Local zoning · Contra Costa County

Contra Costa County — Overlay Districts

Overlay Districts under the Contra Costa County local zoning and planning code, with the controlling citations.

Quick answer

In unincorporated Contra Costa County, the -CE Cannabis Exclusion overlay applies in 9 communities and governs over base zoning on conflicts (§ 84-86.204, § 84-86.206). All underlying uses remain permitted except as limited by § 84-86.212 (§ 84-86.210). Where any district line (including an overlay) splits a lot, the least-restrictive district’s standards extend 30 ft into the other side (§ 82-10.006).

Last reviewed: July 25, 2026 · AI-generated analysis · General information, not legal advice · details

Compiled from Contra Costa County's adopted code with AI research tools and grounded in the sources cited below. Verify with Contra Costa County planning staff before relying on it.

Overview

In unincorporated areas of Contra Costa County, “overlay” or “combining” districts layer additional rules on top of a base zone. Overlays are mapped on the County’s official zoning map and, where stated, can override underlying zoning standards. The County’s adopted overlays confirmed in the source materials are the Cannabis Exclusion (-CE) combining district and a Special District SD-1 that can be combined with certain zones.

If a district boundary splits a lot in unincorporated areas, the standards of the least-restrictive side extend 30 feet into the other side (§ 82-10.006). This applies to district lines shown on the County zoning map and can materially affect what you can do near an overlay edge.

How overlays are mapped and interpreted

The County’s official zoning map controls where districts (including any combining districts) apply; the map is incorporated into the zoning ordinance (§ 84-2.002(a)–(c)). If a boundary is unclear, the code provides tie-breakers (centerline of street, property line, map scale) and, if needed, a Planning Commission interpretation (§ 84-2.002(d)).
The zoning system applies to all public and private uses on land in unincorporated areas (§ 82-2.004), and the County can enforce compliance (§ 82-28.606).
Where a district boundary crosses a lot, the “least restricted” district’s rules carry over 30 feet past the line (§ 82-10.006).

For base-zone allowances and dimensional rules referenced by overlays, see the County’s Zoning, Land Use, and Development Standards pages.

Overlay/Combining Districts at a Glance

Overlay District	Core intent/effect	Where it applies	Does it override base zoning?	Code reference
Cannabis Exclusion (-CE) combining district	Establishes cannabis-related restrictions; all underlying uses remain allowed except as limited by the chapter	Acalanes Ridge, Alamo, Bethel Island, Blackhawk, Bollinger Canyon, Contra Costa Centre, Knightsen, Sandmound Slough, Saranap	Yes — overlay governs on conflict	§ 84-86.204, § 84-86.206, § 84-86.210, § 84-86.208
SD-1 Special District (combining)	A combining district that can be applied to certain residential/agricultural contexts; imposes additional development standards	May be combined with planned unit or agricultural districts in a general plan residential area, or with single- or two-family districts	Not stated; development standards apply once combined	§ 814-2.402, § 814-2.802, § 814-2.818

District-by-District Details

Cannabis Exclusion (-CE) Combining District

Purpose and effect:
- The chapter defines “commercial cannabis activities” and establishes a cannabis-focused combining district (§ 84-86.208). Where the overlay conflicts with underlying zoning, the overlay’s requirements prevail (§ 84-86.206).
Typical permitted uses:
- “All uses allowed in the underlying zoning district are permitted within the -CE district,” except as provided by § 84-86.212 (§ 84-86.210). Specific prohibited uses under § 84-86.212 are not included in the source materials. Not found in source materials.
Key dimensional standards:
- The overlay does not set standalone dimensional standards in the provided sections; underlying setbacks, height, parking, and other development standards continue to apply unless a conflict is shown. Not found in source materials.
Where it applies:
- Unincorporated communities/areas: Acalanes Ridge, Alamo, Bethel Island, Blackhawk, Bollinger Canyon, Contra Costa Centre, Knightsen, Sandmound Slough, and Saranap (§ 84-86.204).
Practical notes:
- Treat -CE as a use filter layered on your base zone. If your use involves “commercial cannabis activities” as defined in Chapter 84-86, expect additional limits; the overlay governs in the event of conflict (§ 84-86.206). For non-cannabis uses, follow the base zone and countywide rules such as Design Review, Signage, and Landscaping and Screening where applicable. Verify with the jurisdiction.

SD-1 Special District (Combining)

Application:
- The SD-1 district may be combined with any planned unit district or agricultural district in a general plan residential area, or with any single-family or two-family residential district (§ 814-2.402).
Purpose:
- Not provided in the source materials. Not found in source materials.
Typical permitted uses:
- SD-1 functions as a combining district, so underlying district uses remain the reference; SD-1 adds development standards contained in its chapter. Specific allowed or prohibited uses are not provided. Not found in source materials.
Key dimensional standards:
- The chapter states its development standards are the “minimum necessary” to accomplish its intent (§ 814-2.802), and allows “improvement exceptions” to other Titles (7 and 9) when needed to meet SD-1 standards and findings (§ 814-2.818). Numeric standards are not provided. Not found in source materials.
Where it applies:
- Parcel-specific where adopted; confirm via the County zoning map (§ 84-2.002). Verify with the jurisdiction.
Practical notes:
- If your parcel carries the SD-1 suffix, expect supplemental development standards beyond the base zone. Review the adopted ordinance mapping SD-1 to your site, and coordinate early on potential exceptions or variances through the County’s Variances and Exceptions process if conflicts arise. Verify with the jurisdiction.

Overlay boundary and mapping rules that matter

Topic	Practical rule	Why it matters	Code reference
Official zoning/overlay map	The zoning map (paper and digital) is the official record; staff records amendments and applies interpretation rules if boundaries are unclear	Establishes whether an overlay applies to your parcel	§ 84-2.002(a)–(d)
Split-lot rule	On lots divided by a district boundary, the least-restrictive district’s rules extend 30 feet into the other district	May expand or limit what fits near the line (e.g., structures, uses)	§ 82-10.006
Countywide applicability	Zoning rules apply to all public/private land uses in unincorporated areas	Confirms overlays bind both public and private projects	§ 82-2.004
Enforcement	Projects must comply with zoning and applicable regulations	Non-compliance can result in enforcement	§ 82-28.606

Interactions with other County frameworks

Base zoning and land-use allowances continue to govern unless an overlay states otherwise. Start with your base district’s Land Use table and Development Standards.
Overlays do not automatically change whether a use or structure is nonconforming; see Nonconforming Uses. Verify with the jurisdiction.
Some County policies apply countywide and are not overlays (for example, the 65/35 Land Preservation Plan in Division 82, Chapter 82-1). Its definitions section clarifies “land within the county” and “nonurban uses” (§ 82-1.032). Substantive siting or density rules are not provided in the source materials. Not found in source materials.
If a property is within an agricultural preserve or under a Williamson Act contract, separate Title 810 standards apply (§ 810-2.202, § 810-2.402, § 810-4.202, § 810-4.406). These are not overlays but can constrain use independently of zoning.

Checklist

Confirm your parcel is in the unincorporated area and identify base zoning on the County zoning map (§ 84-2.002; § 82-2.004).
Check for a combining suffix on your map label (e.g., “-CE” or “SD-1”) and read the applicable chapter (§ 84-2.002; § 84-86.204; § 814-2.402).
If a boundary splits your lot, apply the 30-foot split-lot rule before laying out improvements (§ 82-10.006).
For -CE sites, confirm whether your proposal involves “commercial cannabis activities” as defined (§ 84-86.208) and whether § 84-86.212 limits them. Not found in source materials.
For SD-1 sites, obtain the SD-1 development standards applicable to your parcel (§ 814-2.802; § 814-2.818). Not found in source materials.
Cross-check applicable Design Review, Parking, Signage, and Landscaping and Screening requirements; overlays do not generally waive countywide standards unless stated. Verify with the jurisdiction.
If constraints create hardship, discuss options under Variances and Exceptions.

Risks & Ambiguities

Issue	Why it matters	What to verify
Missing text for -CE prohibited uses (§ 84-86.212)	You can’t confirm exactly which cannabis-related activities are barred without it	Obtain § 84-86.212 from the County; confirm whether any limited cannabis activities are allowed
SD-1 purpose and numeric standards not provided	Without standards, design and entitlement strategies are guesswork	Request the full SD-1 chapter and any parcel-specific adopting ordinances; confirm findings and exception pathways (§ 814-2.802, § 814-2.818)
Split-lot application to overlays	The 30-foot carryover can change allowable siting near overlay edges	Have staff map the boundary precisely and apply § 82-10.006 to your site plan
Paper vs. digital map discrepancies	The ordinance recognizes possible minor discrepancies (§ 84-2.002(d))	Ask the Community Development Director to confirm the controlling boundary for your parcel
Interaction with Williamson Act contracts	Contracts can independently limit uses	If your parcel is under contract, reconcile Title 810 restrictions with zoning/overlays (§ 810-4.406)
Countywide policy vs. overlay	The 65/35 Plan influences growth but is not an overlay	Confirm whether any plan policies add constraints beyond the overlay on your parcel (§ 82-1.032)

Plain-English Summary

In unincorporated Contra Costa County, overlays are map-based layers that add or modify rules on top of your base zoning. Two combining districts are confirmed: the -CE Cannabis Exclusion overlay (applies in nine unincorporated communities and prevails over conflicts) and SD-1 (a combining district for certain residential/agricultural settings with its own development standards). Always verify the overlay on the County zoning map and apply the 30-foot split-lot rule if a boundary crosses your property.

Information Gaps

Specific prohibited uses and any exceptions in the -CE district (§ 84-86.212). Not found in source materials.
The stated purpose, dimensional standards, and any procedural requirements of SD-1 beyond the general clauses (§ 814-2.802, § 814-2.818). Not found in source materials.
Whether overlays trigger any special Design Review thresholds unique to the combining district. Not found in source materials.

Source References

Contra Costa County Zoning Code: § 84-2.002 (Zoning map adopted) — library.municode.com
Contra Costa County Zoning Code: § 84-2.004 (Districts established)
Contra Costa County Zoning Code: § 82-2.004 (Application to unincorporated territory)
Contra Costa County Zoning Code: § 82-28.606 (Compliance)
Contra Costa County Zoning Code: § 82-10.006 (Land on district boundaries; 30-foot rule)
Contra Costa County Zoning Code: § 84-86.204, § 84-86.206, § 84-86.208, § 84-86.210 (Cannabis Exclusion (-CE) combining district)
Contra Costa County Zoning Code: § 814-2.402, § 814-2.802, § 814-2.818 (SD-1 combining district)
Contra Costa County Zoning Code: § 82-1.032 (65/35 Plan definitions)
Contra Costa County Zoning Code: § 82-2.018 (Zoning districts for open space)
Contra Costa County Zoning Code: § 810-2.202, § 810-2.402, § 810-4.202, § 810-4.406 (Agricultural preserves/Williamson Act context)

Sources

Source passages

Contra Costa County Zoning Code (§ 82-2.018) Medium relevance
Contra Costa County Zoning Code (§ 84-2.004) Medium relevance
Contra Costa County Zoning Code (§ 814-2.802) Medium relevance
Contra Costa County Zoning Code (§ 814-2.818) Medium relevance
Contra Costa County Zoning Code (§ 82-10.006) Medium relevance
Contra Costa County Zoning Code (§ 814-2.402) Medium relevance
Contra Costa County Zoning Code (§ 810-2.202) Medium relevance
Contra Costa County Zoning Code (§ 84-2.002) Medium relevance
Contra Costa County Zoning Code (§ 82-1.032) Medium relevance
Contra Costa County Zoning Code (§ 82-28.606) Medium relevance
Contra Costa County Zoning Code (§ 84-86.204) Medium relevance
Contra Costa County Zoning Code (§ 810-4.202) Medium relevance
Contra Costa County Zoning Code (§ 810-2.402) Medium relevance
Contra Costa County Zoning Code (§ 82-2.004) Medium relevance
Contra Costa County Zoning Code (§ 810-4.406) Medium relevance

Cited sections

Official Contra Costa County code library

Frequently asked questions

Where does the Cannabis Exclusion (-CE) overlay apply in unincorporated Contra Costa County?

It applies in Acalanes Ridge, Alamo, Bethel Island, Blackhawk, Bollinger Canyon, Contra Costa Centre, Knightsen, Sandmound Slough, and Saranap (§ 84-86.204). If a conflict arises between -CE and the base zone, the -CE rules govern (§ 84-86.206).

Does the -CE overlay ban all commercial cannabis activity on my property?

The chapter defines “commercial cannabis activities” and sets overlay rules, but the specific list of prohibited or limited activities is in § 84-86.212, which is not in the source materials (§ 84-86.208, § 84-86.210). Verify with the jurisdiction.

If an overlay boundary crosses my lot, which rules apply near the line?

The least-restrictive district’s rules extend 30 feet into the other side of the boundary on split lots (§ 82-10.006). This can expand or limit siting options close to an overlay edge—confirm the exact mapped line before designing.

Does an overlay change my setbacks, height, or parking?

Only if the overlay chapter says so. For -CE, the provided sections do not change dimensional or parking standards; base-zone development standards still apply (§ 84-86.210). Not found in source materials for any -CE dimensional changes.

What is the SD-1 combining district and where can it be used?

SD-1 may be combined with planned unit or agricultural districts in a general plan residential area, or with single- or two-family residential districts (§ 814-2.402). Its detailed standards and purpose are not included in the source materials; obtain the full SD-1 chapter (§ 814-2.802, § 814-2.818). Verify with the jurisdiction.

Do overlay districts override the base zoning in unincorporated areas?

When the overlay chapter says so, yes. The -CE overlay expressly governs if there is any conflict with the underlying district (§ 84-86.206). Otherwise, use the base zone plus any applicable overlay conditions.

How do I confirm whether my parcel has an overlay?

Check the official County zoning map—paper and digital versions are available, and staff records amendments (§ 84-2.002(a)–(c)). If a boundary is unclear, the code provides interpretation rules and a Planning Commission determination as a backstop (§ 84-2.002(d)).

Are overlays enforced the same as other zoning rules?

Yes. No structure or land may be developed or used contrary to zoning and applicable regulations; violations are enforceable (§ 82-28.606). Overlays are part of the zoning framework in unincorporated areas (§ 82-2.004).

General information, not legal advice.

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