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Colusa — Zoning

Zoning under the Colusa local zoning and planning code, with the controlling citations.

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Last reviewed: July 1, 2026

Overview

This page summarizes what the City of Colusa Zoning Ordinance (Title 17) actually says about zoning districts, permitted uses, and the most decision‑relevant dimensional standards. It is drawn from the Colusa Zoning Ordinance text (Title 17). Verify parcel‑specific facts with the City because the official Zoning Map and combining districts control on a lot‑by‑lot basis (§ 3.01) . For practical site work also check local parking requirements and development standards: parking is regulated by Article 29 (§ 29.01 and repeated references) and the district development standards reference the general rules in Article 32 (§ 32.01) .

Use these internal links for related topics you will likely need while applying the ordinance: the city’s pages for parking, development standards, design review, overlay districts, ADUs, and the California Building Standards Code.

How Colusa organizes zoning

  • The ordinance establishes the official City of Colusa Zoning Map and applies the rules in Title 17 to the land areas shown on that map (§ 3.01) .
  • The city uses a set of base districts and a set of special combining districts (e.g., A, B, HD, FP, P, AO, CM) that add or modify standards when combined with a base district (§ 2.01–2.02) .
  • Where the ordinance refers to unspecified numeric standards for a district it defers to the general rules in Article 32 and to specific district articles (for example, many district sections say “the general rules set forth in Article 32 shall apply”) (§ 32.01 referenced repeatedly) .

Below is a district‑by‑district breakdown of the main base districts listed in § 2.01, with the ordinance citations for the controlling subsections.

R-1 — Single‑Family Residence District

  • Purpose: Applied to subdivisions and areas intended for single‑family development (§ 5.01) .
  • Typical permitted uses: one‑family dwellings, private garages, accessory buildings, secondary dwelling units (ADUs) in compliance with applicable standards, small residential care, parks and public uses, agriculture consistent with ordinance limits (§ 5.02) .
  • Key dimensional standards (minimums): Lot area: 8,000 sq ft, Lot dimensions: 80' × 100', Max building coverage: 35%, Front setback: 20 ft, Side setbacks: 5 ft / 10% of lot width (total not more than 15 ft), Rear setback: 20% of lot depth (min 15 ft), Height: 2.5 stories, max 35 ft (§ 5.05) .
  • Where it applies: areas designated R‑1 on the official Zoning Map; unzoned/annexed land defaults to R‑1 until reclassified (§ 3.02) .

R-2 — Two‑Family Residence District

  • Purpose & uses: Intended for duplex/two‑unit residential; the ordinance groups R‑2 with other “R” districts for permitted uses (uses permitted in R‑1 generally apply) (§ 2.01, cross‑references throughout the R articles) .
  • Dimensional standards: R‑2 defaults to the general rules in Article 32 and the R‑4 comparative tables; specific R‑2 numeric minima are not presented separately in the retrieved materials — verify the exact numeric table in Title 17 or with the planning department. Not found in retrieved materials; verify with the jurisdiction.

R-3 — Neighborhood Apartment District

  • Purpose: For small multi‑unit developments and neighborhood apartments (§ 8.01 context) .
  • Uses: Multifamily units, accessory uses, small residential care; major uses (hotels, hospitals, certain public uses) require a major use permit (§ 8.02–8.03) .
  • Key dimensional standards (selected): Lot area: 6,000 sq ft (or 1,500 sq ft/unit for structures with 5+ units), Front setback: 20 ft (reduced to 10 ft if combined with the High Density Combining District “HD”), Rear setback: 20% of lot depth (min 15 ft), Height: up to 4 stories/50 ft, Max coverage: 60% (§ 8.05) .

R-4 — General Apartment District

  • Purpose: Areas where multifamily dwellings are the logical use (§ 8.01) .
  • Uses & standards: Allows R‑1/R‑2/R‑3 uses plus multifamily, SRO, farmworker housing, subject to Article 32 general rules; see § 8.02–8.05 for uses and height/bulk references .

C‑N — Neighborhood Business District

  • Purpose: Serves nearby residential areas with convenience shopping and services (§ 9.01) .
  • Typical permitted uses: Retail (food store, bakery), personal services (barbers, beauty), drugstores, small professional offices, restaurants, and all uses permitted in “R” districts (except dwellings unless a major use permit is secured) (§ 9.02) .
  • Dimensional standards: Front setback: 15 ft, Rear setback: 15 ft, Side setbacks: none except as required, Height: 1 story, max 30 ft, Off‑street parking: as required by Article 29 (§ 9.03) .

C‑G — General Commercial District

  • Purpose: Where general commercial facilities are needed; broader list of commercial uses than C‑N (§ 10.01–10.02) .
  • Typical uses: Uses allowed in C‑N plus hotels, auto sales/repair (with limits), theaters, larger retail and services; certain residential uses require a major use permit (§ 10.02) .
  • Dimensional standards: generally defer to Article 32 or district‑specific rules; some C‑G areas show no lot area/width minimums and rear setbacks may be 5 ft where specified (see § 10.03) .

C‑H — Highway Service Commercial District

  • Purpose: Services for travelling public along highways (restaurants, motels, travel parks) (§ 11.01) .
  • Standards: Front setback: 15 ft, Rear setback: 15 ft, Height: 1 story, max 30 ft, special rules for outdoor advertising signs (size rules) (§ 11.04, § 11.02) .

M‑1 — Light Industrial District

  • Purpose: Light industrial and service uses that do not create offensive conditions; generally follows Article 32 rules (§ 12.01–12.02) .
  • Uses: Uses permitted in C‑G plus warehouses, light manufacturing, feed/fuel yards, laundries, veterinary hospitals, enclosed welding/metal shops when approved (§ 12.02) .
  • Standards: Rear setback: 5 ft, Side setbacks: none except as required, Building height up to 100 ft where specified, parking per Article 29 (§ 12.03) .

M‑2 — General Industrial District

  • Purpose & uses: Heavier industrial uses than M‑1 (lumberyards, concrete batch plants, heavy ceramics, junkyards subject to screening), many uses require enclosure/fencing and/or use permits (§ 13.02–13.03) .
  • Standards: Lot area/coverage/front yard: none, side/rear setbacks: none (except building code), Building height limit: 100 ft, parking: Article 29 (§ 13.04) .

M‑L — Limited Manufacturing District

  • Purpose: Clean and quiet research, light manufacturing and office‑industrial uses (§ 14.01) .
  • Uses: Research labs, small electronics/plastics manufacture, printing, garment and paper product manufacture, offices; utility installations for local service with planning commission review for substations (§ 14.03) .
  • Standards: Lot area: 10,000 sq ft, Front/side/rear setbacks: 20 ft, Height: 2 stories, max 35 ft, parking per Article 29 (§ 14.04) .

P‑D — Planned Development District

  • Purpose: Allows master‑planned projects on sites of sufficient acreage with a tailored permit and design approval; P‑D applications include site maps, elevations and use permits (§ 15.01–15.03) .
  • Uses: All uses permitted in R, C, and M districts when approved by use permit; site‑specific building heights/site area/yard requirements are set in the approved P‑D permit (§ 15.04–15.07) .

P‑F — Public Facilities District

  • Purpose & uses: Public schools, parks, civic centers, public utility facilities, and similar public/quasi‑public uses; some conditional uses (airports, disposal sites) require a use permit (§ 16.01–16.02) .

O‑S — Open Space District

  • Purpose & uses: Preserve natural terrain, recreation, conservation and light agricultural activities (trails, parks, crop/tree farming) (§ 17.01–17.02) .

F‑W — Floodway District

  • Purpose & uses: District listed in § 2.01 as a base district; specific floodway development rules and floodplain administration are set elsewhere in Title 17 (floodplain/development permit rules) (§ 2.01; see floodplain articles) . Specific F‑W numeric standards: Not found in retrieved materials; verify with the jurisdiction.

Mixed‑Use Districts (M‑U‑B, M‑U‑D, M‑U‑M, M‑U‑R)

  • Purpose: Tailored mixed‑use zones for Bridge Street, Downtown, Main Street and Residential mixed use; each has a short purpose statement and a cross‑reference to a Mixed Use districts table (Article 48) (§ 44.01; § 2.01 lists the M‑U types) .
  • Example (Bridge Street M‑U‑B) key numeric standards are explicit: Lot area: 9,600 sq ft (Bridge corridor), Front setback: 5 ft, Rear/side setbacks: 5 ft, Height: 35 ft (Bridge corridor), and parking per Article 29 (§ 44.03) .
  • For the other M‑U districts the ordinance points to the Mixed Use table for permitted uses and standards (see Article 48; mixed‑use table reference in § 44.02) .

Combining districts and special overlays

  • The ordinance authorizes many combining/special districts that modify use and standards when appended to a base district symbol: A (Agricultural), B (Special Building Site), HD (High Density Housing), FP (Flood Plain), CM (Cannabis Manufacturing), AO (Adult‑Oriented), P (Parking), and more (§ 2.02) .
  • Always check the parcel’s full zoning designation (example: R‑1‑HD, C‑G‑FP) on the Zoning Map and read both the base district article and the combining district article for controlling rules (§ 2.02) . See the city’s overlay districts page for practical guidance.

Decision‑relevant standards (quick reference table)

District Typical permitted highlights Key standards (decision items) Code reference
R‑1 One‑family dwellings, ADUs, small public uses Lot area 8,000 sq ft; Front setback 20 ft; Side: 5 ft / 10% lot width; Rear: 20% (min 15 ft); Height 35 ft § 5.02 and § 5.05
R‑3 Neighborhood apartments, multifamily Lot area 6,000 sq ft (1,500/unit for 5+ units); Front 20 ft (10 ft with HD); Height up to 50 ft § 8.02 and § 8.05
C‑N Convenience retail, services Front 15 ft; Rear 15 ft; Height 1 story / 30 ft; Parking per Article 29 § 9.02 and § 9.03
M‑L Light research/manufacturing Lot area 10,000 sq ft; Setbacks 20 ft; Height 35 ft (2 stories) § 14.03–14.04
M‑2 Heavy industrial uses No lot/width minima; Setbacks generally none; Height up to 100 ft § 13.02–13.04
M‑U‑B Bridge St mixed use example Lot area 9,600 sq ft; Front setback 5 ft; Height 35 ft § 44.03

(For parking calculations the ordinance repeatedly directs readers to Article 29 — check parking and Article 29 text in Title 17 for exact ratios) .

Checklist

  • Confirm the parcel’s zoning symbol on the official Zoning Map (Zoning Map adoption and map amendment rules: § 3.01–3.03) .
  • Read the base district article for permitted uses and minimum height/bulk/space rules (e.g., § 5.05 for R‑1) .
  • Check whether any combining district (A, B, HD, FP, CM, P, AO, etc.) is appended to the parcel and read that article (see § 2.02) .
  • Confirm parking requirements in Article 29 and whether a P (special parking) combining district or variance applies (§ 29.* references throughout) .
  • If the proposal triggers design or planned development review, read P‑D rules and prepare required maps/elevations (P‑D application content: § 15.03–15.07) .
  • For ADUs: verify local ADU standards in the ADU article and minimums (see Title 17 ADU provisions and the city's ADU page) — ADU sizing/height rules are codified in Article 49/ADU sections (§ 49.08–49.10) .
  • If your use is conditional/major/minor, identify the correct permit path (planning director vs. planning commission) as stated in district use tables (e.g., § 9.03, § 8.03) .

Risks & Ambiguities

Issue Why it matters What to verify
Boundary uncertainty (map vs. lot lines) Zoning boundary ambiguity changes the controlling district and permitted uses (§ 3.02) Verify the parcel on the official Zoning Map; if unclear, request a written boundary determination from the planning director (§ 3.02)
Combining/overlay rules Combining districts (e.g., HD, FP, CM) add or override standards — missing them can lead to noncompliance (§ 2.02) Check the full zoning symbol on the map and read both the base district and combining district articles; “Verify with the jurisdiction.”
Article 32 general rules referenced but not duplicated Many district sections defer to Article 32 for details; neglecting Article 32 can miss yard/coverage exceptions (§ 32.01 references) Read Article 32 in full; if a numeric standard is not stated in the district article, the Article 32 rule controls.
ADU specifics vs. state law Local ADU rules exist, but state ADU law also constrains what the city can require; conflict can occur between local ADU text and state law (§ 49.x and state code) Consult the ADU section of Title 17 and compare with California ADU law. Verify with the planning department.
Parking defined in Article 29 only by reference Most district sections just say “Off‑street parking: as required by Article 29” — exact stall counts matter for approvals (§ 9.03, § 12.03, etc.) Pull Article 29 for the exact parking ratios; consider whether a P combining district or variance is needed.
Cannabis and adult‑oriented special rules Cannabis and adult‑oriented uses have specific limiting rules and permit caps; they require regulatory permits and council/commission review (Article 21.5, Article 27) If your project relates to cannabis or adult‑oriented businesses, read those articles carefully and confirm local caps/locational limits.

Plain‑English summary

Colusa’s Zoning Ordinance (Title 17) divides the city into named districts (e.g., R‑1, C‑N, M‑L, M‑U‑B) with each district listing allowed uses and giving the major numeric rules (lot area, setbacks, height, coverage). Many district sections also say “follow the general rules in Article 32” and point to Article 29 for parking; always check the parcel’s full zoning symbol on the official Zoning Map and read both the base district article and any combining/overlay article that applies (§ 3.01–3.03; § 2.02) .

Source References

  • Zoning districts list and combining districts: § 2.01–2.02 .
  • Zoning Map adoption and boundary interpretation: § 3.01–3.03 .
  • R‑1 district uses and standards: § 5.01–5.05 .
  • R‑3 / multifamily rules: § 8.01–8.05 .
  • C‑N district uses and standards: § 9.01–9.03 .
  • C‑G, C‑H, M‑1, M‑2, M‑L district articles and standards: § 10.x, 11.x, 12.x, 13.x, 14.x .
  • Planned Development (P‑D) application requirements and flexibility: § 15.01–15.08 .
  • Mixed‑Use example (M‑U‑B Bridge Street standards): § 44.01–44.04 .
  • Article 29 references for parking appear throughout (district articles: e.g., § 9.03(f), § 12.03(f)) .
  • ADU sizing/height rules and ADU article references: Article 49 (e.g., § 49.08–49.10) .
  • Floodplain administration and floodway rules referenced in Title 17 (flood articles): see floodplain/floodway sections in Title 17 (flood sections included in ordinance text) .

If you want copies of the exact ordinance language or the official Zoning Map image excerpted for a particular parcel, I can pull the specific ordinance subsections and highlight the lines that apply to your address — tell me the APN or street address and I will extract the controlling § references.

Sources

Retrieved passages

  • Colusa Zoning Code (§ 2) High relevance
  • Colusa Zoning Code (Article 29.) High relevance
  • Colusa Zoning Code (Article 29.) High relevance
  • Colusa Zoning Code (article may) High relevance
  • Colusa Zoning Code (article shall) High relevance
  • Colusa Zoning Code (Article 2.) High relevance
  • California Building Code (Article 29.) High relevance
  • California Building Code (Article 29.) High relevance
  • Colusa Zoning Code (Article 32) High relevance
  • California Building Code (Article 29.) High relevance
  • Colusa Zoning Code Medium relevance
  • California Building Code (Article 29.) Medium relevance

Cited sections

Frequently asked questions

What can I build on an R‑1 lot in Colusa?

You can build a one‑family dwelling, accessory buildings and uses, secondary dwelling units (ADUs) subject to the ADU rules, small residential care and certain public uses listed in § 5.02; numeric development standards (lot area, setbacks, height) are in § 5.05 .

What are Colusa setback requirements for R‑1 and C‑N?

For R‑1 the ordinance sets the front setback at 20 ft; side setbacks 5 ft on one side and 10% of lot width on the other (total not more than 15 ft); rear 20% of lot depth (min 15 ft) (§ 5.05) . For C‑N the ordinance lists front 15 ft; rear 15 ft; side yard none except as required (§ 9.03) .

Do I need design review in Colusa?

Many projects (especially in P‑D / Planned Development, public civic projects, and some downtown/mixed‑use areas) require planning commission or design review; the P‑D article describes required plan submittals and review standards (§ 15.03–15.07) and the ordinance’s design procedures are referenced in Article 32 and the P‑D article — verify with the planning department for your specific parcel and project type (§ 15.03) .

Where do I find the official Zoning Map and how are boundary disputes handled?

The Zoning Map is adopted as part of the ordinance and is controlling (§ 3.01). If there is uncertainty about a district boundary, Title 17 provides rules (street lines, lot lines) and authorizes the planning director to determine the boundary in writing (§ 3.02–3.03) .

Are ADUs allowed in Colusa and what are the size limits?

ADUs are allowed in residential districts; local ADU provisions set minimum sizes and height limits (see Article 49 ADU rules: maximum heights and minimum interior sizes, e.g., § 49.08–49.10) and note that ADUs must comply with lot coverage and architectural compatibility requirements (§ 49.08–49.10) .

What is the rule for uses that are not listed (special or new businesses)?

The ordinance contains use permit categories (minor or major) for uses the code does not list. If a use is not expressly permitted, it may require a use permit and findings by the planning commission or director; see the district “uses requiring a major use permit” lists (example: § 9.03 for C‑N uses requiring permits; § 8.03 for R‑3) and the general use permit articles in Article 32 (§ 8.03; § 9.03) .

What happens if my property is in a floodplain or the Floodway District?

Floodplain and floodway rules are included in the ordinance and require development permits and compliance with floodplain elevation/proofing standards; floodplain administration and development permit requirements are set in the Title 17 flood sections and related articles (see floodplain/floodway articles) — check the flood articles and § 39.04 for development permit specifics for flood hazard areas; verify whether F‑W or FP combining districts apply to the parcel (§ 39.x and § 2.02) .

How do combining districts (like HD or FP) change the rules?

A combining district appended to a base district adds or modifies regulations; the ordinance states that combining district regulations apply in addition to the base district rules, so you must read both the base district article and the combining district article (see § 2.02) .

If my use was legal before but doesn't conform now, can I keep operating?

The ordinance has nonconforming use and amortization provisions (see Article on nonconforming uses and specific amortization rules for adult‑oriented businesses in Article 27). Some nonconforming uses may continue under limits or may be amortized — review the nonconforming uses article for the specific rules and timelines. If you need the precise nonconforming‑use section citation for your type of use, tell me the use and I will extract the exact § .

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