Local zoning · Arcata

Arcata — Overlay Districts

Q: What extra studies are triggered by the Natural Hazards overlay (:NH)?

Projects in :NH typically require geotechnical/geologic reports under the Geologic Hazard Review process (Chapter 9.62 ); the code explicitly requires compliance with § 9.62.020 when hazards are mapped § 9.28.050 file.

Overlay Districts under the Arcata local zoning and planning code, with the controlling citations.

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Last reviewed: July 3, 2026

Overview

Arcata uses a system of combining (overlay) zones—called “combining zones” in the Land Use Code—to layer site-specific restrictions or incentives on top of the city’s base zoning. Combining zones modify allowed uses, approvals, and project standards in limited geographic areas (for environmental protection, historic preservation, planned developments, cannabis, mobilehome parks, etc.). The combining-zone rules sit in the Arcata Land Use Code; applicability and mapping are controlled by the Zoning Map. See the Land Use Code for baseline mapping and district rules in § 9.12.020 and the combining-zone chapter § 9.28.010 – 9.28.020 .

Note: this page covers only what Arcata’s Land Use Code (the local zoning/land‑use ordinance) says about combining/overlay zones; it does not attempt to restate building code, state ADU law, or tenant law. For related items see parking, setbacks and site standards, and design review in Arcata’s menu (linked inline below).

Arcata Zoning (overlays and base districts): Arcata Zoning
Development standards & setbacks: Arcata Development Standards
Parking rules: Arcata Parking
Design review triggers: Arcata Design Review
ADU-specific local rules: Arcata ADUs
State building-code reference (Title 24): California Building Standards Code
Historic overlay procedures: Arcata Historic Preservation

How Arcata combines overlays with a base zone

The combining (overlay) zones are collected in Chapter 9.28 (Chapter title: “Combining Zones”). The chapter explains that any development in a combining zone must satisfy the overlay requirements in addition to the primary zoning district standards and other Land Use Code rules (§ 9.28.010 – 9.28.020) .
Mapping: combining zones are appended as suffixes to base-zone symbols on the City Zoning Map (for example RVL:NH). The Zoning Map and district list live under § 9.12.020 (Zoning Map and Zoning Districts) .
Where the combining zone sets different or additional requirements, those overlay rules control for projects in that overlay; where it is silent, the base zone and other chapters (site standards, parking, design review) apply—conflicts are resolved per the code’s rules of interpretation (§ 9.28.020 and § 9.10.050) .

District-by-district breakdown

Below are Arcata’s active combining/overlay zones in the Land Use Code with the code reference and the decision‑relevant points you must check. Each subsection references the controlling section(s) of the Land Use Code.

Historic Landmark combining zone — :HL

Purpose: protect significant historic structures and districts; preserve character and key features § 9.28.040 .
Typical permitted uses: the overlay does not create new commercial/residential uses beyond the base zone; it restricts alterations and adds procedural requirements (designation, referral to Historic Landmarks Committee, review). See Chapter 9.53 for preservation rules and incentive uses § 9.28.040 .
Key standards & approvals: designation and alteration are subject to notice, referral, and potential City Council action; design review/landmark protections apply (see Chapter 9.53) § 9.28.040 .
Where it applies: sites listed/rezoned by ordinance; removal requires a rezoning § 9.28.040 .

Natural Hazards combining zone — :NH

Purpose: identify highest-risk earthquake, landslide, liquefaction, and flood areas and add procedural and study requirements § 9.28.050 .
Typical permitted uses: uses allowed by the primary zone may be allowed, but certain critical facilities are restricted or prohibited; levees/dikes and similar flood-protection works may require permits § 9.28.050 .
Key standards & approvals: projects in an :NH require compliance with the Geologic Hazard Review process (Chapter 9.62) and, where applicable, flood‑hazard review in the Municipal Code; geotechnical/soils studies are often required § 9.28.050 and § 9.62.020 file.
Where it applies: mapped high-hazard areas per Seismic Safety Element and Zoning Map § 9.28.050 .

Neighborhood Conservation Area combining zone — :NCA

Purpose: preserve neighborhood character and protect historic resources; ensure compatibility of new construction § 9.28.060 .
Typical permitted uses: same as base zone, but many exterior changes and new constructions require Design Review § 9.28.060 .
Key standards & approvals: Design Review is required for new construction and alterations within an NCA; design must be compatible with existing character (findings required) § 9.28.060 and Design Review rules § 9.72.040 file.
Where it applies: mapped NCA areas on the Zoning Map § 9.28.060 .

Planned Development combining zone — :PD

Purpose: permit master-planned, coordinated projects with possible exceptions to base standards (setbacks, coverage, density, parking, height) § 9.28.070 .
Typical permitted uses: land uses follow the primary district, but PD process can authorize mixed types and site-specific modifications § 9.28.070 .
Key standards & approvals: Planned Development Permit per § 9.72.070; PD may authorize exceptions to setbacks, site coverage, parking (verify exact PD terms in the approved PD permit) § 9.28.070 .
Where it applies: sites rezoned to include :PD or where PD overlay appears on the Zoning Map § 9.28.070 .

Plaza Area and Special Considerations — :PA and :SC / SCC / SCI / SCP

Purpose: area-specific design directions and parcel-level requirements (listed under special considerations tables) § 9.28.080 – 9.28.090 and related tables in Article 2 and 9.26 (Special Considerations) file.
Typical permitted uses: base zone uses subject to special parcel-level conditions (e.g., reduced coverage, required buffers, master planning). See Table entries for site-specific requirements (SCC/SCR/SCI/SCP tables) § 9.26.070 and zoning tables § 9.28.080 – 9.28.090 .
Key standards & approvals: site plan/master plan requirements, possible buffering, parking and circulation conditions; consult the special table row for a given parcel § 9.26.070 .
Where it applies: listed parcels/areas in the General Plan/Zoning Map table entries § 9.26.070 .

Wetland Protection and Stream Protection combining zones — :WP and :SP

Purpose: protect ESHA, wetlands, streams and associated buffer areas; ensure developments do not impair habitat or watercourse function § 9.28.100; detailed rules in Chapter 9.59 (ESHA) § 9.59.010 – 9.59.050 file.
Typical permitted uses: only limited uses and activities compatible with protecting riparian/wetland function (agriculture compatible uses, restoration, limited access improvements) § 9.59.050 .
Key standards & approvals:
- Environmental Buffer Area (EBA) widths: baseline 100 ft in undeveloped reaches, 25 ft in existing developed reaches; up to 250 ft in areas of significant riparian vegetation; variances are possible only with strong findings § 9.59.050(A)(1–3) .
- Any discretionary approval affecting ESHA requires the findings in § 9.59.090 and, before permits take effect, a recorded Notice of Protection on the title § 9.59.090; § 9.59.100 .
Where it applies: mapped ESHA and Protected Watercourse Map; adjacent properties within 250 ft also subject to the Chapter § 9.59.020 .

Housing for Homeless combining zone — :HH

Purpose: identify sites where emergency shelters, transitional and supportive housing may be permitted as a permitted use subject to the standards in Section 9.42.200 § 9.28.110 .
Typical permitted uses: emergency shelter/transitional/supportive housing where the site is inside the combining zone and meets the specific criteria § 9.28.110 .
Key standards & approvals: must comply with Section 9.42.200 and base-zone site standards; if the facility is outside the combining area or fails to meet 9.42.200 criteria then the base-zone permits apply § 9.28.110 .
Where it applies: mapped :HH sites (Figures 2-23.1 and 2-23.2) § 9.28.110 .

Cannabis Innovation Zone combining zone — :CIZ

Purpose: create areas for commercial cannabis activities (cultivation, processing, warehousing, research, testing) with special limits and permit rules § 9.28.130 .
Typical permitted uses: cannabis cultivation and related commercial cannabis activities, subject to Arcata commercial cannabis activity permits and use-permit limits (Area 2 use permits limited to 30 active) § 9.28.130 .
Key standards & approvals:
- Cultivation area caps: generally limited to 25% of a parcel’s total building floor area and capped at 4,000 sf per lease/business unless a use permit increases those limits § 9.28.130(D)(1)(a–c) .
- Each parcel with cultivation must provide at least one independently accessible, occupancy-ready commercial/industrial space ≥600 sf that is not used for cultivation prior to issuing a CO for cultivation § 9.28.130(D)(1)(d) .
- Cannabis activity permits and other state/local licenses also required § 9.28.130(C) .
Where it applies: Areas 1 and 2 as shown in Figure 2-25 and the Zoning Map § 9.28.130 .

Mobilehome Park combining zone — :MP

Purpose: preserve mobilehome parks as permitted uses and restrict non‑park uses; require special process before a park can be redeveloped or rezoned § 9.28.140 .
Typical permitted uses: only Mobilehome Park and accessory uses allowed where :MP overlay applies; base‑zone uses (unless accessory to a mobilehome park) are excluded § 9.28.140(B–C) .
Key standards & approvals:
- Any change that ceases or converts an :MP requires a zone amendment and additional findings (including replacement housing or in‑lieu fee equal to 20% replacement) § 9.28.140(D) .
- Development within :MP must otherwise comply with primary‑zone standards and Section 9.42.120 (mobilehome park standards) § 9.28.140(C) .
Where it applies: specifically listed mobilehome parks (Town & Country, Lazy J, Valley West, Arcata Mobilehome Park, Sandpiper) § 9.28.140(B) .

Quick reference table — combining zones (decision‑relevant items)

Overlay (code)	Purpose / Typical effect	Decision‑relevant checklist items	Code reference
:HL	Protect historic resources; trigger historic review and possible limitations on alterations	Check landmark designation, HLC referral, Ch. 9.53 requirements, design review	§ 9.28.040
:NH	High seismic/landslide/flood hazard overlay; site-specific geologic requirements	Geologic Hazard Review, possible geotech reports, limits on critical facilities	§ 9.28.050; § 9.62.020 file
:NCA	Protect neighborhood character; design review required	Design Review approval and compatibility findings	§ 9.28.060; § 9.72.040 file
:PD	Planned master development; may modify setbacks/parking/density	Planned Development Permit (9.72.070); check PD permit conditions for exceptions	§ 9.28.070; § 9.72.070
:SP / :WP	Stream/wetland protection; EBAs and strict ESHA findings	Biological assessment, buffer widths, recorded Notice of Protection	§ 9.28.100; § 9.59.050; § 9.59.100 file
:HH	Sites where emergency/transitional housing is a permitted use	Confirm site is inside :HH and meets 9.42.200 criteria	§ 9.28.110; § 9.42.200
:CIZ	Cannabis industrial/commercial overlay with caps & permitting	Cannabis commercial activity permit; cultivation area limits; CO requirements	§ 9.28.130
:MP	Mobilehome park preservation overlay; restricts non‑park redevelopment	Rezoning for closure requires replacement housing findings / in‑lieu fee	§ 9.28.140

Checklist

If your parcel falls inside any combining zone, at minimum:

Confirm the combining zone suffix on your parcel using the City’s Zoning Map per § 9.12.020 .
Read the overlay’s specific chapter in Chapter 9.28 (and any supplemental chapters—e.g., 9.59 for :SP/:WP, 9.53 for :HL) and note mandatory findings § 9.28.010–020; § 9.59.010–100; § 9.28.040 filefile.
Confirm required technical studies (biological assessment for ESHA § 9.59.040; geotechnical report for :NH per § 9.62.020) file.
Determine permit path: administrative clearance, Use Permit, Planned Development Permit (§ 9.72 references) or Design Review (§ 9.72.040) as required by the overlay § 9.28.xx file.
Check compatibility with local site rules: setbacks, lot coverage, height, parking requirements and landscaping in the base zone and Article 3 (site standards) § 9.30.020 and related tables; review Arcata Development Standards and Arcata Parking for local operational details § 9.30.020 .
Where applicable record required notices prior to issuance (ESHA Notice of Protection § 9.59.100) .
Verify whether the overlay imposes extra public‑notice or referral steps (Historic Landmarks Committee, HLC referral for :HL) § 9.28.040 .

Risks & Ambiguities

Issue	Why it matters	What to verify
Overlay vs. base‑zone conflicts	Combining zones add requirements; failure to follow overlay text can stop permits	Confirm which provision applies; resolving conflicts follows code rules—see § 9.28.020 and § 9.10.050 file
Buffer widths for streams/wetlands	EBAs are large (25–100–250 ft) and can eliminate developable area	Obtain a Biological Assessment early; check § 9.59.050(A) and potential variance rules § 9.59.050
Geologic study triggers	:NH may require detailed geotechnical work and can limit critical facilities	Confirm hazard mapping and whether Chapter 9.62 report is required § 9.28.050; § 9.62.020 file
Parcel‑specific special considerations	SCC/SCI/SCP rows include parcel‑level mandatory conditions (e.g., site master plans, coverage limits)	Review the relevant table row in Chapter 9.26 / Exhibit tables — verify APN‑specific provisions § 9.26.070
Mobilehome park conversion	:MP requires findings and replacement housing or in‑lieu fees before closure	If your parcel is :MP, expect a zone amendment + required findings (20% replacement formula) § 9.28.140(D)
Cannabis overlay compliance	Additional city cannabis permits and area caps (Area 2 limit = 30)	Confirm Area 1 vs 2 and understand cultivation caps and required non-cultivation commercial space § 9.28.130(C–D)

Plain-English Summary

Arcata’s combining zones are overlays that sit on top of the base zoning and add special rules: environmental buffers for streams, geotechnical review in high‑hazard areas, historic preservation controls, planned‑development flexibility, cannabis business rules, and mobilehome‑park protections. Check the Zoning Map to see if your parcel carries a suffix (for example “:SP” or “:NH”), then read the matching combining‑zone section in Chapter 9.28 and any supplemental chapter (for ESHA see Chapter 9.59) because you must meet both the base‑zone rules and any overlay rules before permits can be approved § 9.28.020; § 9.59.010 file.

Source References

Chapter 9.28, Combining Zones (purpose, applicability, index of overlays) — § 9.28.010 – § 9.28.020
Historic Landmark combining zone — § 9.28.040; Chapter 9.53 Historical Resource Preservation referenced therein
Natural Hazards combining zone — § 9.28.050; Geologic Hazard Review (Chapter 9.62) referenced § 9.62.020 file
Neighborhood Conservation Area and Design Review requirement — § 9.28.060; design review procedures § 9.72.040 file
Planned Development overlay and PD permit reference — § 9.28.070; Planned Development Permit § 9.72.070
Special Considerations tables and SCC/SCI/SCP entries — Chapter 9.26 (various table entries) § 9.26.070
Wetland/Stream protection — Chapter 9.59 (ESHA): § 9.59.010 – § 9.59.050, findings and Notice of Protection § 9.59.090 – § 9.59.100 file
Housing for Homeless combining zone — § 9.28.110; standards cross‑reference § 9.42.200
Cannabis Innovation Zone (:CIZ) — § 9.28.130 (cultivation caps, permit limits) § 9.28.130
Mobilehome Park combining zone (:MP) — § 9.28.140 (allowed uses; rezoning/closure findings)
Zoning Map and district mapping rules — § 9.12.020
Rules of interpretation and code conflict resolution — § 9.10.050

Sources

Retrieved passages

Arcata Zoning Code (Section 9.12.020) High relevance
Arcata Zoning Code (Section 9.42.120) Medium relevance
Arcata Zoning Code Medium relevance
Arcata Zoning Code (Chapter 9.72) Medium relevance
Arcata Zoning Code (Article as) Medium relevance
Arcata Zoning Code (Article 2) Medium relevance
CBC § 181 Medium relevance
Arcata Zoning Code (Title 9) Medium relevance
Arcata Zoning Code (Section 9.42.200) High relevance
Arcata Zoning Code (Section 9.42.040.) High relevance
Arcata Zoning Code (Section 9.42.200) High relevance
Arcata Zoning Code (Chapter apply) High relevance
Arcata Zoning Code (Article may) Medium relevance
Arcata Zoning Code (Chapter 9.28) Medium relevance
Arcata Zoning Code (Chapter 9.62) Medium relevance

Cited sections

Chapter 9.28, Combining Zones (purpose, applicability, index of overlays) — **§ 9.28.010 – § 9.28.020** (Chapter 9.28)
Historic Landmark combining zone — **§ 9.28.040**; Chapter 9.53 Historical Resource Preservation referenced therein (§ 9.28.040)
Natural Hazards combining zone — **§ 9.28.050**; Geologic Hazard Review (Chapter 9.62) referenced **§ 9.62.020** file (§ 9.28.050)
Neighborhood Conservation Area and Design Review requirement — **§ 9.28.060**; design review procedures **§ 9.72.040** file (§ 9.28.060)
Planned Development overlay and PD permit reference — **§ 9.28.070**; Planned Development Permit **§ 9.72.070** (§ 9.28.070)
Special Considerations tables and SCC/SCI/SCP entries — Chapter 9.26 (various table entries) **§ 9.26.070** (Chapter 9.26)
Wetland/Stream protection — Chapter 9.59 (ESHA): **§ 9.59.010 – § 9.59.050**, findings and Notice of Protection **§ 9.59.090 – § 9.59.100** file (Chapter 9.59)
Housing for Homeless combining zone — **§ 9.28.110**; standards cross‑reference **§ 9.42.200** (§ 9.28.110)
Cannabis Innovation Zone (:CIZ) — **§ 9.28.130** (cultivation caps, permit limits) **§ 9.28.130** (§ 9.28.130)
Mobilehome Park combining zone (:MP) — **§ 9.28.140** (allowed uses; rezoning/closure findings) (§ 9.28.140)
Zoning Map and district mapping rules — **§ 9.12.020** (§ 9.12.020)
Rules of interpretation and code conflict resolution — **§ 9.10.050** (§ 9.10.050)
Arcata_ZoningCode.md

Frequently asked questions

What is a combining zone (overlay) in Arcata and where is that defined?

A combining zone (overlay) is a special-purpose zoning suffix applied on top of a base zoning district to add site‑specific standards or limitations. The combining zones are defined and indexed in Chapter 9.28; mapping rules are in § 9.12.020 and the combining-zone purpose and applicability are in § 9.28.010 – 9.28.020 file.

How do I know if my parcel is in an overlay such as :SP or :NH?

Check the City Zoning Map: combining zones are shown as a suffix on the base zone (e.g., RVL:NH). The mapping and interpretation rules are in § 9.12.020 and explained in § 9.28.020 file.

What extra studies are triggered by the Natural Hazards overlay (:NH)?

Projects in :NH typically require geotechnical/geologic reports under the Geologic Hazard Review process (Chapter 9.62); the code explicitly requires compliance with § 9.62.020 when hazards are mapped § 9.28.050 file.

If my lot is in the Stream Protection overlay (:SP), how wide can the buffer be?

Stream protection EBAs are commonly 25 ft in developed reaches and 100 ft in undeveloped reaches, and may expand to 250 ft where significant riparian vegetation exists; the EBA rules are in § 9.59.050(A)(1–3). A variance is possible only with required findings and a Biological Assessment is required for projects affecting ESHA § 9.59.050 .

Do overlays change parking or setback requirements?

Overlays typically layer additional or alternative standards but do not necessarily change base parking or setback tables unless the overlay text explicitly authorizes exceptions (for example :PD can allow exceptions). Always check the overlay chapter and the base zone development tables and Article 3 site standards (setbacks, parking); see § 9.28.070 (PD exceptions) and Article 3 references § 9.30.020 file. For local parking rules consult Arcata Parking.

Does the Historic Landmark overlay (:HL) mean I can’t alter my building?

Not necessarily — alterations are controlled and may require HLC review, special findings, or Council action depending on the designation; the rules are in § 9.28.040 and Chapter 9.53 (Historic Preservation). Owners should expect additional review and possible restrictions on major architectural changes § 9.28.040 .

If I want to build an ADU, do overlays change the ADU rules?

Local ADU provisions still apply, but an overlay may add constraints (for example, ESHA buffers may remove buildable area, :NCA may trigger design review). The Land Use Code overlays must be satisfied in addition to local ADU rules; check Chapter 9.28 and the Arcata ADU rules § 9.28.020 and Arcata ADUs for interactions .

What happens before a permit for work in an ESHA (stream/wetland) becomes effective?

In any discretionary approval affecting an ESHA, the applicant must record a Notice of Protection on the property prior to the permit taking effect; see § 9.59.100 and the findings required in § 9.59.090 .

Can a combining zone be removed or altered for a parcel?

Yes — removing or changing a combining zone requires a rezoning/zone amendment processed under Chapter 9.92 and may require the findings or special conditions listed in the overlay (for example, :MP removals require replacement housing findings) § 9.28.140(D) .

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