Bolthole Index

Colusa County, California

Building permits, zoning and land rules in Colusa County, California

44Index Score / 100
#26 of 58 in California

Unincorporated Colusa County, California requires building permits for new buildings and many alterations, and every application goes through the county's online permit portal12. County zoning covers unincorporated land; the cities of Colusa and Williams run their own zoning inside city limits345. Septic systems and wells outside city sewer come from Colusa County Environmental Health, not the Building Department67.

At a glance

Building permit
Required for new buildings and many additions, renovations and building-system projects1
Zoning
Yes in unincorporated areas by district; the cities of Colusa and Williams zone their own land3845
Septic
Environmental Health requires a permit to construct, reconstruct or repair an onsite system910
RV living
No permanent RV residence; temporary occupancy during home construction requires a Temporary Use Permit11
Tiny home
A qualifying park-trailer tiny home is an approved accessory dwelling unit once utility, foundation and design conditions are met1213
Manufactured home
Permitted in listed residential and agricultural zones; temporary placement requires a Temporary Use Permit1415
Owner-builder
Available conditionally; the county permit form requires an owner-builder declaration16
Water well
A county permit is required for a new well, modifications or abandonment7

Who to call

Building permits

Colusa County Building Department

Building permit applications, plan and code-compliance review; the coordinated review also sends plot plans to Planning for zoning and setbacks

(530) 458-0481

1213 Market Street, Colusa, CA 95932

Online permits →

Septic permits

Colusa County Environmental Health

Onsite wastewater treatment systems and water-well permits and inspections

(530) 458-0888

1213 Market Street, Colusa, CA 95932

Online permits →

Roads & driveways

Colusa County Public Works

County-road encroachment and transportation permits, flood control, roads and bridges

(530) 458-0466

1215 Market Street, Colusa, CA 95932

Floodplain permits

Colusa County Public Works — Floodplain Permits

Floodplain permits and flood elevation certificates

(530) 458-0466

Contact details are copied from each office’s official page and were checked against it on October 16, 2026.

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Do you need a building permit in Colusa County, California?

Yes. Colusa County requires permits for new residential, commercial and industrial buildings, additions, decks, pools, water heaters, patio covers, conversions, expansions, reroofing, electrical and plumbing systems, heating and air-conditioning systems, and structures over 120 square feet; the county says that list is not exhaustive1. The 2025 California Building Standards Code became effective January 1, 2026 and applies to building-code work the county administers17. After issuance, county inspectors verify that work matches the permit, applicable codes and approved plans18. At completion, the inspector signs the job card, and the county can issue a Certificate of Occupancy or Notice of Completion upon request19. An owner-builder option can exempt a qualifying owner from contractor licensing, but it does not remove the county permit or inspection requirements1620.

Who issues building permits in Colusa County, and how do you reach them?

The Colusa County Building Department receives building applications through the county's online permit portal and reviews project plans for code compliance21. The coordinated review sends the plot plan to Planning for allowed-use and setback review, Environmental Health for wells and waste disposal, the applicable fire district for State Fire-Safe review, and Public Works for county-road encroachments, flood hazards and significant grading2. The Building Department is at 1213 Market Street in Colusa and can be reached at (530) 458-048121. A complete plan set may need electrical and plumbing plans, truss and energy calculations, a plot plan, and applicable sprinkler and solar plans2. Public Works publishes separate fees: a county-right-of-way encroachment permit costs 3% of the estimated work, weekend or holiday inspections are billed separately, and a flood-zone development permit has no fee22.

Does Colusa County have zoning, and what does it mean for setbacks and lot size?

Yes. The Colusa County Zoning Code applies to all unincorporated land in Colusa County3. Inside city limits, Colusa administers its own zoning ordinance4 and Williams sets zoning under its own Title 175; the county's rules below do not apply there, and we could not confirm who issues building permits in either city, so ask the city. The county publishes a countywide map plus maps for named communities and unincorporated parts of Colusa and Williams23. Planning reviews whether a proposed use is allowed and whether the plot plan meets setbacks21. Minimum parcel size is 80 acres in F-A and U-C, 40 acres in E-A and 10 acres in U-T and A-T24, and 20 acres in A-T-2025. In those agricultural districts a home (a non-agricultural structure) needs 25-foot front and rear setbacks, and side setbacks of 25 feet in F-A, E-A and U-C or 20 feet in U-T and A-T26. Non-agricultural structures may reach 30 feet unless a variance is obtained27. Manufactured or mobile homes are permitted in listed residential and agricultural zones14. A second unit must have at least 150 square feet; we could not confirm a minimum size for primary homes28. A second unit may be up to 1,200 square feet, or 2,500 in the agricultural districts F-A, E-A, U-C, U-T and A-T28.

How do septic permits work in Colusa County?

Colusa County Environmental Health administers onsite wastewater treatment systems in unincorporated areas for ordinary systems designed at 10,000 gallons per day or less9. A permit is required before constructing, reconstructing or repairing a septic system, and site evaluation is part of approval10. Only 3.9% of county soils avoid a severe USDA limitation for a conventional drain field, so test the actual homesite early and budget for a design beyond a standard trench system if the evaluation requires one29. A property with an approved available sanitary sewer within 200 feet must connect when the right-of-way and required sewer-authority and LAFCO approvals can be obtained30. Surface-discharge approaches such as surface irrigation or evaporation ponds are not authorized as county OWTS, and alternative systems carry installation, operating, monitoring and inspection requirements31. Environmental Health is at 1213 Market Street in Colusa and can be reached at (530) 458-088832.

Can you live in an RV or tiny home on your land in Colusa County?

You cannot use an RV as a permanent residence in unincorporated Colusa County; temporary RV occupancy during home construction requires a Temporary Use Permit and must fit the circumstances allowed by county code11. We could not confirm a general private-land camping allowance outside that construction pathway, so ask Planning before placing or occupying an RV. Colusa County's tiny-home ordinance, adopted December 14, 2021, treats a park-trailer tiny home outside an approved mobile-home or special-occupancy park as an accessory dwelling unit, but only if all of these are met: utilities connect to county-approved systems under an issued county permit; the wheels and tongue are removed; a county-approved foundation with its own building permit supports it; and the exterior looks like a house rather than an RV, with matching skirting, to the Community Development Director's satisfaction1213. A tiny home on wheels that cannot meet those conditions is not covered by that pathway, so confirm the classification with Planning before buying one33. Manufactured and mobile homes are allowed in listed residential and agricultural districts, while temporary mobile homes require a Temporary Use Permit1415.

Building a home in Colusa County: what are the steps?

  1. Ask Planning to verify the parcel's zoning district, allowed residential use, setbacks and any required land-use approval before finalizing plans21.
  2. Start the Environmental Health site evaluation and septic permit if public sewer is unavailable, because poor drain-field ratings make early soil work especially valuable1029.
  3. Apply to Environmental Health before drilling, modifying or abandoning a water well7.
  4. Prepare the building plans and a plot plan showing buildings, utilities, sewage disposal, streets, easements and access234.
  5. Submit the complete building application through the online permit portal21.
  6. Coordinate with Public Works if the project affects county right-of-way, grading or a flood hazard, and obtain a Caltrans encroachment permit if access enters a state highway3536.
  7. Keep approved plans onsite and complete the required inspections through final sign-off18.

What should you check before buying land in Colusa County?

First determine whether the parcel is unincorporated or inside Colusa or Williams, then use the county's published maps and have the responsible planning office confirm the exact zone, allowed dwelling type, setbacks and parcel status238. A land division requires county subdivision review in unincorporated Colusa County37. Check the FEMA flood map, which the county says covers the unincorporated areas, and ask Public Works about floodplain permits and elevation certificates before choosing a building pad; Public Works also reviews every building-permit plot plan for flood hazards, and the flood-zone development permit carries no fee3839. The county's pages do not spell out construction standards for flood zones, so get those from Public Works in writing38. Verify legal access too: Public Works issues and inspects permits for work in county right-of-way, while access onto a state highway needs Caltrans approval3536. Wells require a county permit, and severe drought occurs in about 41% of years740. Septic feasibility is a major purchase contingency because only about 4% of soils avoid severe limits for a conventional drain field29.

Watch-outs

  • A shed or similar structure over 120 square feet is specifically listed as permit-required, but the county's list is not exhaustive; ask the Building Department before beginning smaller work too1.
  • Permanent RV residence is not allowed, and temporary occupancy during home construction requires a Temporary Use Permit11.
  • A nearby sewer can change the septic plan: qualifying structures within 200 feet of approved available sanitary sewer must connect when the ordinance's access and approval conditions are met30.
  • Public Works says county subdivision standards are being updated and may change before revised standards are posted, so confirm the current version before designing a land split37.
  • The county's tiny-home pathway applies to park trailers outside approved parks, and the Community Development Director judges the exterior and skirting, so ask Planning to confirm a specific unit before you buy13.

Sources

  1. Building Permits, quoted and re-checked
  2. Building Permits, quoted and re-checked
  3. Colusa County Zoning Code, quoted and re-checked
  4. Colusa: City of Colusa zoning information (Colusa County), quoted and re-checked
  5. Williams: Williams Code 17.01.030 Permitted; limited; conditional; and temporary uses (Colusa County), quoted and re-checked
  6. Colusa County Onsite Wastewater Treatment Systems Ordinance (2026 county census)
  7. Appendix G Drainage, Hydrology, and Water Quality Analysis, quoted and re-checked
  8. Zoning Code | Colusa County, CA, quoted and re-checked
  9. Colusa County Onsite Wastewater Treatment Systems Ordinance, quoted and re-checked
  10. Colusa County Onsite Wastewater Treatment Systems Ordinance, quoted and re-checked
  11. countyofcolusaca.gov, quoted and re-checked
  12. Ordinance No. 819 — Tiny Homes, quoted and re-checked
  13. Ordinance No. 819, quoted and re-checked
  14. Colusa County Zoning Code — Zoning Classifications, Allowed Uses, and Development Standards, quoted and re-checked
  15. Colusa County Zoning Code: Zoning Classifications, Allowed Uses, and Development Standards, quoted and re-checked
  16. Building Permit Form, quoted and re-checked
  17. Building | Colusa County, CA - Official Website, quoted and re-checked
  18. Building Permits, quoted and re-checked
  19. Building Permits — Final Approval, quoted and re-checked
  20. Owner-Builder Responsibilities (California statewide rule), quoted and re-checked
  21. Colusa County Building Department (countyofcolusaca.gov)
  22. Fee Schedule, quoted and re-checked
  23. Zoning Code, quoted and re-checked
  24. Colusa County Zoning Code — Zoning Classifications, Allowed Uses, and Development Standards, quoted and re-checked
  25. Colusa County Zoning Code, quoted and re-checked
  26. Zoning Code, quoted and re-checked
  27. Zoning Code, quoted and re-checked
  28. Zoning Code | Colusa County, CA - Official Website, quoted and re-checked
  29. Share of soils USDA rates "not limited" for a conventional septic drain field (SSURGO). A strict rating: the median county is about 6% and a tenth of counties are 0%, so a low figure means most lots need a site evaluation or an engineered system, not that septic is impossible. Cite it only with that caveat: Bolthole Index county data
  30. Colusa County Onsite Wastewater Treatment Systems Ordinance, quoted and re-checked
  31. Colusa County Onsite Wastewater Treatment Systems Ordinance, quoted and re-checked
  32. Colusa County Environmental Health (countyofcolusaca.gov)
  33. Ordinance No. 819: Tiny Homes, quoted and re-checked
  34. Building Permits, quoted and re-checked
  35. Colusa County Public Works (countyofcolusaca.gov)
  36. Encroachment Permits | Caltrans (California statewide rule), quoted and re-checked
  37. Subdivision Standards, quoted and re-checked
  38. Floodplain Development Permits | Colusa County, quoted and re-checked
  39. Colusa County Public Works — Floodplain Permits (countyofcolusaca.gov)
  40. Share of years in severe drought: Bolthole Index county data

Written October 16, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

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Compared with neighboring counties

Like all 6 of its neighbors, Colusa County has countywide zoning.

RuleColusa CountySutter CountyLake CountyGlenn CountyYolo CountyYuba CountyNapa County
Building permitRequiredRequiredRequiredRequiredRequiredRequiredLimited
County zoningYesYesYesYesYesYesYes
Septic permitsCounty Env. Health Div.County Development ServicesCounty Health Services Dept.County Env. HealthCounty Env. Health Div.County Env. HealthCounty Env. Health Div.

County locator

Colusa County in California

44
County map
Colusa County highlighted among the California counties · colored by Index score

How Colusa County scores

Seclusion48100% ev.
Self-Sufficiency43100% ev.
Admin Boringness41100% ev.
Durability22100% ev.
Property Autonomy56100% ev.
Carry Cost56100% ev.

Evidence strength: 100%. This reports direct-source completeness and fallback use; it is separate from the score and is not a confidence interval. How it works →

$380kTypical home
0.7%Property tax
$11,119Land / acre
24.8"Annual rain
40.8% of yrsSevere drought
35.6 / yr (+20.8)Mid-century 100°F days
87.9 daysMid-century dry spell
1.56" (+6.8%)Mid-century 1-day rain
1.08×Wildfire change factor
100%Forward climate coverage
$1,239Home insurance / yr
2.2% / yrInsurance growth
1.06%Nonrenewal rate
county median (2+ published ZIPs)Insurance basis
17,055People within 30 min
5,313,539People within 2 hr
16,248Radius comparison (15 mi)
19.2People / sq mi
19.2%Federal land
61.4%Land at 15% slope or less
3.9%Soils rated "not limited" for septic (strict USDA rating)
28,138 acWorkable land screen
31.7%Wooded land
23 tonsBiomass / forest ac
61.6°FAvg temp

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Cities and towns in Colusa County

Inside a city or town, that city usually issues building permits and sets zoning; the county’s rules above cover unincorporated land. Septic, wells and floodplain rules usually stay with the county or state everywhere.

Answers from the rulebook for Colusa County

What the ordinances and state agencies actually say — one answer per question, each quoted from the official source and independently re-checked.

Colusa County rules

  • Building permitRequired

    Construction work administered through the Colusa County Building Department.

    • The official handout states the listed permit-required activities are not exhaustive.
    • The source directs applicants to contact the Building Department to determine whether a permit is needed.
    • The listed examples include new residential, commercial, and industrial buildings; additions; residential work; renovations; electrical and plumbing systems; heating and air-conditioning systems; and structures over 120 square feet.

    structure area threshold: > 120 sq. ft. (The source states permits are required for any structure over 120 sq. ft.)

    “Permits are required for the following, but not limited to:  New buildings (Residential, Commercial & Industrial).  Addition(s) to existing structure  Residential work (decks, pools, water heaters, patio covers, etc.)  Renovations (conversions, expansions, re-roofing, etc.)  Electrical and Plumbing systems  Heating & Air Conditioning systems  Any structure over 120 sq. ft.”
  • Owner-builder exemptionConditional

    An owner applying for a Colusa County building permit and claiming exemption from the California Contractor's State License Law.

    • The declaration must be made under penalty of perjury.
    • The owner may perform the work personally or through employees whose wages are their sole compensation, but the structure must not be intended or offered for sale.
    • Alternatively, the owner may exclusively contract with licensed contractors.
    • The form also provides an option to identify another exemption under a specified Business and Professions Code section and reason.
    • The permit form separately requires workers' compensation declarations.
    “I hereby affirm under penalty of perjury that I am exempt from the Contractor's State License Law for the following reason: [ ] I, as owner of the property, or my employees with wages as their sole compensation, will do the work, and the structure is not intended or offered for sale. [ ] I, as owner of the property, am exclusively contracting with licensed contractors to construct the project.”
  • Building code adoptedAdopted

    The 2025 California Building Standards Code applies to building-code operations administered by Colusa County.

    • The source states that the code was published on July 1, 2025.
    • The source states that the code became effective January 1, 2026.

    code edition: 2025 California Building Standards Code · published date: 2025-07-01 · effective date: 2026-01-01

    “Colusa County is operating under the 2025 California Building Standards Code (Cal. Code Regs., Title 24) published on July 1, 2025, with an effective date of January 1, 2026.”
  • InspectionsRequired

    Projects for which Colusa County has issued a building permit.

    • On-site inspections are required to verify conformity with the permit, applicable codes, and approved plans.
    • The permit must be posted at the job site and project plans must be on site for the building inspector.
    • Inspection requests must be made two days before the inspection date according to the handout; the current inspection-information page requests inspections at least three to five days in advance.
    • The inspection-information page requires approved and stamped plans and specifications on site if applicable, the building permit number, and the building location.
    • Failure to comply with the current inspection-information requirements results in a $47-per-hour re-inspection fee, payable before another inspection is scheduled; additional fees may be charged under the county building code.

    inspection request lead time: 2 days (The official inspection-information webpage currently requests three to five days in advance.) · re-inspection fee: 47 USD per hour (Additional fees may be charged under the county building code.)

    “On-site inspections will be required to make certain the work conforms to the permit, appropriate codes and approved plans.”
  • Certificate of occupancyLimited

    Completed projects subject to Colusa County building inspection and final approval.

    • The building inspector must sign the project job card as complete, indicating compliance with code requirements.
    • A Certificate of Occupancy or a Notice of Completion is issued upon request, so the source does not establish a universal mandatory certificate requirement for every project.
    “At the completion of the project, the building inspector will sign the project job card as complete, indicating compliance with code requirements. A Certificate of Occupancy or a Notice of Completion will be issued upon request.”
  • County-wide zoningPresent

    County zoning regulation of land uses, subdivisions, and development on unincorporated lands within Colusa County.

    • The County Zoning Code does not establish county zoning jurisdiction over incorporated municipalities.
    • The cited code states that the geographical jurisdiction includes all unincorporated lands within Colusa County.
    “The geographical jurisdiction for this Zoning Code includes all unincorporated lands within Colusa County.”
  • Local zoningVaries (with conditions)

    Aggregate local zoning across Colusa County: County zoning applies in unincorporated areas, while incorporated municipalities may administer their own zoning ordinances.

    • The County Zoning Code applies to unincorporated lands within Colusa County.
    • The City of Colusa has a separate zoning ordinance intended to apply within the incorporated area of the City of Colusa.
    • The applicable zoning authority and rules depend on whether land is unincorporated or within an incorporated municipality.
    “The Zoning Plan is intended to apply to all private, public, quasi-public, institutional, and public utility properties and all other lands, buildings and structures within the incorporated area of the City of Colusa.”
    One more reviewed finding on this topic
    • Varies (with conditions) — Aggregate local zoning within Colusa County; zoning controls vary by mapped county zoning district and by incorporated or unincorporated community, rather than representing one uniform rule for every parcel.
      “Specific zoning districts separate land uses which might be incompatible with each other. Zoning does this by directing industrial, commercial, residential, and other land uses to specified lands where similar uses will be located.”
  • Zoning districtsPublished

    Colusa County zoning code and published zoning maps for county-regulated unincorporated areas.

    • The County page states that the zoning code was adopted on August 26, 2014.
    • Published maps include a countywide map and area maps for Arbuckle, College City, Colusa (Unincorporated), Grimes, Maxwell, Princeton, Stonyford and Lodoga, and Williams (Unincorporated).
    • Incorporated municipalities may administer their own land-use rules; this claim is limited to County-regulated areas.

    zoning code adoption date: August 26, 2014

    “Read Colusa County’s Zoning Code adopted on August 26, 2014.”
  • Minimum dwelling sizeSpecified

    Second dwelling units governed by Colusa County Zoning Code section 44-4.10.060 in unincorporated Colusa County.

    • The minimum floor area is 150 square feet or the minimum efficiency-unit size identified by California Health and Safety Code section 17581.1, whichever is greater.
    • A second unit must comply with all development and design standards of the Zoning Code applicable to the primary dwelling, except as otherwise provided in section 44-4.10.060.
    • The section also provides that the zoning classification minimum lot area per dwelling unit does not apply if minimum building-site requirements are met.
    • The second unit floor area may not exceed 1,200 square feet, except on agricultural classifications F-A, E-A, U-C, U-T, and A-T, where it may be up to 2,500 square feet.
    • Detached second units require a minimum three-foot side setback, eight-foot rear setback, and ten-foot separation from buildings on the same lot.
    • Attached second units require a minimum three-foot side setback, eight-foot rear setback, and ten-foot separation from buildings on the same lot, and must meet the same setbacks as the primary residential dwelling in the zoning classification.
    • Access to the second unit must be separate from access to the primary residential dwelling.

    minimum floor area: >= 150 square feet (The minimum efficiency-unit size identified by Health and Safety Code section 17581.1 applies if greater.) · maximum floor area: <= 1200 square feet (Agricultural classifications F-A, E-A, U-C, U-T, and A-T may have up to 2,500 square feet.)

    “The minimum floor area of the second unit shall be no less than 150 square feet or the minimum efficiency unit size identified by Health and Safety Code Section 17581.1, whichever is greater.”
  • Minimum lot sizeDistrict specific (with conditions)

    Parcels in Colusa County agricultural zoning classifications F-A, E-A, U-C, U-T, and A-T; the A-T table classification is further identified in the code as A-T-10.

    • Allowed uses and associated structures must comply with the agricultural-zone development standards and other applicable Title 44 requirements unless a variance is obtained under Section 44-1.80 (Types of Permits).
    • The code table identifies minimum parcel size by zoning classification: F-A 80 acres, E-A 40 acres, U-C 80 acres, U-T 10 acres, and A-T 10 acres.

    F-A minimum parcel size: 80 acres · E-A minimum parcel size: 40 acres · U-C minimum parcel size: 80 acres · U-T minimum parcel size: 10 acres · A-T-10 minimum lot size: 10 acres

    “Development Standards – Foothill Agriculture (F-A), Exclusive Agriculture (E-A), Upland Conservation (U-C), Upland Transition (U-T), and Agricultural Transition (A-T) [...] Minimum Parcel Size 80 ac 40 ac 80 ac 10 ac 10 ac”
    One more reviewed finding on this topic
    • Specified — Parcels in the Colusa County Agricultural Transition A-T-20 zoning classification.
      “The A-T zone includes A-T-10, which allows for a minimum 10-acre lot size, and A-T-20, which allows for a minimum 20-acre lot size.”
  • SetbacksDistrict specific (with conditions)

    Agricultural and non-agricultural structure setbacks in the county agricultural zoning districts F-A, E-A, U-C, U-T, and A-T in unincorporated Colusa County.

    • Agricultural-structure front setbacks are 25 feet in F-A, E-A, and U-C, and 20 feet in U-T and A-T.
    • Agricultural-structure rear setbacks are 20 feet in all five listed districts.
    • Agricultural-structure side setbacks are 10 feet in all five listed districts.
    • Non-agricultural-structure front and rear setbacks are 25 feet in all five listed districts.
    • Non-agricultural-structure side setbacks are 25 feet in F-A, E-A, and U-C, and 20 feet in U-T and A-T.
    • The zoning code states that allowed uses and associated structures must comply with the development standards unless a variance is obtained.

    agricultural structure front setback: 25 ft in F-A, E-A, U-C; 20 ft in U-T and A-T · agricultural structure rear setback: 20 ft · agricultural structure side setback: 10 ft · non-agricultural structure front setback: 25 ft · non-agricultural structure rear setback: 25 ft · non-agricultural structure side setback: 25 ft in F-A, E-A, U-C; 20 ft in U-T and A-T

    “Allowed uses and associated structures shall comply with the following development standards, in addition to any other applicable requirements of this Title, unless a variance is obtained in compliance with Section 44-1.80 (Types of Permits).”
  • Building heightDistrict specific (with conditions)

    Maximum structure heights in the county agricultural zoning districts F-A, E-A, U-C, U-T, and A-T in unincorporated Colusa County.

    • Maximum agricultural-structure height is 50 feet in all five listed districts.
    • Maximum accessory agricultural-structure height is 100 feet in F-A, E-A, and U-C, and 50 feet in U-T and A-T.
    • Maximum non-agricultural-structure height is 30 feet in all five listed districts.
    • The zoning code states that allowed uses and associated structures must comply with the development standards unless a variance is obtained.

    maximum agricultural structure height: 50 feet · maximum accessory agricultural structure height: 100 ft in F-A, E-A, U-C; 50 ft in U-T and A-T · maximum non-agricultural structure height: 30 feet

    “Maximum Height for Agricultural Structures 50 ft 50 ft 50 ft 50 ft 50 ft Maximum Accessory Agricultural Structure Height 100 ft 100 ft 100 ft 50 ft 50 ft Maximum Height for Non-Agricultural Structures 30 ft 30 ft 30 ft 30 ft 30 ft”
  • Living in an RVTemporary only (with conditions)

    Recreational-vehicle occupancy during home construction in unincorporated Colusa County.

    • Permanent residence in a recreational vehicle is not allowed.
    • Temporary occupancy requires a Temporary Use Permit and is available only under circumstances specified in the County Code.
    • The cited county page does not state the full conditions in the handout because the linked handout could not be retrieved.
    “You may not live in a recreational vehicle as a permanent residence. [...] you may occupy a Recreational Vehicle temporarily with a Temporary Use Permit.”
  • Tiny homesAllowed (with conditions)

    A state-defined park trailer meeting the county's Tiny Home definition and used as an accessory dwelling unit outside a County- and State-approved Mobile Home or Special Occupancy Park.

    • All utilities must be connected to County-approved systems under an issued County permit.
    • The wheels and tongue must be removed.
    • The structure must be supported by a County-approved foundation system for which a building permit has been issued.
    • The exterior must include typical residential design elements so that the structure resembles a residential structure and not a recreational vehicle, including design elements such as slope roofs, roof material, siding material, and window details, to the satisfaction of the Community Development Director.
    • Skirting must match or complement the exterior and screen the underside chassis and foundation system, to the satisfaction of the Community Development Director.
    • The ordinance states that it becomes effective thirty (30) days after passage; it was passed and adopted on December 14, 2021.

    effective timing: thirty (30) days after passage

    “A Tiny Home ( Park Trailer) located outside ofa County and State approved Mobile Home and/or Special Occupancy Parks is considered an approved type ofaccessory dwelling unit ifthe following criteria are met:”
    One more reviewed finding on this topic
    • Allowed (with conditions) — A tiny home park trailer located outside a county- and state-approved mobile-home or special-occupancy park, when used as an accessory dwelling unit in unincorporated Colusa County.
      “A Tiny Home ( Park Trailer) [...] is considered an approved type ofaccessory dwelling unit ifthe following criteria are met:”
  • Manufactured homesLimited

    Manufactured or mobile-home residential occupancy governed by Colusa County's zoning classifications in unincorporated areas.

    • The zoning table makes manufactured or mobile homes a permitted use in the agricultural-zone table shown, subject to the referenced regulations in Sections 44-2.20(B) and 44-4.70.
    • Temporary mobile-home occupancy is separately identified as a Temporary Use Permit use under Section 44-4.80.
    • Rules vary by zoning classification; the cited zoning code does not establish unrestricted countywide occupancy.
    “Manufactured or Mobile Home P P P P P 44-­‐2.20(B); 44-­‐4.70 Mobile Home (temporary) T T T T T 44-­‐4.80”
    One more reviewed finding on this topic
  • Accessory dwellingsLimited

    State-defined park trailers qualifying as tiny homes located outside County- and State-approved Mobile Home and/or Special Occupancy Parks in Colusa County.

    • All utilities must be connected to County-approved systems under an issued County permit.
    • The wheels and tongue must be removed.
    • The structure must be supported by a County-approved foundation system for which a building permit has been issued.
    • The exterior design must include typical residential design elements so that the structure resembles a residential structure and not a recreational vehicle, including features such as sloped roofs, roof material, siding material, and window details, to the satisfaction of the Community Development Director.
    • Skirting must be installed that matches or complements the exterior and screens the underside chassis and foundation system to the satisfaction of the Community Development Director.
    • Ordinance No. 819 states that it becomes effective thirty days after passage; it was passed and adopted on December 14, 2021, but the source does not state a separate calendar-date effective date.
    “A Tiny Home (Park Trailer) located outside of a County and State approved Mobile Home and/or Special Occupancy Parks is considered an approved type of accessory dwelling unit if the following criteria are met: 1) All utilities are connected to County approved systems under an issued County permit; 2) The wheels and tongue are removed, and the structure is supported by a County approved foundation system for which a building permit has been issued; [...] This ordinance shall become effective thirty (30) days after its passage.”
  • Who permits septicCounty

    Existing and new onsite wastewater treatment systems in unincorporated Colusa County with wastewater design flow of 10,000 gallons per day or less.

    • For systems producing more than 10,000 gpd, systems receiving significant RV holding-tank waste, or systems with above-ground effluent discharge, treatment and dispersal must be approved by the Regional Water Quality Control Board.
    • The chapter does not apply within the jurisdictional limits of a governmental entity that has agreed with the Board of Supervisors to assume responsibility for regulating or issuing OWTS permits.
    • The Environmental Health Division director administers and enforces the chapter on behalf of the County Health Officer.

    maximum wastewater design flow: <= 10000 gpd (Systems exceeding this threshold require Regional Water Quality Control Board approval.) · RV holding-tank waste: significant amounts (Regional Water Quality Control Board approval required.) · above-ground effluent discharge: not covered by ordinary county OWTS administration (Regional Water Quality Control Board approval required.)

    “The director of the Environmental Health Division or his/her assign(s) , on behalf of the County’s Health Officer, shall administer and enforce all provisions of this Chapter relative to installation, maintenance, operation and abandonment of OWTS”
  • Septic permitRequired

    Construction, rebuilding, remodeling, repair, alteration, or replacement of an OWTS serving a residence, business, or other occupied building in unincorporated Colusa County.

    • Plans must be submitted to the Director for approval.
    • For a structure not connected to an approved sanitary sewer, approval of the proposed construction or an OWTS installation permit is required.
    • Permits are valid for one year from issuance and are nontransferable.
    • Applications must be submitted in writing to the Environmental Health Division with fees set by the current Board of Supervisors environmental-health fee resolution.
    • A site evaluation is required before permit approval, subject to the stated testing and waiver provisions.

    permit duration: 1 year (Renewal procedures apply if additional construction time is needed.) · sanitary sewer separation: > 200 feet (The manual states permits are issued only where sanitary sewer is not available within 200 feet.)

    “A permit must be obtained from the Colusa County Environmental Health Department (CCEH) to construct, reconstruct, or repair an onsite wastewater treatment and dispersal system.”
  • Off-grid sanitationLimited

    Off-grid sanitation using OWTS or alternative sanitation systems in unincorporated Colusa County.

    • OWTS may be used where authorized by Chapter 36 and the Onsite Systems Manual, subject to approval, siting, design, installation, inspection, and operating requirements.
    • Surface discharge systems, including surface irrigation, percolation ponds, or evaporation ponds, are not authorized under the County OWTS ordinance.
    • Chemical toilets require a permit except for temporary construction use; the Director may waive the requirement for other temporary activities if no health or safety issue is created.
    • Alternative OWTS require an installation permit and renewable operating permit with monitoring and inspection requirements.
    • Public sewer connection is required within 200 feet when the ordinance conditions are met.

    maximum ordinary county OWTS design flow: <= 10000 gpd (Higher flows require Regional Water Quality Control Board approval.)

    “Wastewater systems that discharge effluent above ground (e.g., via surface irrigation, percolation/evaporation pond) are not covered within the definition of an OWTS and are not authorized under this Chapter.”
  • Well permitRequired

    New wells, modifications to existing onsite supply wells, and well abandonment in Colusa County.

    • Applications are submitted through the County online portal.
    • County Water Wells page states drillers must notify the office 48 hours in advance for inspection.
    • The cited County project document describes these permits as ministerial rather than discretionary.

    advance inspection notice: 48 hours (Applies to drillers.) · domestic/private well fee: 364 USD (County Water Wells fee schedule; other well categories have separate fees.) · well abandonment/destruction fee: 168 USD (County Water Wells fee schedule.)

    “If any modifications are made to the existing onsite supply wells, if either well is to be abandoned, or if any new wells are to be drilled, then a permit would be required from the Colusa County Environmental Health Division within the Community Development Department.”
  • Mandatory utility hookupSewer (with conditions)

    Structures requiring sewage disposal in unincorporated Colusa County located within 200 feet of an approved available sanitary sewer.

    • Connection must be made in the most direct manner possible.
    • A right-of-way and necessary approval from the appropriate sewer authority and Colusa County LAFCO must first be obtained.
    • For existing OWTS, connection is required upon system failure or when major repair, septic-tank replacement, or an OWTS addition is required or proposed, if feasible and approved by the Director.

    distance to available sanitary sewer: <= 200 feet (Connection requirements are subject to feasibility, right-of-way, sewer-authority approval, and LAFCO approval.)

    “Every property where there is proposed a residence, place of business, or other building or place which people occupy, or where persons congregate, reside or are employed, and which proposed structures requiring sewage disposal are within two hundred (200) feet of an approved available sanitary sewer, must be connected to the sanitary sewer in the most direct manner possible, provided a right-of-way and any necessary approval from the appropriate sewer authority and the Colusa County Local Agency Formation Commission (LAFCO) can be first obtained.”
  • Subdividing landRegulated (with conditions)

    Subdivision and parcel-division applications in unincorporated Colusa County.

    • The county identifies its subdivision standards as current, but warns they may change before updates are posted.
    • Tentative parcel maps and tentative subdivision maps are submitted through the county land-use application process.
    • Applicants are directed to contact the Public Works Department to confirm additions, deletions, or changes to the standards.

    Public Works confirmation phone: 530-458-0466

    “The Subdivision Standards accessible on this page are the current standards for Colusa County. The county is in the process of updating the standards, and they may be subject to change prior to being posted.”
  • Driveway accessRequired

    Building permit plot plans for projects subject to Colusa County review in unincorporated areas.

    • The plot plan must show all streets and easements, identify streets, and show the location of the access road.
    • This claim establishes a documentation requirement for the building permit application, not a universal physical driveway-construction standard.
    “7. Show all streets and easements. Identify streets 8. Show the location of the access road”
  • Building in a floodplainLimited

    Development in flood-hazard areas of unincorporated Colusa County that is subject to county review and flood-zone permitting.

    • The County Public Works Department reviews building-permit plot plans for flood hazards and significant grading projects.
    • Colusa County provides resources and forms relating to floodplain permits, including elevation certificates, floodproofing certificates, and FEMA flood-insurance-rate maps.
    • The County fee schedule lists the Flood Zone Development Permit as having no fee.
    • The County's FEMA map page identifies the current FEMA maps as covering the unincorporated areas of Colusa County.
    • The cited county pages do not state a complete prohibition on floodplain development or provide all construction standards, exceptions, or approval criteria.

    Flood Zone Development Permit fee: 0 USD

    “The following resources are forms relating to floodplain permits: Elevation Certificate Form Federal Emergency Management Agency (FEMA) Floodproofing Certificate (PDF) Flood Insurance Rate Maps (FIRMs) for Colusa County”
  • Permit feesPublished

    Published Colusa County Public Works permit fees, including encroachment, transportation, land grading, and flood zone development permits.

    • The encroachment fee is 3% of the estimated cost of work within the County right of way.
    • The permittee is billed for County inspection costs on weekends and holidays.
    • The flood zone development permit has no fee.
    • The fee schedule identifies the cited encroachment fee as adopted under Resolution Number 84-31 and the land grading fee under Ordinance 414.

    encroachment permit fee: 3% of estimated cost of work within County right of way (Permittee billed for County costs for inspections on weekends and holidays.) · flood zone development permit fee: No Fee

    “Encroachment Permit: | 3% of the estimated cost of work within County right of way. Permittee billed for County costs for inspections on weekends and holidays. [Resolution Number 84-31]”
  • Permit processPublished (with conditions)

    County building permit applications handled through Colusa County's online permit portal.

    • All permit applications must be submitted through the Online Permit Portal.
    • Planning reviews setback requirements and whether the proposed use is allowed in the assigned zone.
    • Building reviews project plans and code compliance.
    • Environmental Health reviews well and waste-disposal matters.
    • Depending on location, the fire district reviews State Fire-Safe compliance.
    • Public Works reviews road encroachments, flood hazards, and significant grading.
    • Required materials include electrical and plumbing plans, truss calculations, energy calculations, a plot plan, and when applicable sprinkler and solar plans.
    “ALL Permit Applications must be submitted through the Online Permit Portal.”

California rules that apply here

  • Camping on your landLimited

    Camping in units operated by the California Department of Parks and Recreation statewide.

    • Camping is confined to areas designated for that purpose.
    • Occupancy by the same persons, equipment, or vehicles is generally limited to 30 days in any calendar year in that unit.
    • The Department may establish shorter or longer occupancy limits.
    • When a shorter seasonal limit applies, the camper must vacate the campsite and may not reregister in the unit until 48 hours have expired, measured from 12:00 noon on the checkout day to 12:00 noon on the second day following.
    • A district superintendent may permit one-night camping in a day-use area or portion of one, subject to Department-established fees and vehicle limitations; occupants must vacate by 9:00 a.m. the following morning.
    • California State Parks' current reservation policy states that each campground has a consecutive-night limit, requires a 48-hour absence after that limit, and generally has a 30-night annual maximum, subject to individual park policies.

    general annual occupancy limit: 30 days per calendar year per unit (The Department may establish shorter or longer limits of occupancy.) · return interval after shorter seasonal limit: 48 hours (Measured from 12:00 noon of the checkout day to 12:00 noon of the second day following.) · one-night camping in day-use area: 1 night (Only if permitted by the district superintendent; occupants must vacate by 9:00 a.m. the following morning.)

    “Occupancy by the same persons, equipment, or vehicles of any camping facility is limited to a total of 30 days in any calendar year in that unit.”
    One more reviewed finding on this topic
    • Allowed (with conditions) — Temporary camping in California special occupancy parks, including parks containing recreational vehicles, tents, or camping cabins.
      ““Special occupancy park” means a recreational vehicle park, temporary recreational vehicle park, incidental camping area, or tent camp.”
  • Septic inspectionLimited

    OWTS in a Tier 3 Advanced Protection Management Program with supplemental treatment components, including systems in specified impaired-water-body areas statewide.

    • The requirement applies to OWTS in an Advanced Protection Management Program with supplemental treatment components.
    • Ongoing monitoring must follow the OWTS operation and maintenance manual or occur more frequently if required by the local agency or Regional Water Board.
    • Where telemetry is not possible, the owner or owner's agent must inspect at least monthly while the system is in use and notify the service provider at least quarterly of observed operating parameters.
    • For systems designed to meet disinfection requirements, a service provider must inspect proper operation quarterly while the system is in use unless continuous telemetric monitoring is capable of assessing operation.
    • Quarterly effluent sampling and certified-laboratory requirements apply to systems subject to the disinfection provisions.

    inspection frequency where telemetry is not possible: per monthly (While the system is in use.) · inspection frequency for disinfection systems: per quarterly (While the system is in use, unless continuous telemetric monitoring is capable of assessing operation.)

    “Where telemetry is not possible, the owner or owner’s agent shall inspect the system at least monthly while the system is in use as directed and instructed by a service provider and notify the service provider not less than quarterly of the observed operating parameters of the OWTS. [...] OWTS in an Advanced Protection Management Program designed to meet the disinfection requirements in Section 10.10 shall be inspected for proper operation quarterly while the system is in use by a service provider unless a telemetric monitoring system is capable of continuously assessing the operation of the disinfection system.”
  • Campground & park staysLimited

    Occupancy and use of manufactured homes and mobilehomes in California mobilehome parks and other locations subject to HCD jurisdiction.

    • HCD administers titling and registration for manufactured homes and mobilehomes.
    • HCD-inspected mobilehome parks are subject to health and safety enforcement where local government has not assumed enforcement.
    • Manufactured/mobilehome park regulations address construction, use, maintenance, and occupancy.
    • Separate local land-use, building, fire, health, and utility requirements may apply.
    “MHs may be occupied outside or inside of mobilehome parks and installation and approval for occupancy is governed by the Mobilehome Parks Act (MPA), HSC Sections 18200, et seq., and Title 25, CCR Sections 1000, et seq.”
    One more reviewed finding on this topic
    • Limited — Occupancy and use of recreational vehicles in California special occupancy parks and designated RV sections of mobilehome parks.
      “Unless otherwise allowed by a local ordinance, RVs generally may be occupied only in mobilehome parks or special occupancy parks governed by the Mobilehome Parks Act”
  • county zoning authorityGeneral

    California county legislative bodies' authority to adopt zoning ordinances regulating buildings, structures, land uses, lots, yards, open space, lot coverage, intensity of use, parking, loading, and setbacks within county jurisdiction, including unincorporated areas.

    • The authority is exercised pursuant to Government Code Chapter 4, Zoning Regulations.
    • The statute separately authorizes city legislative bodies; incorporated municipalities may exercise their own zoning authority.
    • Government Code Section 65850 also lists authority to regulate signs and billboards, building and structure location, height, bulk, number of stories, and size, lot and open-space size and use, lot coverage, intensity of land use, offstreet parking and loading, and building setback lines.
    • The cited section states it was amended by Stats. 2017, Ch. 376, Sec. 1, effective January 1, 2018.
    “The legislative body of any county or city may, pursuant to this chapter, adopt ordinances that do any of the following:”
  • county building authorityGeneral

    California counties administering and enforcing state building standards through county building departments, including residential construction in unincorporated areas.

    • Each county must maintain building standards and state building regulations in the office of the building official responsible for administration and enforcement of state building standards.
    • The statewide Title 24 standards apply subject to statutory exceptions and any authorized local amendments or local requirements.
    • The cited HCD bulletin concerns the 2019 California Building Standards Code and its July 1, 2021 supplement; later code editions may supersede those particular edition dates.
    “These codes shall be maintained in the office of the building official responsible for the administration and enforcement of state building standards”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission — ask the county directly.

  • Lot coverage — Maximum lot coverage in unincorporated Colusa County.
  • Agricultural exemption — Potential agricultural exemptions from county zoning, building-permit, or related development requirements in unincorporated Colusa County.
  • Short-term rentals — Short-term or vacation rentals in unincorporated Colusa County.

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Water rights & wells in Colusa County

Whether a new home can legally get its own water here — the sub-state groundwater regime, from California’s water agency.

Actively managed

This basin is under active state management — new water use is scrutinized, though a domestic well is usually still allowed.

Household wellPermit required — restricted

California requires no STATE permit for a domestic well — wells are permitted by the county — but under SGMA a Groundwater Sustainability Agency can meter or restrict new wells in medium/high-priority and critically overdrafted basins, and Executive Order N-7-22 requires counties in those basins to get GSA verification that a new well is consistent with the Groundwater Sustainability Plan before permitting.

Limit: 2 acre-feet/year de minimis under SGMA (Water Code §10721(e)) — largely exempt from GSA metering/fees

California DWR / State Water Board — SGMA de minimis & EO N-7-22 Action 9 FAQ ↗
  • Sacramento Valley high-priority subbasinspartial of county

    High-priority SGMA subbasins (Corning, Colusa, Vina, Antelope-Tehama, South Yuba, North & South American, Solano, Yolo) with adopted GSPs; a new well is subject to GSA/EO N-7-22 consistency review.

    California DWR — SGMA Basin Prioritization ↗

Hybrid state (appropriation + riparian). Groundwater rules change and basin boundaries follow the aquifer, not the county line — confirm current well and appropriation rules with the California state water agency before you buy or drill.Groundwater governance as of Jul 2026, cited to each administering agency.

Living off-grid in Colusa County, California

Is Colusa County a good place to live off-grid or homestead?

Colusa County scores 44/100 on the Bolthole Index, a marginal county profile. Watch-outs: elevated mid-century heat, water, rain, or wildfire exposure and more administrative friction around building and land use.

Do you need a building permit in Colusa County, California?

Colusa County generally requires a residential building permit, and it enforces county zoning. Onsite septic is permitted by Colusa County Environmental Health Division. Owner-builders may act as their own contractor to build their home. These answers are quoted from official sources and independently re-checked. Rules change and cities within the county differ — always confirm with the county before you buy or build.

Can you live in an RV or tiny home on your land in Colusa County?

Living in an RV on your own land in Colusa County is allowed on a temporary basis only: Recreational-vehicle occupancy during home construction in unincorporated Colusa County. Permanent residence in a recreational vehicle is not allowed. Temporary occupancy requires a Temporary Use Permit and is available only under circumstances specified in the County Code. A tiny home is allowed. Confirm with the county before relying on it.

How much does land cost in Colusa County, California?

Land in Colusa County runs about $11,119 per acre, based on the latest county data.

What is the water situation in Colusa County?

Colusa County gets about 24.8" of rain a year, with severe drought in roughly 40.8% of years. On water rights, Colusa County lies in the Sacramento Valley high-priority subbasins — High-priority SGMA subbasins (Corning, Colusa, Vina, Antelope-Tehama, South Yuba, North & South American, Solano, Yolo) with adopted GSPs; a new well is subject to GSA/EO N-7-22 consistency review..

How remote is Colusa County?

A representative private-land location has about 17,055 people within a 30-minute drive and 5,313,539 within two hours. The road-network catchments count population across county lines and clusters of smaller cities; straight-line radius values remain available as a comparison.

How Colusa compares in California

Compare side-by-side →See all 58 California counties ranked →