Local zoning · Modoc County

Modoc County — Nonconforming Uses

Nonconforming Uses under the Modoc County local zoning and planning code, with the controlling citations.

Last reviewed: July 6, 2026

Overview

This page explains how nonconforming uses, structures, and lots are handled in unincorporated areas of Modoc County under the county’s zoning ordinance (Title 18). Use it alongside the county-wide zoning overview, your base-zone rules in Zoning, and the county’s Development Standards when evaluating a site. Nonconformities often turn on details like lawful establishment dates, abandonment, overlay districts, and damage thresholds, which are all addressed below with direct code citations.

Plain-English rule of thumb: if a use or structure was lawful before today’s zoning applied, it may continue subject to strict limits on expansion, damage, abandonment, and overlays such as airport hazards. See the definitions and rules in § 18.154.020, § 18.154.030, and § 18.06.700.

What the Modoc County code says about nonconforming uses, structures, and lots

Definitions and scope. The code defines a nonconforming use and a nonconforming structure and applies the chapter’s regulations to all legally established nonconformities in unincorporated areas. The code also clarifies that work ordered by a public authority for health/safety is allowed even on nonconformities (§ 18.154.020).
• A glossary definition also appears in § 18.06.700.
Continuation and routine maintenance. Lawfully established nonconforming uses and structures may be continued; routine maintenance and repairs are allowed (§ 18.154.030).
Expansion/intensity limits. Increasing the “intensity” of a nonconforming use is allowed only if the building is not altered or enlarged. Moving, altering, enlarging, or reconstructing a nonconforming structure is prohibited unless it is brought into full conformity or a use permit is obtained, subject to a narrow lot-line exception (§ 18.154.040).
Lot line adjustments for nonconforming parcels. The Planning Commission may approve a lot line adjustment that reduces or even increases a parcel’s existing nonconformity if certain findings are made (e.g., to improve health/safety or the design of the affected parcels), processed under Gov. Code § 66412(d) (§ 18.154.050).
Destruction threshold. If a nonconforming structure is damaged or destroyed beyond 75% of its market value (as determined by the County Assessor for that fiscal year), it can be repaired/rebuilt only if brought into full compliance—or with a use permit (§ 18.154.060).
Abandonment. If a nonconforming use is abandoned, discontinued for any reason, or changed to another use for a continuous period of one year, it cannot be re-established (§ 18.154.070).
Nuisances and enforcement. The Board of Supervisors may require modification or termination of a nonconformity declared a nuisance (§ 18.154.080), and every violation of Title 18 is explicitly a nuisance subject to enforcement (§ 18.158.010).
Substandard lots. A legally created lot that is smaller/narrower than the current standard and not merged under the Subdivision Map Act may be developed if criteria in § 18.110.020 are met (nonconforming lots). Coordinate these findings with Design Review or site plan processes as applicable.
Overlay districts—Airport Hazard (AH). Separate “airport hazard” rules allow continuation of nonconformities but require a Planning Commission permit before replacing, substantially altering, repairing, rebuilding, or allowing a nonconforming tree to grow higher; approvals cannot increase air navigation hazards (§ 18.90.130–.140). These permits process similarly to a variance under Chapter 18.132. See Overlay Districts.
Special amortization (storage screening). Where a legal nonconforming open storage situation conflicts with county-wide screening requirements, the owner has six months from notice to amortize and bring storage into compliance (§ 18.44.070.B; also mirrored in RR/RL maintenance provisions).

One-table snapshot: Key nonconforming rules

Topic	What the code requires in unincorporated areas	Code Reference
Continuation	Lawful nonconforming uses/structures may continue; routine maintenance allowed	§ 18.154.030
Expansion/alteration	May not move/alter/enlarge a nonconforming structure unless brought into conformity or a use permit is obtained	§ 18.154.040.B
Increase in “intensity”	Only if the structure is not altered or enlarged	§ 18.154.040.A
Damage/destruction	If damage exceeds 75% of market value, full compliance or a use permit is required to rebuild	§ 18.154.060
Abandonment	1 year of discontinuance = loss of nonconforming use rights	§ 18.154.070
Nonconforming lots	Development may proceed on certain legally created substandard sites if § 18.110.020 criteria are met	§ 18.110.020
Airport Hazard overlay	Continuation allowed, but Commission permit needed to replace/alter; cannot worsen hazards	§ 18.90.130–.140; Ch. 18.132
Open storage amortization	6 months to add required screening and conform	§ 18.44.070.B (and parallel provisions)

How base zoning interacts with nonconformities (district-by-district)

Modoc County establishes principal zones and overlays in § 18.02.030. Nonconforming status is assessed against the specific standards and purposes of the zone that applies to your parcel—check your base zone in Zoning and any overlays in Overlay Districts.

Below are the principal zones most often implicated when evaluating whether an old use or structure conforms. For each, we list purpose, common permitted uses, key dimensional standards (so you can spot where a structure is “nonconforming”), and a note on how nonconformities typically arise in practice.

AE — Agricultural Exclusive

Purpose: Protect agriculture; allow supporting resource-based uses (§ 18.18.010).
Typical permitted uses: Crop/livestock operations, accessory agricultural buildings, limited residential (1 dwelling under 75 acres; 2 dwellings over 75 acres), roadside stands (§ 18.18.030.L).
Key standards: Dwellings 20 ft front/side-street; 50 ft side/rear; lot coverage 10% (≤5-acre parcels exempt from 10% cap) (§ 18.18.060).
Nonconforming watch-outs: Older farmsteads with small setbacks or accessory buildings near boundaries; second dwellings added before current criteria.

AG — Agricultural General

Purpose: Grazing/dryland farming and other non-intensive agriculture (§ 18.24.010).
Typical permitted/permit uses: Agriculture; with approvals, a broad range including farm employee housing, energy facilities, and even motels/RV parks in specific cases (§ 18.24.040–.050).
Key standards: Minimum lot size often 3 acres; larger near AE-adjacent lands (§ 18.24.060.A). Setbacks typically 20 ft front/side-street; 10 ft rear/side (§ 18.24.060.B).
Nonconforming watch-outs: Historic homes or sheds closer than current setbacks; parcels under today’s minimum sizes.

RC — Resource Conservation

Purpose: Conservation lands with limited residential; relies on AG use lists (§ 18.16.030–.060).
Typical permitted uses: One single-family dwelling; select AG-related uses; public utilities; conservation activities.
Key standards: Minimum parcel size 80 acres; 20 ft front/side-street; 30 ft side/rear (§ 18.16.060).
Nonconforming watch-outs: Legacy lots much smaller than 80 acres; dwellings added before today’s standards.

RR — Rural Residential

Purpose: Rural character residential, typically 1–15 acres (§ 18.30.010).
Typical permitted uses: Single-family home and accessory uses; limited low-intensity recreation (§ 18.30.030).
Key standards: Front/side-street 20 ft; side/rear 30 ft; lot width 120–150 ft depending on RR subzone (§ 18.30.060).
Nonconforming watch-outs: Older homes with smaller yards; preexisting small lots; RV use limitations separate from zoning conformance.

RL — Residential Low Density

Purpose: Lower-density urban/rural-edge neighborhoods (§ 18.32.010).
Typical permitted uses: One single-family dwelling; certain public/quasi-public uses (§ 18.32.030).
Key standards: Front/side-street 20 ft (dwellings); 5 ft side/rear; 10,000–15,000 sf lots when on public utilities; more if not (§ 18.32.060).
Nonconforming watch-outs: Legacy lots under 10,000 sf; eaves/garages intruding into today’s yards.

RH — Residential High Density

Purpose: Accommodate higher-density housing; protect neighborhoods from hazards and nuisances (§ 18.36.010).
Typical permitted uses: Single-family or duplex (when minimum lot met), with broader residential spectrum under permits (§ 18.36.030).
Key standards: Dimensional rules cross-referenced to Ch. 18.110 and RH chapter; check Development Standards. Not found in retrieved materials for full numeric setbacks.
Nonconforming watch-outs: Multi-plexes built under older ratios/parking.

RT — Rural Town

Purpose: Mixed residential, small-scale commercial, and agriculture in small unincorporated communities (§ 18.40.010).
Typical permitted uses: One- or two-family dwellings, bed-and-breakfasts, retail in buildings, restaurants, offices/services, small care facilities (§ 18.40.030).
Key standards: See Ch. 18.110 for cross-cutting rules; parcel-specific “main street” patterns often implicate yard nonconformities.
Nonconforming watch-outs: Older storefronts at zero setback; mixed-use established before current rules.

C — Commercial

Purpose: General commercial areas; retail, services, lodging. Title 18 lists standards in Chapter 18.44 (uses/development standards).
Typical permitted with use permit: Broad commercial mix including dwellings by permit; outdoor sales/storage; bars; service stations (§ 18.44.050).
Key standards: 6,000 sf minimum lot; 60 ft width; 5 ft yards (10 ft when abutting RH/RL/RR or RT with a dwelling) (§ 18.44.060).
Nonconforming watch-outs: Legacy lots under 6,000 sf; buildings on property lines; non-screened storage must be screened within 6 months of notice (§ 18.44.070.B).

IL — Industrial Light

Purpose: Light industrial near or adjacent to residential; indoor-oriented operations (§ 18.50.010).
Typical permitted/permit uses: Light assembly/packaging; with permit, caretaker units, multifamily at limited density, truck yards, airports (§ 18.50.030–.040).
Key standards: 6,000 sf lot; 10 ft front/side-street; 5 ft sides/rear, but 20 ft+ if abutting RH/RL/RR/RT; max 75 ft height (lower when abutting residential) (§ 18.50.050).
Nonconforming watch-outs: Older yards or heights exceeding today’s residential-adjacency step-backs.

I — Industrial

Purpose: Heavier industry; protect scarce industrial land (§ 18.54.010).
Typical permitted/permit uses: Manufacturing/assembly, storage/wholesale; with permit, heavy processing and high-impact uses (§ 18.54.030–.040).
Key standards: 3-acre lot; 10 ft front/side-street; side/rear can be 0 ft, but 50 ft if abutting RH/RL/RR/RT; max 100 ft height with adjacency limits (§ 18.54.050).
Nonconforming watch-outs: Older plants with yard/height intrusions along residential edges.

PD — Planned Development; PF — Public Facilities; U — Unclassified

PD: Custom entitlements; conformance is measured against PD approvals (see revocation/extension procedures in § 18.126.100–.110).
PF: Public facility siting; confirm with Land Use. Not found in retrieved materials for numeric standards.
U: “Holding zone” until precise zoning; permitted uses tied to general plan, with 3-acre baseline lot size in § 18.66.060 (§ 18.66.010–.060).

How overlays can change nonconforming outcomes

AH — Airport Hazard overlay: Allows continuation but tightly controls changes; a Planning Commission permit is required before replacement, substantial alteration/repair, or replanting of nonconforming features, and approvals cannot worsen airport hazards (§ 18.90.130–.140). Processed like a variance (Ch. 18.132).
FH — Flood Hazard overlay: The floodplain chapter sets strong construction/elevation standards and a variance process (§ 18.71.170; § 18.71.250), which may indirectly affect how and whether a damaged nonconforming structure can be rebuilt. Coordinate with Variances and Exceptions.
EP/M, AR, SP: Overlay rules can supersede or modify principal zone standards (§ 18.150.050.E, also § 18.74.010–.030).

Practical guidance when dealing with a nonconformity

Document lawful establishment and the effective date of current zoning for your parcel (see § 18.02.060 on county applicability).
Check yard, height, lot size, and use tables in your base zone; many nonconformities arise from setbacks or lot minimums (e.g., RL yards of 20 ft front/side-street, 5 ft side/rear; I zone 50 ft buffers when abutting residential) (§ 18.32.060; § 18.54.050).
Before altering any nonconforming structure, confirm if full conformance is required or if a use permit is an option (§ 18.154.040).
For nonconforming lots, review § 18.110.020 and, if needed, lot line adjustment criteria in § 18.154.050.
In AH areas, obtain the required Commission permit before replacing or significantly altering nonconforming trees/structures (§ 18.90.140).
Open storage must meet screening within 6 months when noticed—even if legal nonconforming (§ 18.44.070.B). Coordinate fencing with Landscaping and Screening.
Parking, signs, and site features are governed by Ch. 18.110 and sign chapters; if you modify a site, check Parking and Signage. Many districts expressly defer to Ch. 18.110.
Separate from zoning, construction must meet the California Building Standards Code. This page does not cover building code compliance.

Checklist

Confirm parcel is in the unincorporated county and identify base zone + overlays on the zoning maps (§ 18.02.040–.050).
Establish evidence the use/structure was lawful when created (§ 18.154.020–.030).
Determine whether the nonconformity is a use, a structure, and/or a lot-size issue (§ 18.06.700; § 18.110.020).
Check if the use has been discontinued for ≥1 year (§ 18.154.070).
If damaged, obtain the Assessor’s market value and apply the 75% threshold (§ 18.154.060).
If altering or enlarging, assess whether full conformance is required or whether a use permit path exists (§ 18.154.040). Coordinate Design Review as needed.
In Airport Hazard areas, secure the Planning Commission permit before replacing/altering a nonconforming feature (§ 18.90.140).
For nonconforming lots, evaluate a lot line adjustment and required findings (§ 18.154.050).
If open storage is involved, schedule screening within the 6-month amortization window after notice (§ 18.44.070.B).

Risks & Ambiguities

Issue	Why it matters	What to verify
75% destruction test	Crossing the threshold forces full compliance or a use permit to rebuild	Assessor’s valuation year, scope of “market value,” and timing (§ 18.154.060)
“Intensity” vs. “enlargement”	You may increase activity but not alter/enlarge the building	Whether proposed work changes the building envelope (§ 18.154.040.A–B)
One-year abandonment	Using a site intermittently can risk losing rights	Evidence of continuous use and any gap periods (§ 18.154.070)
Airport Hazard overlay	Separate permit needed; cannot worsen air hazards	Whether parcel is in AH overlay and permit conditions (§ 18.90.130–.140)
Nonconforming lots	Development may proceed on substandard but legal lots	Merger status; § 18.110.020 criteria; septic/water capacity (§ 18.110.020)
Storage amortization	Legal nonconforming storage must be screened within 6 months	Date of violation notice; fence design per Ch. 18.44.070.B (and related sections)
Enforcement as nuisance	Violations are declared a nuisance	Current compliance status; enforcement history (§ 18.158.010)

Plain-English Summary

If your property in unincorporated Modoc County has an older, once-lawful use or building that no longer fits today’s zoning, you can typically keep using it—but you face limits on enlarging, rebuilding after major damage, and resuming after a long pause. Overlays like airport hazard zones can add special permits. Before changing anything, line up your paperwork, check setbacks and buffers in your base zone, confirm overlay rules, and use the county’s permit tools—including Variances and Exceptions where appropriate—to avoid accidentally losing nonconforming rights.

Source References

Modoc County Zoning Code Title 18: Chapter 18.154 (Nonconforming Uses and Structures) — § 18.154.020–.080.
Definitions — § 18.06.700 (Nonconforming structure or use).
General applicability and zoning maps — § 18.02.040–.070; list of principal/overlay zones — § 18.02.030.
General development standards and substandard lots — § 18.110.020.
Airport Hazard overlay — § 18.90.120–.140 (plus Ch. 18.132 for variance procedure).
Open storage amortization/screening — § 18.44.070.B (and parallel “Conservation of values” sections in RR/RL).
Enforcement — Ch. 18.158.
Zone standards/examples cited: AE (§ 18.18.010; § 18.18.060); AG (§ 18.24.060); RC (§ 18.16.060); RR (§ 18.30.060); RL (§ 18.32.060); RT (§ 18.40.010, § 18.40.030); C (§ 18.44.050–.060); IL (§ 18.50.010; § 18.50.050); I (§ 18.54.050).

Information Gaps

Complete numeric setback table for the RH zone: Not found in retrieved materials.
Full text of § 18.110.020 (Substandard building sites) beyond the introductory clause: Not found in retrieved materials.
Chapter heading for 18.44 to confirm the zone name in the retrieved excerpt: Not found in retrieved materials.
Parcel-specific or case-by-case interpretations: Verify with the jurisdiction.

Sources

Retrieved passages

Modoc County Zoning Code (§ 1) High relevance
Modoc County Zoning Code (title and) High relevance
Modoc County Zoning Code (Section 66412) High relevance
Modoc County Zoning Code (Section 18.100.060.) High relevance
Modoc County Zoning Code (Chapter 18.132.) Medium relevance
Modoc County Zoning Code (title became) Medium relevance
Modoc County Zoning Code (chapter shall) Medium relevance
Modoc County Zoning Code (Chapter 8) Medium relevance
Modoc County Zoning Code (Section 11362.7) Medium relevance
Modoc County Zoning Code (title when) Medium relevance
Modoc County Zoning Code (section 18.100.030.) Medium relevance
Modoc County Zoning Code (Chapter 18.110) Medium relevance
Modoc County Zoning Code (Chapter 18.74) Medium relevance
Modoc County Zoning Code (Section 18.100.050) Medium relevance
Modoc County Zoning Code (Section 18.100.030) Medium relevance
Modoc County Zoning Code (Chapter 18.32) Medium relevance
CPC § 65662 (section may) Medium relevance
Modoc County Zoning Code (section 18.100.010) Medium relevance
Modoc County Zoning Code (Section 18.100.020) Medium relevance
Modoc County Zoning Code (chapter shall) Medium relevance
Modoc County Zoning Code (chapter shall) Medium relevance
Modoc County Zoning Code (§ 5401) Medium relevance
Modoc County Zoning Code Medium relevance
Modoc County Zoning Code (Chapter 18.50) Medium relevance
Modoc County Zoning Code (Chapter 18.110) Medium relevance

Cited sections

Official Modoc County code library

Frequently asked questions

Can I expand a nonconforming building in unincorporated Modoc County?

Generally no—moving, altering, enlarging, or reconstructing a nonconforming structure is prohibited unless you bring it into full conformity or obtain a use permit. Routine maintenance and repairs are allowed (§ 18.154.040–.030).

What happens if my nonconforming building is heavily damaged by fire or a storm?

If damage exceeds 75% of the structure’s market value for that fiscal year (as determined by the County Assessor), you cannot rebuild unless the new work conforms to current zoning—or you obtain a use permit (§ 18.154.060).

How long can a nonconforming use sit idle before I lose the right to resume it?

A continuous period of one year of abandonment, discontinuation for any reason, or change to another use ends the right to reestablish the nonconforming use (§ 18.154.070). Keep records of continuous operation.

Can I adjust lot lines to fix a nonconforming parcel?

Yes. The Planning Commission may approve a lot line adjustment that reduces—or even increases—an existing parcel nonconformity when specific findings are made (health/safety or improved parcel design) and no new nonconforming lots are created (§ 18.154.050).

Are there special rules if my property is near an airport?

Yes. In the Airport Hazard overlay, nonconforming trees/structures may remain, but replacing, substantially altering, repairing, or allowing a nonconforming tree to grow higher requires a Planning Commission permit, and approvals cannot increase hazards to air navigation (§ 18.90.130–.140).

I have longstanding open storage that doesn’t meet today’s screening rules—do I have to fix it?

Yes. Even if storage was legal, the County can require screening; property owners typically have six months from notice to install sight-obscuring fencing and bring storage into compliance (§ 18.44.070.B).

Can I develop a legally created lot that’s smaller than today’s minimum?

Possibly. A substandard (but legally created and not merged) lot can be developed if it meets the criteria of § 18.110.020 and all other applicable standards. Verify utilities, access, and any overlay constraints.

Do ADUs have to correct nonconforming conditions first?

State law limits denials based on certain nonconforming zoning conditions for ADUs. See California ADU law for state standards; verify local applicability alongside Modoc’s ADU provisions and § 18.154.040 for structural changes. Not found in retrieved materials for a countywide ADU–nonconforming cross-reference.

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