Local zoning · San Luis Obispo County

San Luis Obispo County — Overlay Districts

Overlay Districts under the San Luis Obispo County local zoning and planning code, with the controlling citations.

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Last reviewed: July 6, 2026

Overview

In unincorporated areas of San Luis Obispo County, “overlay” districts are called Combining Designations and appear on the official Land Use Element maps alongside the base land use category. They flag hazards, sensitive resources, or special policy areas and layer extra standards on top of base zoning. Title 22 of the County Code establishes which overlays exist, where they apply, and how they modify uses, permits, and development standards (§ 22.01.030; Table 2‑1; § 22.14.020 ).

Plain-English rule: If an overlay’s standards conflict with other Title 22 rules, the overlay controls; if an overlay conflicts with an adopted planning area standard, the planning area standard controls (§ 22.14.020 ).

Related topics you’ll likely touch as you apply overlays include the County’s zoning, land use, development standards, parking, design review, historic preservation, and signage pages.

What overlays exist in Title 22?

Title 22 recognizes these Combining Designations: AR, EX, FH, GSA, H, LCP, MRA, RE, SRA, TDCR, and TDCS (Table 2‑1; § 22.01.030 ).

District-by-District Standards and Guidance

Airport Review Area (AR)

  • Purpose and where it applies. Protect navigable airspace; applies beneath FAA Part 77 “imaginary surfaces” and within areas adopted by the Airport Land Use Commission (§ 22.14.030.A ). Area-specific AR maps and rules are also embedded in planning area standards for Paso Robles (North County), San Luis Obispo, and Oceano (§ 22.94.020.A; § 22.96.020.A; § 22.98.020.A ).
  • Typical permitted/limited uses. Uses are limited to those the applicable Airport Land Use Plan (ALUP) tags as “compatible” or “conditionally approvable” (§ 22.14.030.B; § 22.94.020.A.2; § 22.96.020.A.2; § 22.98.020.A.2 ).
  • Key dimensional/development standards. Height can’t penetrate Part 77 surfaces unless the Airport Manager allows parity with nearby terrain; avigation easements may be required (§ 22.14.030.D–F ).
  • Notes. Appeals/variances route first to the Airport Land Use Commission (§ 22.14.030.G ).

Energy and Extractive Resource Area (EX)

  • Purpose and where it applies. Protects areas of mineral/petroleum extraction and major electric generation, and state-designated significant mineral areas (§ 22.14.040.A ).
  • Typical permitted/limited uses. Resource extraction and energy production are focal uses. Numerous non-resource uses are prohibited (e.g., schools, libraries, lodging beyond small B&Bs) (§ 22.14.040.B ).
  • Key standards and permits.
    • Minimum parcel size for new parcels: 10 acres unless a larger size is triggered elsewhere (§ 22.14.040.C ).
    • Non-extraction/non-generation uses generally need at least a Minor Use Permit and a mineral resource report; approval requires a finding they won’t hinder ongoing or future extraction/energy operations (§ 22.14.040.D–E ).
    • Extraction and generation projects must also meet Chapters 22.34 (petroleum) and 22.32 (energy-generating facilities) and mining in 22.36 (§ 22.14.040.D–E; see also § 22.34.050 example for petroleum facilities ).

Mineral Resource Area (MRA)

  • Purpose and where it applies. Identifies areas classified by the California Geological Survey as containing or likely to contain regionally significant mineral deposits (§ 22.14.050.A ).
  • Typical permitted/limited uses. Similar to EX, the MRA prohibits a range of urban/community uses (e.g., scrap/dismantling yards, small-scale manufacturing, clubs/lodges, libraries, religious facilities, camping, schools, restaurants, lodging beyond small B&Bs, waste sites, airfields/heliports) (§ 22.14.050.B; additional prohibited uses listed in MRA excerpt ).
  • Key standards and permits.
    • New parcels: minimum 10 acres unless a larger minimum applies (§ 22.14.050; “new subdivisions—minimum parcel size” in MRA excerpt ).
    • Discretionary approvals for non-extraction uses must not impair current/expanded extraction (§ 22.14.050; MRA processing excerpt ).

Flood Hazard Area (FH)

  • Purpose and where it applies. Applies to FEMA-identified special flood hazard areas; County adopts the Flood Insurance Study dated June 6, 2024, and FIRM maps by reference (§ 22.14.060.A ).
  • Typical permitted/limited uses. Temporary and emergency work can be authorized under strict conditions; existing lawful uses can continue (§ 22.14.060.B ).
  • Key standards.
    • Variances only upon specific hardship findings; “disclaimer of liability” applies (§ 22.14.060.F–G ).
    • Land divisions/lot line adjustments are prohibited if they create new building areas in the 100‑year flood zone unless a Flood Hazard Plan is approved (§ 22.14.060.H ).

Geologic Study Area (GSA)

  • Purpose and where it applies. Flags areas with seismic hazards (fault zones), high landslide risk, or liquefaction potential (§ 22.14.070.A ).
  • Typical permitted/limited uses. Uses allowed by base zoning but subject to GSA constraints; some projects require geologic reports (e.g., hillside development near Morro Bay per planning area standards) (§ 22.94.020.C ).
  • Key standards.
    • Parcel size tests in some residential categories are stricter “inside GSA” (e.g., Residential Suburban and Rural categories show larger minimums in slope tests) (§ 22.22.070; tables noting “Inside GSA” ).

Historic Site (H)

  • Purpose and where it applies. Protects archaeological and historic sites/structures; used where resources are of local, state, or national significance (§ 22.14.080.A ).
  • Typical permitted/limited uses. New structures and most modifications to historic resources require at least a Minor Use Permit, with application content and findings focused on resource protection (§ 22.14.080.C; approval findings and content ).
  • Key standards.
    • Parceling a historic structure onto a substandard lot is only by Conditional Use Permit with strict findings and a recorded restriction; transfer limited to a qualifying nonprofit or public agency; residential use may be prohibited on the small “historic parcel” (§ 22.14.080.B ).
    • Area-specific tweaks exist (e.g., San Luis Obispo sub-area narrows which sites trigger the § 22.14.080 MUP; Pozo Saloon requires CUP) (§ 22.96.020.B; § 22.104.050.A ).

Sensitive Resource Area (SRA)

  • Purpose and where it applies. Protects significant scenic, biological, watershed, and other resources; applies in mapped SRA areas and is part of the County’s Open Space program (§ 22.01.040.A.1; § 22.14.110, as renumbered ).
  • Typical permitted/limited uses.
    • SRA modifies permit processing: CEQA determination can elevate projects to a Conditional Use Permit; specific approval findings are required (§ 22.14.110.B–C.4–C.5 ).
    • Surface mining is prohibited in SRA unless the site is also in EX and obtains mining approvals (§ 22.14.110.D.1 ).
  • Key standards.
    • Minimum resource setbacks: 100 ft from mean high tide, 75 ft from any lakeshore, 50 ft from any stream bank (unless a CUP authorizes otherwise) (§ 22.14.110.D.2 ).
    • Project design must avoid degrading wetlands/riparian features; protect prominent geo-features and sensitive species (§ 22.14.110.D.3–D.5 ).
    • Planning area overlays add site-specific SRA rules (e.g., Soda Lake SRA prohibits new construction/extraction; highway corridor design criteria in SLO/South County enable ministerial approvals when strict visibility/siting standards are met) (§ 22.92.020.A; § 22.96.020.C and corridor standards excerpts ).

Renewable Energy Area (RE)

  • Purpose and where it applies. Prioritizes and streamlines appropriate renewable energy development (primarily solar) in mapped areas (§ 22.14.100.A ).
  • Typical permitted/limited uses and thresholds.
    • Tier 2 Solar Electric Facilities (SEFs) up to 40 acres within RE may be eligible for Site Plan Review if they meet location/criteria and specified development standards; larger or more complex projects default to the standard energy-facility rules in § 22.32 (§ 22.14.100.E–F; Tier thresholds ).
    • If biological reports show listed species or critical habitat, RE streamlining does not apply and Chapter 22.32 controls (§ 22.14.100.F.2 ).

Transfer of Development Credit Sending Site (TDCS)

  • Purpose. Identifies parcels with conservation easements or that participate in community-based TDC programs for permanently retiring development potential (§ 22.14.120 ).
  • Interplay with the TDC program. Detailed program mechanics (eligibility, application, credit geography) are in Chapter 22.24 (§ 22.24.060–.100; § 22.24.080 regional credit rules ).

Transfer of Development Credit Receiving Site (TDCR)

  • Purpose. Flags sites that used TDCs to achieve densities beyond base standards or that are in community-based TDC program areas (§ 22.14.130 ).
  • Mechanics. After credits are used, the site is placed in TDCR by a County-initiated General Plan amendment; eligibility criteria include being outside SRA/FH/GSA and other constraints (§ 22.24.090.C; § 22.24.070.A.5 ).

Local Coastal Plan Area (LCP)

  • What it means. Marks the Coastal Zone; Title 22 does not apply there—projects are regulated by Title 23 (Coastal Zone Land Use Ordinance) (§ 22.14.090; § 22.01.050 ).

Quick-Glance Standards Table

Overlay What it does Key thresholds/standards Typical permit path Code Reference
AR Keeps uses/structures compatible with airport safety Height below FAA Part 77 surfaces; avigation easements as required; must meet ALUP “compatible/conditional” use lists Often Zoning Clearance to MUP/CUP depending on base use; ALUC consistency review § 22.14.030; § 22.94.020.A; § 22.96.020.A; § 22.98.020.A
EX Protects energy/extraction areas Many community/assembly uses prohibited; min 10-acre parcels; mineral report for non-extraction uses MUP/CUP depending on use; specialized standards in §§ 22.32, 22.34, 22.36 § 22.14.040; § 22.34.050 (example)
MRA Highlights MRZ-significant mineral deposits Prohibits urban/assembly uses; 10-acre minimum parcels; protect extraction feasibility Discretionary permits must not impair extraction § 22.14.050
FH Manages 100‑year flood hazards FEMA FIS (June 6, 2024) adopted; land divisions creating new building areas in FH prohibited unless approved plan Varies; variances require strict findings § 22.14.060
GSA Flags seismic/landslide/liquefaction areas Geologic reports as required; larger “inside GSA” parcel minimums in some categories Varies by project; subdivision tests adjust inside GSA § 22.14.070; § 22.22.070; area-specific: § 22.94.020.C
H Protects historic/archaeological resources MUP for new/modified structures; strict subdivision/ownership conditions; tailored area rules MUP/CUP with findings to protect significance § 22.14.080; § 22.96.020.B; § 22.104.050.A
SRA Protects scenic/biologic/watershed resources Permit processing escalators; shoreline setbacks 100/75/50 ft; no mining unless also EX ZC/MUP/CUP with CEQA-based pathway, required findings § 22.14.110 (renumbered); § 22.92.020.A; corridor standards excerpts
RE Prioritizes siting of renewable energy Tier 2 SEFs ≤40 acres may be Site Plan Review if criteria met; otherwise § 22.32 applies Site Plan Review or MUP/CUP per size/criteria § 22.14.100
TDCS/TDCR Implements TDC conservation/receiving TDCS = conserved sending; TDCR = receiving map label after credits used Map changes via GPA; eligibility rules in Ch. 22.24 § 22.14.120–.130; § 22.24.070–.100

Note: In all overlays, base standards for setbacks, heights, parking, landscaping, and signs still apply unless an overlay or planning area standard is stricter; see Development Standards, Parking, Landscaping and Screening, and Signage.

Checklist

  • Confirm overlays on the parcel using the official Land Use Element maps and Table 2‑1 (§ 22.01.030; Table 2‑1 ).
  • If in AR, show ALUP consistency, height compliance with FAA Part 77, and provide any required avigation easement (§ 22.14.030.D–F; § 22.94.020.A–§ 22.98.020.A ).
  • If in FH, identify FIRM zone and demonstrate flood compliance; no land division creating new building areas without an approved Flood Hazard Plan (§ 22.14.060.A, H ).
  • If in GSA, scope geotechnical needs and apply any “inside GSA” parcel-size tests as applicable (§ 22.14.070; § 22.22.070 ).
  • If in H, prepare a MUP/CUP package with required findings and any subdivision/ownership instruments if creating a “historic parcel” (§ 22.14.080.B–C ).
  • If in SRA, include resource protection measures, address shoreline/watercourse setbacks, and expect CEQA-driven permit elevation (§ 22.14.110.C–D ).
  • If in EX or MRA, verify prohibited uses, parcel minimums, and resource-compatibility findings; include mineral resource report for non-extraction uses (§ 22.14.040–.050 ).
  • If in RE, size the facility against Tier 2/3 thresholds and confirm biological constraints (§ 22.14.100.E–F ).
  • If in TDCS/TDCR, coordinate with the County TDC Administrator on credits and mapping (§ 22.24.090–.100; § 22.14.120–.130 ).
  • If the site is in the Coastal Zone (LCP), switch to Title 23 (Coastal LUE); Title 22 does not apply (§ 22.14.090; § 22.01.050 ).

Risks & Ambiguities

Issue Why it matters What to verify
Overlay boundary precision Minor mapping differences can change permit type/setbacks Confirm the overlay polygon on the Official Land Use Maps and any area plan figures (§ 22.01.030; Article 9)
Dual overlays (e.g., SRA + EX) Overlays can conflict; stricter standard controls Apply § 22.14.020 priority rule; check area plan standards that may further limit uses (§ 22.14.020; § 22.90.020)
ALUP “compatibility” interpretations Determines whether a use is allowed in AR Use the correct Airport Land Use Plan and seek ALUC consistency (§ 22.94.020.A; § 22.98.020.A; § 22.14.030.B)
FEMA map updates in FH New FIRM revisions alter constraints Reference the latest FIS/FIRM adopted by § 22.14.060 and confirm with County Public Works (§ 22.14.060.A)
“Inside GSA” subdivision tests Affects minimum parcel sizes and feasibility Apply the correct category-specific tables (e.g., § 22.22.070) and any local geologic-report triggers (§ 22.94.020.C)
Historic resource scope in H Determines when MUP/CUP applies Check area plan lists (e.g., SLO sub-area limits § 22.14.080 application) and site’s listing status (§ 22.96.020.B)

Plain-English Summary

Overlays in unincorporated San Luis Obispo County don’t replace your base zoning—they add extra rules where there are airports, flood zones, geologic hazards, sensitive habitats/views, mineral/energy areas, historic sites, or TDC program sites. Start by confirming all overlays on your parcel; then follow the specific overlay’s permit path and standards (for example, airport height limits in AR, stream setbacks in SRA, or FEMA rules in FH), along with any area plan add‑ons. If your property lies in the Coastal Zone (LCP), you’ll use the Coastal ordinance instead.

Source References

  • Title 22—general adoption, maps, overlays list: § 22.01.030; Table 2‑1
  • Overlay precedence and applicability: § 22.14.020; Article 9 applicability § 22.90.020
  • AR overlay standards: § 22.14.030; North County § 22.94.020.A; SLO § 22.96.020.A; South County § 22.98.020.A
  • EX overlay standards: § 22.14.040; petroleum example § 22.34.050
  • MRA overlay standards: § 22.14.050 (and MRA prohibited uses/minimum parcel size excerpts)
  • FH overlay standards: § 22.14.060 (FIS/FIRM adoption; land division limits; variance findings)
  • GSA overlay standards: § 22.14.070; subdivision tests referencing “Inside GSA” e.g., § 22.22.070; area-specific report trigger § 22.94.020.C
  • H overlay standards (permits, findings, subdivision/ownership restrictions): § 22.14.080; SLO sub-area adjustment § 22.96.020.B; Pozo Saloon § 22.104.050.A
  • SRA overlay standards (permits, findings, setbacks) and planning-area specifics: § 22.14.110 (renumbered); § 22.92.020.A; corridor standards excerpts
  • RE overlay standards: § 22.14.100 (tiers/criteria; biological exceptions)
  • TDC overlays and program: § 22.14.120–.130; § 22.24.060–.100; § 22.24.080; § 22.24.090.C
  • Coastal Zone note: § 22.14.090; Title 22 applicability limits § 22.01.050

Sources

Retrieved passages

  • San Luis Obispo County Zoning Code (ARTICLE 11) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.14) Medium relevance
  • San Luis Obispo County Zoning Code (Section 22.06.060c) Medium relevance
  • San Luis Obispo County Zoning Code (section that) Medium relevance
  • San Luis Obispo County Zoning Code (Title by) Medium relevance
  • San Luis Obispo County Zoning Code (Title apply) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.22.) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.52) Medium relevance
  • San Luis Obispo County Zoning Code (Title do) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter apply) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.22.) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.22) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.98) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.92) Medium relevance
  • San Luis Obispo County Zoning Code (§ I) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.96) Medium relevance
  • San Luis Obispo County Zoning Code (Article 3.) Medium relevance
  • San Luis Obispo County Zoning Code (Article 8) Medium relevance
  • San Luis Obispo County Zoning Code (Section 22.24.070.B.) Medium relevance
  • San Luis Obispo County Zoning Code (§ 11) Medium relevance
  • San Luis Obispo County Zoning Code (Section 9.04.120) Medium relevance
  • San Luis Obispo County Zoning Code (Chapter 22.32.) Medium relevance
  • San Luis Obispo County Zoning Code (Section 22.62.060) Medium relevance
  • San Luis Obispo County Zoning Code (Section apply) Medium relevance
  • CBC § 22.10.090 (Section 22.10.090) Medium relevance
  • San Luis Obispo County Zoning Code (Section 22.06.060c) Medium relevance
  • San Luis Obispo County Zoning Code (Title shall) Medium relevance

Cited sections

Frequently asked questions

What are Combining Designations in unincorporated San Luis Obispo County?

They are overlay districts that add requirements on top of the base land use category to address hazards, resources, and special policy areas. They’re listed in Table 2‑1 and adopted via the Land Use Element maps (§ 22.01.030; Table 2‑1; § 22.14.020) .

How do Airport Review (AR) rules affect height and uses?

Projects must not penetrate FAA Part 77 surfaces; ALUP “compatible/conditional” use lists control; avigation easements may be required. Appeals/variances route first to the Airport Land Use Commission (§ 22.14.030.D–G; area plans incorporate ALUPs) .

Can I subdivide in the Flood Hazard (FH) overlay?

Land divisions and lot line adjustments are prohibited if they create new building areas in the 100‑year flood zone unless a Flood Hazard Plan is approved. The County has adopted the June 6, 2024 FEMA Flood Insurance Study and maps (§ 22.14.060.A, H) .

What does the Sensitive Resource Area (SRA) overlay require?

It can elevate permit type after CEQA review, requires findings to protect resources, and imposes setbacks from shorelines/watercourses (100/75/50 ft). Some area plans add stricter rules (e.g., Soda Lake SRA prohibits new construction/extraction) (§ 22.14.110.C–D; § 22.92.020.A) .

How do Geologic Study Area (GSA) overlays affect subdivisions?

Inside GSA, certain residential categories use larger minimum parcel sizes in slope tests; some hillside projects require geologic reports (e.g., near Morro Bay). Check § 22.22.070 and applicable area plan standards (§ 22.14.070; § 22.22.070; § 22.94.020.C) .

What’s different about EX vs. MRA overlays?

Both protect mineral/energy resources, but EX targets active/proposed extraction and energy generation; MRA marks state-classified significant mineral areas. Both restrict non-resource uses and require compatibility findings; EX links directly to §§ 22.32, 22.34, 22.36 for facility-specific standards (§ 22.14.040–.050) .

Do I always need a permit in the Historic (H) overlay?

Generally, new structures and most modifications need a Minor Use Permit with specific findings to protect the resource; special subdivision/ownership restrictions may apply if creating a “historic parcel.” Some area plans narrow which resources trigger these rules (§ 22.14.080; § 22.96.020.B) .

If my site is in the Coastal Zone (LCP overlay), does Title 22 apply?

No. The LCP overlay indicates the Coastal Zone, where Title 23 governs land use and development instead of Title 22 (§ 22.14.090; § 22.01.050) .

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