, the 65/35 Standard and ULL limit the expanse of urban development in the county.
Measure C-1990 was set to expire on December 31, 2010. On November 7, 2006, county voters approved Measure L (Measure L-2006), which carried forward most elements of Measure C-1990 while adding requirements for a four-fifths vote of the Board of Supervisors and voter approval to expand the ULL by more than 30 acres, and periodic reviews of the ULL by the Board of Supervisors. Measure L-2006 also included a new ULL Map. The provisions of Measure L-2006 expire on December 31, 2026.
II. PROPOSED PROJECT
The proposed project is a 2026 ballot measure asking voters to amend the Land Use Element of the 2045 General Plan and the 65/35 Contra Costa Land Preservation Plan Ordinance to:
1. Extend the term of the 65/35 Plan and ULL for 25 years through December 31, 2051.
2. Modify the periodic ULL review requirements of the 65/35 Plan to require review of the ULL boundary concurrently with State-mandated Housing Element update cycles.
3. Modify the criteria and factors enumerated in the 65/35 Plan for determining whether land should be considered for placement outside the ULL.
4. Retain the requirement for voter approval to expand the ULL by more than 30 acres, except as specifically authorized in the 65/35 Plan, and approved by the voters in the ballot measure, namely:
a. The Board of Supervisors may, without subsequent voter approval, expand the ULL by any acreage within the boundaries of the Byron Airport Potential ULL Expansion Area, which will be illustrated on a new version of General Plan Land Use Element Figure LU-2, Urban Limit Line, after holding a public hearing at which the Board adopts a General Plan amendment for the expansion, by a four-fifths vote, after making each of the following findings based on substantial evidence in the record:
i. The expansion is necessary to further the economic viability of Byron Airport and attain the County's goals related to economic development.
ii. The expanded ULL area will accommodate uses directly linked to aeronautics, such as aviation research and development, aircraft manufacturing/assembly, and aeronautical schools/training facilities.
iii. The expanded ULL area will not accommodate residential development, logistics/distributions centers, lodging, or any other use not directly linked to aeronautics except for minor ancillary uses necessary to support the airport workforce.
iv. The expansion will not induce sprawl.
5. Retain in both the General Plan and County Ordinance Code the requirement that a four-fifths vote of the Board of Supervisors is necessary to place a measure on the election ballot to expand the ULL boundary by more than 30 acres through the year 2051.
6. Retain in both the General Plan and County Ordinance Code the existing procedure for expanding the County's ULL by 30 acres or fewer based on a four-fifths vote of the Board of Supervisors after holding a public hearing and making at least one of seven findings, as prescribed in both the General Plan and County Ordinance Code, based on substantial evidence in the record.
7. Modify the enumerated findings prescribed in both the General Plan and County Ordinance Code required for a change to the County's ULL under 30 acres to reflect the modified periodic ULL reviews and to make other non-substantive changes.
8. Retain the 65/35 standard for land preservation in Contra Costa County, whereby at least 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.
10. Approve a new ULL Map for the General Plan (Land Use Element Figure LU-2), 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.
11. Update administrative sections of the 65/35 Plan to correct outdated text and achieve consistency with the changes described in items 1-10 above.
The full draft ballot measure is included as Attachment A to the CEQA Initial Study for the project, which may be reviewed at https://envisioncontracosta2040.org/wp-content/uploads/2025/08/ULL_Initial-Study.pdf.
III. CEQA REVIEW
On November 5, 2024, the Board of Supervisors certified an environmental impact report for the Contra Costa County 2045 General Plan and Contra Costa County Climate Action and Adaptation Plan 2024 Update (the "GPEIR"). The GPEIR identifies 18 potentially significant impacts in the following environmental topic areas:
Agriculture and Forestry Resources
Mineral Resources
Air Quality
Noise
Biological Resources
Transportation
Cultural and Tribal Cultural Resources
Wildfire
Geology and Soils
Twelve of the 18 impacts were determined to be significant and unavoidable, meaning no feasible mitigations or alternatives are available to reduce the impacts to less-than-significant levels. The significant and unavoidable impacts are anticipated to occur in the topical areas italicized above.
Pursuant to CEQA Guidelines Section 15153, a lead agency may employ a single EIR to describe more than one project if the projects are "essentially the same in terms of environmental impact" and the circumstances of the projects are essentially the same. Pursuant to Section 15153, the County has prepared an Initial Study to determine whether the GPEIR may serve as the environmental document for the proposed 2026 ULL ballot measure. The Initial Study concluded that the criteria enumerated in Section 15153 have been satisfied and the GPEIR may be used as the CEQA environmental document.
IV. HEARING TO RECEIVE PUBLIC COMMENTS
The purpose of this hearing is to provide additional opportunity for the public to submit written or verbal comments on the adequacy of the GPEIR as the environmental document for the 2026 ballot measure. A 45-day public review and comment period for the GPEIR began on Monday, August 25, 2025. Written comments not submitted during this meeting must be submitted to the following address by 5:00 p.m. on Thursday, October 9, 2025:
Contra Costa County
Department of Conservation and Development
30 Muir Road
Martinez, CA 94553
Attn: Will Nelson
Written comments may also be submitted via email to will.nelson@dcd.cccounty.us or advanceplanning@dcd.cccounty.us.
County Zoning Administrator
September 15, 2025
GP25-0001
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