Mammoth Lakes — Nonconforming Uses

Last reviewed: July 2, 2026

Overview

This page explains how the Town of Mammoth Lakes treats nonconforming uses, structures, and parcels under Title 17 (Zoning). It summarizes the legal definitions, what may be continued, when nonconforming rights are lost, and the limits on repairs, additions, and rebuilding. For rules about site development (setbacks, lot standards), see the town’s Mammoth Lakes Development Standards and for project-level review see Mammoth Lakes Design Review. Key nonconforming rules are in CHAPTER 17.96 — Nonconforming Uses, Structures, and Parcels of Title 17 (Zoning) (see § 17.96.010–§ 17.96.100) .

What “nonconforming” means in Mammoth Lakes (legal basics)

• A nonconforming use is a use that was lawful when established but no longer allowed in the current zone (Nonconforming use definition; see § 17.96.030) .
• A nonconforming structure is a building lawfully built but not meeting current setbacks, height, separation, or other development standards (Nonconforming structure definition; see § 17.96.030) .
• A nonconforming parcel (lot) is a legally created lot that no longer meets present area/width/depth/access requirements (Nonconforming parcel definition; see § 17.96.030 and § 17.96.070) .

Practical takeaway: if your use, building, or lot predates a zoning change, Title 17 recognizes it as legal nonconforming and provides specific rules for continuation, alteration, and loss of status (Chapter 17.96) .

Core rules from CHAPTER 17.96 (what you can and cannot do)

• Continuation: A legal nonconforming use, structure, or parcel may be continued, transferred, or sold (but not enlarged) (§ 17.96.030(d)) .
• Maintenance and repairs are allowed for nonconforming uses/structures (routine maintenance is permitted) (§ 17.96.030(e)) .
• Additions/alterations:
  • Residential nonconforming structures: additions allowed provided the addition complies with applicable codes/standards (§ 17.96.040(b)(1)) .
  • Commercial nonconforming structures: additions limited to no more than 25% of existing floor area (excl. garages), and no more than once every three years; improvements must meet the California Building Standards Code (§ 17.96.040(b)(1)) .
  • No alteration may increase the discrepancy with current standards (setbacks/heights/coverage) (§ 17.96.040(b)(2)) .
• Destruction / restoration:
  • If destroyed to 50% or less of replacement value, restoration (and resumption of the nonconforming use) is allowed if started within one year and diligently pursued (§ 17.96.050(a)) .
  • If destroyed beyond 50% (or voluntarily razed), the replacement must conform fully to current zoning and the nonconforming use may not be resumed (§ 17.96.050(a)) .
• Loss of status:
  • Continuous discontinuance of the nonconforming use for one year or more terminates nonconforming rights; Director may extend the one-year period administratively for up to an additional one year in exceptional cases (§ 17.96.060(a)(1)–(3)) .
• Nonconforming signs have special rules (amortization, prohibited changes, 50% ruin threshold, historic exceptions) — see § 17.48.120 and related sign rules (§ 17.48.120 et seq.) .
• Nonconforming multifamily structures destroyed >50% may be rebuilt subject to Government Code § 65852.25 and local discretion (§ 17.96.050(c)) .

Quick code anchors: § 17.96.010 – Purpose, § 17.96.030 – Continuation and maintenance, § 17.96.040 – Additions & alterations, § 17.96.050 – Restoration, § 17.96.060 – Loss of status, § 17.96.070 – Nonconforming parcels .

District-by-district breakdown (where nonconforming rules interact with zoning)

The Town Zoning Map identifies district symbols and names (Table—Zoning Districts) — examples include A (Airport), D (Downtown), OMR (Old Mammoth Road), MLR (Mixed Lodging/Residential), RSF (Residential Single-Family), RMF-1, RMF-2, RR (Rural Residential), P‑QP (Public & Quasi‑Public), OS (Open Space), and plan-specific districts such as NVSP and CSP (Table 17.16.030 — Zoning Districts) .

Below are district subsections tied to the actual Mammoth Lakes district symbols. For each, I identify the statutory locus where the district is defined or the development standards are found; then summarize what the nonconforming chapter means in that district. For full permitted-use and dimension tables, consult the cited chapter(s).

RSF (Residential Single‑Family)

• Purpose & where listed: § 17.20.010 describes RSF as single-family residential (no transient rentals, hotels/motels, or B&Bs) and refers to Table 17.20.020 for allowed uses; development standards are in Table 17.20.030 (§ 17.20.010–§ 17.20.030) .
• Typical permitted uses: detached single-family dwellings, accessory dwelling units (ADUs) (subject to Chapter 17.52 and state ADU law) (§ 17.20.020, Table 17.20.020) .
• Key dimensional standards (quick): lot area 7,500 sf, front yard 20 ft, side yard 10 ft, max coverage 40%, max height 35 ft (see Table 17.20.030) (§ 17.20.030) .
• Nonconforming treatment: Residential nonconforming structures may be added to (additions allowed if they meet applicable codes) and may be repaired (Chapter 17.96), but additions must not increase the inconsistency with current RSF standards (§ 17.96.040(b)(1–2)) .

RMF‑1 and RMF‑2 (Residential Multiple‑Family zones)

• Purpose & uses: RMF‑1 allows mixed residential uses; RMF‑2 is focused on multiple‑family developments; Table 17.20.020 lists multifamily and accessory uses and permit types (§ 17.20.010–§ 17.20.020) .
• Standards: Table 17.20.030 sets lot areas, setbacks, coverage and density caps (e.g., RMF‑1 density ~12 units/acre) (§ 17.20.030) .
• Nonconforming treatment: Nonconforming multifamily structures destroyed >50% may be rebuilt subject to Government Code § 65852.25 and local conditions (§ 17.96.050(c)) — verify multifamily rebuild rights with the Director and applicable state law .

RR (Rural Residential)

• Purpose: larger lots, lower density; transient rentals generally not permitted; see § 17.20.010(b)(1) and Table 17.20.020 for uses and permit rules .
• Standards: Table 17.20.030 shows lot area 15,000 sf, front yard 25 ft, max coverage 30% etc. (§ 17.20.030) .
• Nonconforming treatment: same Chapter 17.96 rules apply; note that many RSF/RR limits on transient use are initiative-protected — rezoning or amending transient use limits has additional voter‑approval rules (see § 17.20.010(d–e)) — verify with the Director for any change that might affect a nonconforming transient use .

D (Downtown), OMR (Old Mammoth Road), MLR (Mixed Lodging/Residential) — Commercial / mixed-use districts

• Where to read: see CHAPTER 17.24 — Commercial Districts and Table 17.24.030‑1 and the use tables in Chapter 17.52 (use/permit matrices) (§ 17.24.030, § 17.52.100) .
• Typical uses: retail, restaurants, lodging, multifamily residential (subject to limits), live/work, etc.; active frontage rules and ground‑floor use limits are specified in the use tables (§ 17.52.100) .
• Dimensional standards: commercial lot/placement tables, FAR limits (e.g., FAR up to 2.0 in some commercial districts) and building placement rules are in Table 17.24.030‑1 and related tables (§ 17.24.030) .
• Nonconforming treatment: a nonconforming commercial use/structure may be repaired; commercial additions are limited to 25% unless the enlargement eliminates the nonconformity; nonconforming signs have separate amortization rules (§ 17.96.040, § 17.48.120) .

P‑QP (Public & Quasi‑Public), OS (Open Space), A (Airport), NVSP/CSP (Specific Plans)

• Each of these districts appears in Table 17.16.030 and has tailored allowed uses and standards in the code or the associated specific plan; nonconforming rules of Chapter 17.96 apply but particular public utilities and infrastructure have exception language (e.g., modernization of public services allowed while not increasing area/use) (§ 17.96.020(c)) .

If you need parcel‑level dimensional numbers or the full permitted‑use lists for any specific symbol above, consult the district chapter (Chapters 17.20–17.32 for residential, 17.24 for commercial) and Table 17.16.030 (Zoning Districts) — those are the controlling places in Title 17 where permitted uses and numeric standards are specified and cross‑referenced to Chapter 17.96 for nonconforming treatment .

Quick reference table — most decision‑relevant nonconforming rules

Checklist — what an applicant must satisfy (nonconforming work)

• Establish that the use/structure/parcel is a lawful pre‑existing condition (e.g., recorded deed, prior permits, business records). See § 17.96.030 and § 17.96.070 .
• Confirm whether proposed work is routine maintenance, an allowed addition, or a prohibited enlargement under § 17.96.040; prepare plans accordingly (commercial additions limited to 25%) .
• If restoring after damage, document replacement value and timing to evaluate the 50% test and the one‑year restoration window (§ 17.96.050) .
• If claiming a nonconforming parcel is a legal building site, produce deed/subdivision/variance/lot‑line‑adjustment evidence per § 17.96.070 .
• Check District standards (Chapters 17.16–17.32) for setbacks, coverage, height, and parking rules that may affect allowed work; confirm no increase in nonconformity (§ 17.96.040(b)(2)) .
• Prepare to satisfy any required design review or administrative/use permits, or to apply for a variance if you need relief from current district standards (§ 17.92.040 for Director authority; see Chapters on permit procedures) .
• Ensure all construction complies with the California Building Standards Code where improvements are made (expressly required in § 17.96.040(b)(1)) .

Risks & Ambiguities

Plain‑English summary

If your building, use, or lot in Mammoth Lakes was legal before a zoning change made it illegal, Title 17 lets you keep it — you can repair it and, in many residential cases, add to it — but you cannot expand the nonconforming part in a way that makes it more nonconforming; destruction above 50% generally forces full compliance with current rules, and stopping the use for a continuous year typically ends nonconforming rights (verify facts with the Director) (§ 17.96.030–§ 17.96.060) .

Source References

• Title 17 — ZONING, Town of Mammoth Lakes: CHAPTER 17.96, Nonconforming Uses, Structures, and Parcels (§ 17.96.010 – § 17.96.100) — controlling nonconforming rules.
• CHAPTER 17.16 — Zoning Map and Table 17.16.030 (Zoning Districts) — lists district symbols (Table 17.16.030) (§ 17.16.030)
• CHAPTER 17.20 — Residential Zoning Districts: purposes, allowed uses, development standards (Table 17.20.020, Table 17.20.030) (§ 17.20.010 – § 17.20.030) (residential district rules referred to above).
• CHAPTER 17.24 — Commercial District Development Standards (Table 17.24.030‑1 etc.) and CHAPTER 17.52 (Use tables) for commercial/mixed‑use allowed uses and permit rules.
• CHAPTER 17.48 — Signs (nonconforming sign rules and amortization rules) (§ 17.48.120).
• CHAPTER 17.36 — Standards for all development (setbacks, height measurement, snow storage) — referenced by district tables (§ 17.36.010 – § 17.36.110)
• For ADU interactions with nonconforming conditions: Town ADU rules (17.52.055) and state ADU law (see internal ADU resources) — Town ADU provisions summarized in CHAPTER 17.52 and ADU guidance in the uploaded state ADU handbook (for context).

Retrieved passages

• Mammoth Lakes Zoning Code (§ 17.96.020) High relevance show source text
• Mammoth Lakes Zoning Code (Section 17.48.090) High relevance show source text
• Mammoth Lakes Zoning Code (chapter pertaining) High relevance show source text
• Mammoth Lakes Zoning Code (§ 50079.5.) High relevance show source text
• Mammoth Lakes Zoning Code (§ 17.100.030) High relevance show source text
• Mammoth Lakes Zoning Code (§ 50093.) High relevance show source text
• Mammoth Lakes Zoning Code (ARTICLE V.) High relevance show source text
• CBC § 66314 (§ 66314) High relevance show source text
• Mammoth Lakes Zoning Code (§ 17.100.060) High relevance show source text
• Mammoth Lakes Zoning Code (§ 17.100.040) High relevance show source text
• Mammoth Lakes Zoning Code (§ 65852.25.) High relevance show source text
• Mammoth Lakes Zoning Code (§ 17.100.040) High relevance show source text
• CFC § 66427.4 (§ 66427.4.) Medium relevance show source text
• Mammoth Lakes Zoning Code (§ 66314) Medium relevance show source text
• Mammoth Lakes Zoning Code (§ 66333) Medium relevance show source text
• CBC § 66321 (§ 66321) Medium relevance show source text
• CBC § 17.36.110 (Section 17.36.110) Medium relevance show source text
• Mammoth Lakes Zoning Code Medium relevance show source text
• Mammoth Lakes Zoning Code (Title 17) Medium relevance show source text
• Mammoth Lakes Zoning Code (Section 17.48.130.) Medium relevance show source text
• Mammoth Lakes Zoning Code (chapter shall) Medium relevance show source text
• California Residential Code Medium relevance show source text
• California Residential Code Medium relevance show source text
• Mammoth Lakes Zoning Code (Chapter 17.48) Medium relevance show source text
• Mammoth Lakes Zoning Code (§ 4) Medium relevance show source text
• CRC § 000 Medium relevance show source text

Cited sections

• Title 17 — ZONING, Town of Mammoth Lakes: CHAPTER 17.96, Nonconforming Uses, Structures, and Parcels (**§ 17.96.010 – § 17.96.100**) — controlling nonconforming rules. (Title 17)
• CHAPTER 17.16 — Zoning Map and Table 17.16.030 (Zoning Districts) — lists district symbols (**Table 17.16.030**) (**§ 17.16.030**) (CHAPTER 17.16)
• CHAPTER 17.20 — Residential Zoning Districts: purposes, allowed uses, development standards (Table **17.20.020**, Table **17.20.030**) (**§ 17.20.010 – § 17.20.030**) (residential district rules referred to above). (CHAPTER 17.20)
• CHAPTER 17.24 — Commercial District Development Standards (Table **17.24.030‑1** etc.) and CHAPTER 17.52 (Use tables) for commercial/mixed‑use allowed uses and permit rules. (CHAPTER 17.24)
• CHAPTER 17.48 — Signs (nonconforming sign rules and amortization rules) (**§ 17.48.120**). (CHAPTER 17.48)
• CHAPTER 17.36 — Standards for all development (setbacks, height measurement, snow storage) — referenced by district tables (**§ 17.36.010 – § 17.36.110**) (CHAPTER 17.36)
• For ADU interactions with nonconforming conditions: Town ADU rules (17.52.055) and state ADU law (see internal ADU resources) — Town ADU provisions summarized in CHAPTER 17.52 and ADU guidance in the uploaded state ADU handbook (for context). (CHAPTER 17.52)
• MammothLakes_ZoningCode.md
• 2025 California ADU handbook.md

• Official Mammoth Lakes code library