CONTRA COSTA COUNTY, CA (Apr. 29, 2025) — Have you ever gone cherry or peach picking in Brentwood? Or admired the beautiful green hills surrounding the Diablo Valley? These landscapes and historic farms are protected through the Contra Costa County Urban Limit Line (ULL).

Measure C, adopted by county voters in 1990, created the ULL to prevent sprawl and preserve open space by establishing a boundary beyond which no urban land uses – residential, commercial or industrial – can be planned. It helps focus growth within existing communities, where infrastructure and services are already available, while preserving open space and natural areas.

The county ULL applies to the unincorporated areas; each city has adopted its own ULL. The plans play a key role in enforcing the 65/35 Land Preservation Standard, also created in 1990, which ensures that no more than 35% of Contra Costa County is designated for urban use. The remaining 65% is reserved for non-urban uses such as agriculture, parks, conservation and water resources.

In 2006, voters extended the county ULL until Dec. 31, 2026. Now, a new measure is needed to maintain its protections. On Feb. 25, 2025, the Board of Supervisors accepted a report on the ULL from the county’s Department of Conservation and Development (DCD) and took the first steps in preparing a 2026 ballot measure for ULL renewal.

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The board directed DCD to conduct public outreach, indicated that the new ballot measure should likely extend the ULL for 25 years (until 2051) and explored the possibility of reviewing the ULL every eight years in conjunction with updating the Housing Element of the General Plan.

Adjustments to the ULL are rare – it has been moved only six times since its inception in 1990. The DCD report included 50 maps showing proposed ULL adjustments that move restricted development areas, protected open spaces and areas with significant development constraints outside the line as well as simplifying the ULL along shorelines. The adjustments align the county ULL with the boundaries of cities that adopted their own urban limit lines and with preexisting developments and parcel lines. The adjustments also eliminate isolated “islands” of land outside the ULL that are ­surrounded by cities and unincorporated land inside the ULL. As currently proposed, about 9,150 net acres would move outside the ULL.

DCD is gathering public input, and your feedback is essential. Please visit https://envisioncontracosta2040.org to learn about upcoming events and view detailed information about the ULL. Share your comments by 5 p.m. June 2, 2025, at advanceplanning@dcd.cccounty.us.

Comments will be addressed in a follow-up report to the Board of Supervisors. DCD anticipates that by the end of the year, the Board of Supervisors will vote to place the ULL renewal measure on the ballot for the June 2, 2026, Primary ­Election.

By continuing the ULL, Contra Costa County can preserve open space and encourage smart growth in accordance with the General Plan.

Ken Carlson is Contra Costa County District IV supervisor. Email questions or comments to SupervisorCarlson@bos.cccounty.us or call his office at 925-655-2350.