Zoning, building permits and septic rules in Lewistown, Montana

At a glance

Building permit

Required inside Lewistown city limits; issued by the city building official¹

Zoning

Lewistown has its own zoning code with residential, commercial and floodplain districts²⁴

R-1 minimum lot

7,200 square feet in the R-1 single-family district⁵

R-1 setbacks

Front yard 25 feet, rear yard 20 feet, side yards 5 feet⁶

Septic

Fergus County Environmental Health takes septic applications; city-limit lots need a sewer check³

Inspections

The city building official inspects permitted work inside city limits⁷

Outside city limits

Fergus County has no county-wide zoning; see the county page⁸

Who to call

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Does Lewistown, Montana have zoning, and what does it mean for lot size and setbacks?

Yes. Lewistown regulates land use under its own zoning code, and the rules are set district by district². Districts include R-1, R-1A, R-1B, R-2 and R-3 residential, a residential manufactured home district, neighborhood commercial and a floodplain district⁴. The city's Planning Department says its zoning work covers "the City and the two-miles surrounding the City"⁹, so call before assuming a lot just outside the limit is free of zoning.

In the R-1 single-family district, a lot must be at least 7,200 square feet, except lots of record⁵. R-1 lots need a 25-foot front yard, a 20-foot rear yard and 5-foot side yards, with 10 feet on a side facing a street⁶. Buildings may cover no more than 30 percent of an R-1 lot¹⁰, and a residence in R-1 may stand no taller than 25 feet¹¹. In R-1B the residential height limit is 30 feet¹².

We did not capture the city's rules on minimum house size, accessory dwellings or short-term rentals. Ask the Planning Department about those for your parcel's district.

Do you need a building permit in Lewistown, and who issues it?

Yes. Inside Lewistown city limits, the city building official receives applications and issues the permits the city building code requires¹. The building official also inspects work under each permit⁷. The City of Lewistown Building Department says you bring the necessary documents to its office and receive a building permit once the plans are approved¹³. We did not capture the list of work that needs a permit or the permit fees, so ask the Building Department for the current fee schedule.

Montana's state certified-program list shows Lewistown's building-code authority covers city limits only, and all other areas fall under the State Building Codes Bureau¹⁴. The state's own guidance says a single-family residence in state jurisdiction does not need a state building permit unless a local government requires one¹⁵. Inside Lewistown, the city is that local government.

How do septic permits work for a lot in Lewistown?

Septic applications in Fergus County go through Fergus County Environmental Health, which posts a septic application and site-visit request on its page³. A drainfield permit is still required from the local health department even when a Certificate of Subdivision Approval exists¹⁶.

The county lists a new-system fee of $200.00 with a certified installer and $650.00 for an owner-installed or uncertified-installer system, plus a $275.00 site visit¹⁷. Service fees are added on top¹⁸.

What we could not confirm is whether a lot inside Lewistown city limits must connect to city sewer rather than install a septic system. Ask the Fergus County sanitarian and the city before you buy a lot you plan to septic. Soil matters too: only about 4% of Fergus County soils are rated not limited for a conventional drain field, so expect a site evaluation and possibly an engineered system¹⁹.

Can you live in an RV or tiny home in Lewistown?

We could not confirm it. Lewistown's zoning code includes a use table that mentions travel trailer parks, but we did not establish whether living in an RV or tiny home on a private residential lot is allowed in any city district. Ask the City of Lewistown Planning Department at (406)535-1775 before you park or build anything on a lot inside the city⁹.

The answer is different outside the city. Fergus County has no county-wide zoning ordinance, so no county zoning rule restricts RVs or tiny homes on unincorporated land²⁰. Remember the Planning Department's zoning work also reaches the two miles around the city⁹.

Building a home in Lewistown: the steps, in order

1. Confirm the zoning district of the lot and its setbacks with the City of Lewistown Planning Department⁹.
2. Check whether the lot is in the floodplain district, which has its own chapter of the zoning code⁴.
3. Ask the city and the Fergus County sanitarian whether the lot hooks up to city sewer or needs a septic permit¹⁸.
4. If the lot needs septic, submit the septic application and site-visit request to Fergus County Environmental Health³.
5. Bring plans to the City of Lewistown Building Department and get the building permit¹³.
6. Call for inspections as work proceeds; the building official inspects permitted work⁷.
7. Ask the Building Department what certificate you need at the end; we could not confirm whether the city requires a certificate of occupancy.

What stays with Fergus County, and what to check before you buy?

Septic applications stay with Fergus County Environmental Health, city address or not³. For land outside city limits, use the Fergus County page: the county has no county-wide zoning⁸, and its Planning Office issues development permits that identify property, road and floodplain limits before construction²¹.

Tax and cost context is county-level. Fergus County's effective property tax rate is 0.8% and the median bill is $1,709 a year²²²³. The typical home is valued around $308,789²⁴. Splitting a parcel under 20 acres triggers a state sanitation review²⁵.

Watch-outs

• Lewistown's zoning text we reviewed is the version published through ordinance 1744A in September 2012, so confirm current district rules and the zoning map with the Planning Department before relying on setbacks or lot sizes².
• The city's Planning Department says its zoning work includes the two miles surrounding the city, so a lot just outside the limits may still be subject to city zoning; confirm with the department⁹.
• Whether a Lewistown lot must connect to city sewer, and what inspections or fees apply to wells and septic systems, is unconfirmed; call the Fergus County sanitarian and the city before buying¹⁸.
• Floodplain lots follow a separate floodplain chapter of the city zoning code, and we did not confirm whether development there needs its own permit⁴.

Sources

1. Lewistown MT Code Title 4 Building Regulations, Chapter 1 Building Code (Lewistown), quoted and re-checked
2. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
3. Health Department - Environmental Health, quoted and re-checked
4. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
5. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
6. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
7. Lewistown MT Code Title 4 Building Regulations, Chapter 1 Building Code (Lewistown), quoted and re-checked
8. Central Montana Central Region Hazard Mitigation Plan, Annex F: Fergus County, quoted and re-checked
9. City of Lewistown Planning Department (cityoflewistown.com)
10. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
11. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
12. Lewistown MT Code Title 11 Zoning, Chapter 3 Zoning Districts (Lewistown), quoted and re-checked
13. City of Lewistown Building Department (cityoflewistown.com)
14. Certified City, County and Town Programs, quoted and re-checked
15. bsd.dli.mt.gov, quoted and re-checked
16. Health Department - Environmental Health, quoted and re-checked
17. Health Department - Environmental Health, quoted and re-checked
18. Fergus County Environmental Health (Sanitarian) (fergusmt.gov)
19. 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
20. Montana law on county zoning and building authority
21. Fergus County Planning Office Fee Schedule, quoted and re-checked
22. Effective property tax rate: Bolthole Index county data
23. Median property tax bill: Bolthole Index county data
24. Typical home value (Zillow): Bolthole Index county data
25. deq.mt.gov, quoted and re-checked

Written October 24, 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.