Colusa County Zoning, Planning & Building Codes

Last reviewed: July 6, 2026

Overview

This page orients you to how zoning and development are regulated in Colusa County’s unincorporated areas. Colusa County’s zoning code (which applies only outside of incorporated cities) was not included in the retrieved materials. The only ordinance returned is the City of Colusa’s zoning ordinance, which—by its own text—applies solely within the incorporated City of Colusa and not to the County’s unincorporated areas (§ 1.06; see “Application”).
Where the County’s specific sections could not be confirmed below, this page flags the gap and points you to related topics like Colusa County Zoning, Colusa County Development Standards, Colusa County Parking, and Colusa County Design Review for topic-level guidance.

Most important takeaway: the retrieved ordinance is the City of Colusa’s, not the County’s. It expressly applies only to the incorporated “City of Colusa” (§ 1.06). Confirm the County’s code text before relying on any city-only standards in unincorporated areas.

How Colusa County’s code is organized

• Not found in retrieved materials. Verify with the County the exact code title (e.g., “Title X – Zoning” or “Title X – Land Use and Development”) and where the zoning map, procedures, and base district standards are codified.
• The only retrieved text is the City of Colusa’s zoning ordinance (Appendix A – Zoning). It opens with findings and adoption, then lays out districts, a map, definitions, district standards, parking, permit procedures, and enforcement (§§ 1.02–1.06; Article 2; Articles 29, 33–37). These sections do not govern unincorporated areas.

If you’re navigating the County’s unincorporated rules, start from Colusa County Land Use and Colusa County Zoning to locate the controlling Title/Chapters and the County’s official zoning map.

Zoning district families

• Not found in retrieved materials for unincorporated Colusa County.
• Caution: the district list we do have (e.g., R-1, C-G, M-1, and mixed-use districts like M-U-B) is from the City of Colusa’s ordinance (§ 2.01) and is city-only, not for unincorporated areas. Do not rely on these designations in the County’s unincorporated areas.
• For County-specific base districts and overlays, see Colusa County Zoning and Colusa County Overlay Districts.

Citywide development standards

This section summarizes where such rules typically live and what to look for; however, County-specific numbers and tables were not retrieved.

• Setbacks, height, lot coverage, FAR, and lot dimensions: Not found in retrieved County materials.
  • Do not use the City of Colusa standards (e.g., sample city-only standards such as a 20 ft front setback or 35 ft height in certain city districts) for unincorporated sites. Those examples come from City districts (e.g., R-2, C-H) and are not applicable to County areas (§§ 6.05; 11.04).
• Parking: Countywide minimums and adjustment provisions not found. City-only parking tables (Article 29) were retrieved; do not apply these in the County (§ 29.02).
• Design standards and design/discretionary review: Not found for the County. For process types conceptually similar to “use permits” or “variances,” the City’s procedures (Articles 33–34) are city-only and cannot be used for County properties (§§ 33.01; 34.01). See Colusa County Design Review, Colusa County Variances and Exceptions, and Colusa County Nonconforming Uses for topic guidance.

Specific plans & overlays

• Not found in retrieved County materials.
• Floodplain/other hazard overlays: The only floodplain management text retrieved is again City-specific (City of Colusa Floodplain provisions; not County) (§ 39.03). Do not apply in unincorporated areas. Verify County floodplain and other overlays via Colusa County Overlay Districts.

Building permits & review

• Building code: In unincorporated Colusa County, building permit requirements are governed by the statewide California Building Standards Code (also known as “Title 24”), as locally adopted. County-specific adoption amendments and submittal checklists were not retrieved here—confirm with the County’s Building Division.
• Planning permits (e.g., use permits, variances, design review): County procedures were not retrieved. The processes we do have (e.g., City-major/minor use permits and variances) are City of Colusa-only and cannot be used for County sites (§§ 33.01; 34.01).

State housing law in Colusa County

State housing laws apply in unincorporated areas, even when a local ordinance is silent. Below are statewide requirements relevant in every California county; local County chapters implementing them were not retrieved.

• California ADU law:
  • Ministerial review and timing. Agencies must approve or deny a complete ADU/JADU application within 60 days when a dwelling exists on the lot (Gov. Code §§ 66317, 66320, 66335).
  • Minimum allowance. Local rules cannot preclude at least one 800 sq ft ADU with 4 ft side/rear setbacks and no minimum lot size beyond this baseline (Gov. Code § 66321(b)(3)).
  • Heights. Detached ADUs: base 16 ft; up to 18 ft near qualifying transit or on lots with multifamily/multistory housing; attached ADUs up to 25 ft or the primary dwelling’s height if lower (Gov. Code § 66321(b)(4)).
  • Parking limits. Multiple state exemptions restrict when localities can require ADU parking (Gov. Code § 66322(a)); conversion and small (<750 sf) units are exempted in many cases.
• Density bonus and other California housing laws: State density bonus law (Gov. Code § 65915 et seq.) applies countywide. A City density bonus chapter was retrieved (City-only) and confirms alignment with state statutes, but County-implementing sections were not retrieved (§ 41.01). Verify the County’s implementing chapter.

Information Gaps

Because the County’s zoning title and implementing chapters were not included in the retrieved files, the following remain unconfirmed for unincorporated Colusa County:

• The exact code title and numbering for zoning and land use procedures (e.g., “Title 17 Zoning” vs. another title).
• The County’s base zoning districts and official zoning map reference.
• Countywide numeric development standards (setbacks, height, lot coverage/FAR) by district.
• County overlay districts (e.g., floodplain, airport, historic/cultural) and their standards.
• County-specific permit procedures for use permits, site/design review, variances, and nonconformities.
• Any County-specific ADU/JADU standards beyond state minimums.

Please verify the above with the County. The retrieved ordinance applies only to the incorporated City of Colusa and expressly not to the unincorporated areas (§ 1.06).

Source References

• City of Colusa Zoning Ordinance (Appendix A – Zoning): Application limited to the incorporated city; not the County (§ 1.06).
• City of Colusa district list (city-only; do not apply in County) (§ 2.01).
• City parking provisions (Article 29; city-only; do not apply in County) (§ 29.02).
• City permit procedure examples (Articles 33–34; city-only; do not apply in County) (§§ 33.01; 34.01).
• City floodplain provisions (city-only; do not apply in County) (§ 39.03).
• State ADU timing/ministerial processing and development baselines (Gov. Code §§ 66314, 66317, 66320, 66321, 66322, 66335) summarized in 2025 California ADU guidance.