Bolthole Index

Mono County, California

Building permits, zoning and land rules in the Town of Mammoth Lakes, California

The Town of Mammoth Lakes, California requires a Town building permit for new construction, additions, remodels and most other building work.1 The Town has its own zoning districts, separate from Mono County's.2 Septic and onsite wastewater matters, even inside town limits, go through Mono County Environmental Health, not the Town.3

At a glance

Building permit
Required from the Town for new construction, additions, remodels, plumbing, electrical and more1
Building code
2025 California Building Code adopted by the Town4
Zoning
Town of Mammoth Lakes has its own zoning districts2
Septic
Mono County Environmental Health handles onsite wastewater3
Accessory dwelling
Allowed on lots that already have a primary dwelling; needs a Town building permit5
Tiny home
Only as an ADU, and only if it meets the California Building Standards Code6
Manufactured home
Allowed where single-family dwellings are permitted, on an approved permanent foundation7

Who to call

Building permits

Town of Mammoth Lakes Building Division

Town building permits, plan review and inspections inside Mammoth Lakes; routes projects to outside agencies such as the fire district, water district and Mono County Health Department

(760) 965-3632

[email protected]

437 Old Mammoth Road Suite 230, Mammoth Lakes, CA 93546

Septic permits

Mono County Environmental Health - Onsite Wastewater Treatment Systems (OWTS) Program

OWTS permits, greywater systems and septic-system review

760-924-1830

1290 Tavern Road, Mammoth Lakes, CA 93546

Contact details are copied from each office’s official page and were checked against it on October 10, 2026.

Off-grid gear

Going off-grid in Town of Mammoth Lakes means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in the Town of Mammoth Lakes, California?

Yes. The Town requires a building permit for new construction, additions, alterations, repairs, remodels, plumbing, electrical work, demolition, solar and battery installs, reroofs, siding and decking replacement, and woodstove or fireplace installs.1 The Town points applicants to California Building Code section 105.2 for work that is exempt from a permit.1

The Town has adopted the 2025 edition of the California Building Code as its building code, along with the state plumbing, electrical, mechanical, residential, energy and wildland-urban interface codes.4 These rules apply inside the Town only; Mono County's Building Division states that it does not oversee or permit work within the Town.8

Who issues building permits in Mammoth Lakes, and how do you reach them?

The Town's Building Division issues building permits inside town limits. Applicants send an electronic submittal with all required documents to [email protected], and questions about a specific project go to the Building Division at (760) 965-3632.89

The Building Division may route a project to Engineering or Planning, and depending on scope you must also get approvals from outside agencies such as the fire protection district, the community water district and the Mono County Health Department.9 The Town publishes a Building Division fee schedule; its current listing is for fiscal year 2026-27, effective August 16, 2026, and fees vary by project.10

Does Mammoth Lakes have zoning, and what does it mean for ADUs, tiny homes and manufactured homes?

Yes. The Town of Mammoth Lakes defines its own zoning districts, including Airport, Downtown, Industrial, Residential Multi-Family and Resort districts, and these are separate from Mono County's zoning for unincorporated land.2 Look up your parcel's district with the Town before you plan a project.

Accessory dwelling units are allowed only on lots that already have a primary dwelling, need a Town building permit, and may not be rented for 30 consecutive days or less.5 An ADU must have at least 150 square feet or the minimum efficiency-unit area under state law.5 A tiny home or RV-type unit can serve as an ADU only if it is modified to meet the California Building Standards Code.6

Manufactured homes are allowed as dwellings where single-family homes are permitted, on an approved permanent foundation and with roof eaves and overhangs of at least one foot.7

How do septic permits work in Mammoth Lakes?

Septic permits do not come from the Town. Mono County Environmental Health runs the onsite wastewater treatment systems program that covers septic matters in Mammoth Lakes.3 The county office is at 1290 Tavern Road and can be reached at 760-924-1830.11

Mono County prohibits seepage pits and cesspools and requires permits to be issued before construction begins.11 A permit application needs a fee, a plot plan and a site location map, and a site evaluation with percolation tests is required when applicable.12 Mono County's soils are a real constraint: only 5.1% of its soils rate as not very limited for a conventional drain field, so expect a site evaluation and possibly an engineered system.13

If you are inside town limits, confirm with Environmental Health and the Town whether sewer service or an onsite system applies to your lot.

Can you live in an RV or camp on land in Mammoth Lakes?

We could not confirm a rule for living in an RV on a private lot inside town limits. The Town code we found limits overnight camping in Town parks and recreation areas without a permit, and prohibits overnight parking of trailers, campers or motorhomes on park property without a Town permit.14 That rule covers park property, not your own lot.

The Town's RV rule for private land is unconfirmed, so ask the Town's Building Division at (760) 965-3632 before you place an RV or tiny home.8 Mono County has its own temporary RV rules for unincorporated land, and they do not apply inside the Town.15

Building a home in Mammoth Lakes: the steps, in order

  1. Confirm with the Town which zoning district your parcel is in and what it allows.2
  2. Contact Mono County Environmental Health at 760-924-1830 about septic or sewer for the lot, and before any private well.11
  3. Submit your building permit application and all required documents electronically to the Town Building Division.9
  4. Collect the outside-agency approvals the Building Division tells you are needed, which can include the fire protection district and community water district.9
  5. If the lot is in a special flood-hazard area, build to the Town's flood standards, which cover anchoring, elevation or floodproofing and protected utilities.16
  6. Pay the fees listed on the Town's current fee schedule.10

What stays with Mono County, and what to check before you buy in Mammoth Lakes?

Septic permits stay with Mono County Environmental Health.3 Mono County also runs building permits, zoning and its own rules for unincorporated land around the Town, so confirm a parcel is inside Town limits before you rely on either set of rules.8

Before buying, weigh the county-level context too. About 90.3% of Mono County is federal land, the effective property tax rate is 0.8%, and the nearest city of 100,000 or more is about 94 miles away.171819 The county's precipitation averages 15.2 inches a year, and short-term rentals, setbacks and height limits for the Town were not confirmed, so check them with the Town.20

Watch-outs

  • Searches for Mono County rules (building, zoning, RV) will not apply inside the Town of Mammoth Lakes, because the county states it does not permit work within the Town.8
  • We could not confirm setbacks, height limits, lot coverage, minimum home size or short-term rental rules for Town lots; ask the Building Division at (760) 965-3632.8
  • Only a small share of Mono County soils suits a conventional septic field, so septic feasibility should be settled before you buy.13

Sources

  1. Building Permits (Town of Mammoth Lakes), quoted and re-checked
  2. All Layers and Tables (OpenData/Planning), quoted and re-checked
  3. Environmental Health (Town of Mammoth Lakes), quoted and re-checked
  4. Mammoth Lakes Municipal Code § 15.04.030, Codes adopted (Town of Mammoth Lakes), quoted and re-checked
  5. § 17.52.055, Accessory dwelling units (Town of Mammoth Lakes), quoted and re-checked
  6. § 17.52.055, Accessory dwelling units (Town of Mammoth Lakes), quoted and re-checked
  7. § 17.52.190, Mobilehomes and manufactured homes (Town of Mammoth Lakes), quoted and re-checked
  8. Town of Mammoth Lakes Building Division (townofmammothlakes.ca.gov)
  9. Building Permits (Town of Mammoth Lakes), quoted and re-checked
  10. Payment and Fees (Town of Mammoth Lakes), quoted and re-checked
  11. Mono County Environmental Health - Onsite Wastewater Treatment Systems (OWTS) Program (monocounty.ca.gov)
  12. Onsite Wastewater Treatment Systems (OWTS), quoted and re-checked
  13. 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
  14. § 12.32.270, Overnight camping (Town of Mammoth Lakes), quoted and re-checked
  15. Mono County General Plan — Land Use Element (2025), quoted and re-checked
  16. § 12.20.080, Provisions for flood hazard reduction (Town of Mammoth Lakes), quoted and re-checked
  17. Federal land share: Bolthole Index county data
  18. Effective property tax rate: Bolthole Index county data
  19. Straight-line distance from the county center to the nearest city of 100,000+ people: Bolthole Index county data
  20. Annual precipitation: Bolthole Index county data

Written October 10, 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.

Answers from the rulebook for Town of Mammoth Lakes

Town of Mammoth Lakes’s own rules

  • Building permitRequired

    New construction and listed building-related work inside Mammoth Lakes town.

    • The Town page identifies work exempt from a permit by reference to California Building Code § 105.2.
    “A Building Permit is required for new construction, additions, alterations, repairs, remodels, plumbing, electrical work, demolition, spa installs, solar panel and battery storage installs, reroofs, siding replacement, decking replacement, woodstove/fireplace installs, and others.”
  • Building code adoptedAdopted

    Building construction inside Mammoth Lakes town.

    • The Town also adopts the California Plumbing, Electrical, Mechanical, Administrative, Historical, Wildland Urban Interface, Existing Building, Energy, Residential, Green Building Standards, and Reference Standards Codes listed in § 15.04.030.
    “The 2025 edition of the California Building Code, together with Appendix P ("Sleeping Lofts"), Chapter 1 and the adopted referenced standards thereto, as developed by the International Code Council, is adopted by reference as the building code of the Town.”
  • Camping on your landLimited

    Overnight camping in Town parks and recreation areas.

    • Overnight camping requires a permit except for the listed youth-group and permitted trailer, camper, and motorhome exceptions.
    • Overnight parking of trailers, campers, or motorhomes is prohibited on park property without a Town permit.
    “Overnight camping without a permit is prohibited with the following exceptions:”
  • Tiny homesLimited

    A tiny home used as an accessory dwelling unit inside Mammoth Lakes town.

    • A mobile home, recreational vehicle, or other movable habitable space, including a tiny home, that does not comply with the California Building Standards Code cannot be used as an ADU unless modified to meet those standards.
    • The ADU must otherwise comply with § 17.52.055.
    “A mobile home, recreational vehicle, or other movable habitable space (e.g., park model home, tiny home, etc.) that does not comply with the California Building Standards Code shall not be used as an ADU, unless it is modified to meet the aforementioned standards.”
  • Manufactured homesAllowed (with conditions)

    A mobilehome or manufactured home used as a dwelling outside a mobilehome park inside Mammoth Lakes town.

    • Single-family dwellings must be permitted in the applicable zoning district.
    • The home must comply with applicable zoning standards, be installed on an approved permanent foundation, comply with the California Building Standards Code and Town building-code requirements, and have roof eaves and overhangs of at least one foot.
    “A mobilehome or manufactured home shall be allowed as a dwelling outside of a mobilehome park and where single-family dwellings are permitted consistent with Government Code § 65852.3, subject to the following standards:”
  • Accessory dwellingsAllowed (with conditions)

    Accessory dwelling units on qualifying parcels inside Mammoth Lakes town.

    • The lot or parcel must contain a primary dwelling unit.
    • Each ADU requires a Town building permit and must comply with applicable California Building Standards Code and Mammoth Lakes Fire Protection District requirements.
    • Short-term rental of an ADU for 30 consecutive days or less is prohibited.
    • An ADU must have at least 150 square feet or the minimum efficiency-dwelling-unit area required by Health and Safety Code § 17958.1.

    minimum gross floor area: >= 150 square feet (or the minimum required for an efficiency dwelling unit as defined in Health and Safety Code § 17958.1)

    “ADUs are permitted as an accessory use only on lots or parcels containing a primary dwelling unit.”
  • Driveway accessLimited

    An additional ADU parking area and driveway access inside Mammoth Lakes town.

    • The additional parking area must be accessed by the same driveway as the primary dwelling unless a second driveway is approved under Public Works Town Standards.
    “The additional parking area shall be accessed by the same driveway as the primary dwelling unless a second driveway is approved pursuant to the "Residential Driveway Standards" for a second driveway specified in the Public Works Town Standards;”
  • Building in a floodplainRequired

    New construction and substantial improvements in special flood-hazard areas inside Mammoth Lakes town.

    • Requirements include anchoring, flood-resistant materials, protected utilities, elevation or floodproofing, and certified elevation verification.
    • On-site waste disposal systems must be located to avoid impairment or contamination during flooding.
    “In all areas of special flood hazards the following standards are required:”
  • Permit feesPublished (with conditions)

    Town building permits inside Mammoth Lakes town.

    • The Town lists multiple fiscal-year fee schedules and identifies FY 2026-27 as effective August 16, 2026; fees vary by applicable schedule and project.
    “Building Division Fee Schedule FY26-27 - effective 8-16-26”
  • Permit processPublished (with conditions)

    Town building-permit applications inside Mammoth Lakes town.

    • The Building Division may route projects to Engineering or Planning.
    • Depending on scope, applicants must procure approvals from outside agencies working with the Town.
    • Required documents must accompany the electronic submittal.
    “Send an electronic submittal including all required documents to [email protected].”

Rules another office applies inside Town of Mammoth Lakes

Town of Mammoth Lakes does not set these itself; the county, a health district or the state does, and they apply to every address inside its limits.

  • Who permits septicCounty

    Onsite wastewater and septic matters inside Mammoth Lakes town are handled through Mono County Environmental Health.

    • The County page identifies an Environmental Health office in Mammoth Lakes and lists Onsite Wastewater Treatment Systems as a program.
    “Onsite Wastewater Treatment Systems (OWTS)”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask Town of Mammoth Lakes or Mono County directly.

  • Owner-builder exemption — Owner-builder construction inside Mammoth Lakes town.
  • Certificate of occupancy — Residential construction and occupancy inside Mammoth Lakes town.
  • Minimum dwelling size — Primary single-family dwellings inside Mammoth Lakes town.
  • Setbacks — Primary residential structures inside Mammoth Lakes town.
  • Lot coverage — Primary residential structures inside Mammoth Lakes town.
6 more unanswered
  • Building height
  • Off-grid sanitation
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Short-term rentals

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.

Unanswered questions are usually a sign that Town of Mammoth Lakes publishes no rule on the point, not that none exists. Mono County’s page lists the county offices to call.

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