Yolo County — Overlay Districts

Last reviewed: July 6, 2026

Overview

In unincorporated Yolo County, overlay districts are mapped zoning layers that sit “on top of” a base zone and add extra rules tied to location, resources, or safety. If an overlay conflicts with the underlying zoning, the overlay rules control per § 8-2.901 and § 8-2.903 . Overlays are shown by appending the overlay to the base zone (e.g., A-N/A-O), except Planned Development zones, which use PD-# labels (§ 8-2.903) . The County’s Specific Plan (S-P) is a base zone, not an overlay (§ 8-2.902) .

Bottom line: In the unincorporated areas, the overlay governs wherever it conflicts with the base zone (§ 8-2.901) .

Overlay districts Yolo County applies include the NH-O, AD-O (Clarksburg Agricultural District), DP-O, SG-O/SGR-O, TT-O, A-O, PD, and Special Building “B” overlays (§ 8-2.903; § 8-2.906) . Overlay zones generally rely on the same “Use Types” framework that applies to base zones (§ 8-2.904) .

How Yolo County Names and Applies Overlays

• Shown as “Base/Overlay” (example: A-N/A-O), except PD overlays, which are mapped as PD-## (§ 8-2.903) .
• Overlay area totals are summarized in Table 8-2.903-1 (e.g., AD-O covers 35,171 acres; DP-O covers 73,053 acres) (§ 8-2.903) .
• Allowed uses in overlay zones are typically those consistent with the base zone and the overlay’s stated plan or program (§ 8-2.903(a)–(g); § 8-2.904) .

Overlay District-by-District

Natural Heritage Overlay (NH-O)

• Purpose and area: Applies to conservation areas identified in the Yolo Natural Heritage Program/HCP-NCCP (§ 8-2.903(a)) .
• Typical permitted uses: Uses limited to those consistent with the adopted Natural Heritage Program/HCP-NCCP (§ 8-2.903(a)) .
• Key dimensional standards: Not found in retrieved materials. Verify with the jurisdiction.
• Special notes: Interim agricultural uses may be allowed prior to plan adoption with a Minor Use Permit if findings are made (§ 8-2.906(c)(2)) .

Agricultural District Overlay (AD-O) — Clarksburg Agricultural District

• Purpose and area: Applies to designated agricultural districts; currently implemented only in the Clarksburg area (§ 8-2.903(b); § 8-2.401) .
• Typical permitted uses: Enhanced agri-tourism and agricultural commercial uses beyond the base zones. Examples in Clarksburg: small visitor kiosks (allowed), picnic areas (allowed), permanent public bathrooms (Site Plan Review), feed stores up to 2,000 sf (Site Plan Review) and over 2,000 sf (Minor Use Permit), and tiered thresholds for bed-and-breakfasts and special event facilities (§ 8-2.401(b)–(c)) .
• Key dimensional standards: Overlay-specific operational standards include permeable permanent parking surfaces and paved ADA spaces (§ 8-2.401(c)(1)(i))—coordinate with County parking .
• Where it applies: Parcels in the Clarksburg Area Plan designated Agriculture (§ 8-2.401(a)) .

Delta Protection Overlay (DP-O)

• Purpose and area: Covers the State-designated Primary Zone of the Sacramento–San Joaquin Delta to align local entitlements with the Delta Protection Commission’s Land Use and Resource Management Plan (§ 8-2.903(c)) .
• Typical permitted uses: Those consistent with the base zone and the Commission’s LRMP; County notes reiterate this consistency requirement (§ 8-2.903(c); table note referencing § 8-2.906(f)) .
• Key dimensional standards: Not found in retrieved materials. Verify with the jurisdiction.

Sand and Gravel Overlay (SG-O) and Sand and Gravel Reserve Overlay (SGR-O)

• Purpose and area: Apply to MRZ-2 mineral resource areas and existing mining operations (§ 8-2.903(d)) .
• Typical permitted uses: Mining and related uses consistent with the Cache Creek Area Plan/Specific Plan and Title 10 (note cites § 8-2.906(g), § 8-2.906(f), Title 10) .
• Key dimensional standards: Not found in retrieved materials. Verify with the jurisdiction.

Tribal Trust Overlay (TT-O)

• Purpose and area: Identifies tribal trust lands held in federal trust for recognized tribal governments (§ 8-2.903(e)) .
• Typical permitted uses: Not specified in the zoning text beyond recognition of trust status; project-specific coordination is typical. Not found in retrieved materials.
• Key dimensional standards: Not found in retrieved materials. Verify with the jurisdiction.

Airport Overlay (A-O)

• Purpose and area: Applied within a 10,000-foot radius around the Yolo County Airport and within mapped “safety zones” to regulate uses and heights per the Airport CLUP (§ 8-2.903(f)) .
• Typical permitted uses: Uses compatible with airport safety; restrictions on vegetation and structural height per CLUP and California PUC § 21659 (County note) .
• Key dimensional standards: Height and use restrictions tied to CLUP safety zones; exact numeric height planes are set by the CLUP/PUC framework. Not found in retrieved materials.

Planned Development Overlay (PD-##)

• Purpose and area: Enables flexible, master-planned development with superior design; mapped as PD-## over a compatible base zone (e.g., R-L/PD-45). Not intended for agricultural zones or uses (§ 8-2.903(g)) .
• Typical permitted uses: Any use mix consistent with the General Plan and associated base district where the approved PD ordinance sets the standards (§ 8-2.906(a)(2), (4)) .
• Key dimensional standards: Can deviate from base standards if the total development is improved; otherwise base standards apply. Minimum PD size is 2 acres (§ 8-2.906(a)(1)–(3)) .
• Where it applies: Retained PDs include, for example, PD-45 (Wild Wings, R-L), PD-56 (Dunnigan Truck & Travel Center, C-H), and others listed in Table 8-2.903-2 (§ 8-2.903(g); Table 8-2.903-2) .

Special Building Overlay (“B”)

• Purpose and area: Applied to development-zoned areas lacking public water and wastewater; enforces larger minimum parcel sizes to ensure on-site well/septic feasibility (§ 8-2.906(b)) .
• Typical permitted uses: Same as the base zone, but creation of new lots and the issuance of home building permits must meet the overlay minimum parcel size. Existing legal lots are not downzoned for buildability (§ 8-2.906(b)) .
• Key dimensional standards: Minimum parcel size for new lots is 2 acres (mapped as “B87,” i.e., ~87,000 sf). Used in areas such as Capay Valley, The Hardwoods (Dunnigan), and Patwin Road (Davis) (§ 8-2.906(b)) .

Quick Reference — What the Overlays Do

How Overlays Interact with Other County Rules

• Overlays add to base district development standards and can change what’s allowed or how it’s designed (§ 8-2.901; § 8-2.903) .
• Overlay rules are applied using the County’s Use Types system (§ 8-2.904) and processed via zoning clearance, Site Plan Review, or Use Permit as specified (§ 8-2.904; overlay tables) .
• Some PD overlays govern signage or design standards for a project area (note in signage tables) .
• If an overlay renders a legacy use or structure out of step, see Nonconforming Uses. Relief from overlay standards, if any, runs through Variances and Exceptions.
• Landscaping and screening commitments may be built into PDs or special overlay approvals—coordinate with Landscaping and Screening.

Checklist

• Confirm your parcel’s base district and any overlays on the County zoning map; overlays appear after the slash (e.g., A-N/A-O) (§ 8-2.903) .
• Identify the controlling overlay section(s) and whether overlay rules override base zoning (§ 8-2.901) .
• For AD-O (Clarksburg), check the permitted use table and any site standards (e.g., parking surfaces) (§ 8-2.401(b)-(c)) .
• For A-O, verify CLUP safety zone, allowed uses, and height envelopes (PUC § 21659 reference) (§ 8-2.903(f); note) .
• For SG-O/SGR-O, confirm alignment with the Cache Creek plan and Title 10 (note citing § 8-2.906(g)) .
• For PD-##, obtain the PD ordinance and precise plan; note any deviations from base setbacks/heights and required design review (§ 8-2.906(a)) .
• For “B” overlay, confirm the 2-acre minimum applies to new lots, not existing legal parcels (§ 8-2.906(b)) .
• Confirm whether Site Plan Review or a Use Permit is required; some overlays use special tables for permit type (§ 8-2.904; § 8-2.401) .

Risks & Ambiguities

Plain-English Summary

If your unincorporated Yolo County property has an overlay, that layer adds special rules on top of your base zoning. The overlay always wins if there’s a conflict. Some overlays are location-based (Airport, Delta, Natural Heritage), some are resource-based (Sand and Gravel), and others are project-specific (Planned Development) or infrastructure-based (“B” overlay for well/septic). Start by identifying overlays on your parcel, then check the right section of the code and, when relevant, any outside plan the overlay references.

Source References

• § 8-2.901 Purpose; overlay prevails over base
• § 8-2.902 Specific Plan (S-P) zone (not an overlay)
• § 8-2.903 Overlay Zones; naming convention; zone list; A-O, PD summaries; Table 8-2.903-1; Table 8-2.903-2 (PDs)
• § 8-2.904 Use Types framework (applies to overlays)
• § 8-2.401 Clarksburg Agricultural District Overlay (AD-O implementation) — uses/standards table and parking surface requirement
• § 8-2.906 Overlay-specific standards: PD procedures and minimum area; “B” overlay 2-acre standard and B87; NH-O interim uses; cross-references to DP-O, SG/SGR
• Signage note acknowledging PDs can govern signage for some zones (context)

Retrieved passages

• Yolo County Zoning Code High relevance show source text
• Yolo County Zoning Code High relevance show source text
• Yolo County Zoning Code High relevance show source text
• Yolo County Zoning Code (§ 3) High relevance show source text
• Yolo County Zoning Code (Article 9) High relevance show source text
• Yolo County Zoning Code (Section 8-) High relevance show source text
• Yolo County Zoning Code (Section 8-2.401) High relevance show source text
• Yolo County Zoning Code (§ 4) Medium relevance show source text

Cited sections

• § 8-2.901 Purpose; overlay prevails over base (§ 8-2.901)
• § 8-2.902 Specific Plan (S-P) zone (not an overlay) (§ 8-2.902)
• § 8-2.903 Overlay Zones; naming convention; zone list; A-O, PD summaries; Table 8-2.903-1; Table 8-2.903-2 (PDs) (§ 8-2.903)
• § 8-2.904 Use Types framework (applies to overlays) (§ 8-2.904)
• § 8-2.401 Clarksburg Agricultural District Overlay (AD-O implementation) — uses/standards table and parking surface requirement (§ 8-2.401)
• § 8-2.906 Overlay-specific standards: PD procedures and minimum area; “B” overlay 2-acre standard and B87; NH-O interim uses; cross-references to DP-O, SG/SGR (§ 8-2.906)
• Signage note acknowledging PDs can govern signage for some zones (context)
• YoloCounty_ZoningCode.md

• Official Yolo County code library