Building permits, zoning and land rules in Fallon County, Montana

An ordinary home in unincorporated Fallon County does not need a county building permit¹. Fallon County, Baker and Plevna use Montana's state-administered code program rather than a certified local program². A Montana building permit is required before construction of a non-residential building or a residential building with five or more dwelling units⁸. Residential buildings with four or fewer dwelling units instead require state electrical and plumbing permits, while the small-residential building-permit exemption does not cover transient-guest lodging². Farm and ranch buildings may be exempt from the state building permit, but sanitation, trade, fire, floodplain, airport and subdivision requirements can still apply². With no county building permit for an ordinary home, an owner may build their own home, though state licensing for electrical, plumbing and HVAC work may still apply².

The Montana Building Codes Program handles applicable state building permits for Fallon County, Baker and Plevna because none operates a certified local code program². When a state permit applies, the permit holder calls the building inspector at least 24 hours before an inspection, and the inspector has 72 hours to respond¹². Fallon County Planning is the local contact for floodplain permits, subdivision review and zoning questions¹. A complete floodplain application can require plans, fees, notices and other permits, with a decision due within 60 days and at least 15 days for public comment¹³. Septic systems go through the Fallon County Sanitarian for every address in the county, city or not^6,7. A county-road approach is reviewed by the Road Department and approved by the county commissioners^14,15.

Unincorporated Fallon County has no general countywide zoning ordinance³. We could not confirm a countywide minimum home size or residential lot size; ask Fallon County Planning about the parcel and any subdivision-specific standard¹. Workforce-housing rules apply to that use, the Baker airport affected area has its own controls, and Plevna zoning applies only inside the town's corporate limits^5,9,16. Subdivision review remains required where the county's subdivision regulations apply⁴. In covered subdivisions, the total setback is 300 feet from a river, 200 feet from a perennial stream, and 130 feet from an intermittent stream, lake, pond or reservoir unless applicable zoning supplies the standard¹⁷. Floodplain permits are separate, and Fallon County Planning publishes a $750 application fee¹.

Residential septic systems are approved by the local health department before installation, and Fallon County names its County Sanitarian as the contact^6,7. Systems must meet Montana standards, and local rules may be stricter¹⁸. A Certificate of Subdivision Approval is Montana DEQ's sanitation approval for a subdivision; a lot created after 1961 and smaller than 20 acres will generally have a certificate or sanitary restrictions¹⁰. A proposed subdivision within 500 feet of a qualifying public water or wastewater system must connect unless the department grants a waiver; cost is considered practical at no more than three times an approvable onsite system¹⁹. New cesspools and new pit-privy systems are prohibited, while new holding tanks generally require a specified waiver¹⁹. Only 34.2% of county soils lack severe limits for a conventional drain field, so verify the site before assuming a standard system will work²⁰. We could not confirm routine septic inspection requirements; ask the Sanitarian.

Fallon County has no zoning in unincorporated areas, so county zoning does not restrict tiny homes or RV use there³. Subdivision, floodplain, building-trade and septic rules still apply, so ask the County Sanitarian how wastewater would be handled before moving onto a parcel^4,7. Plevna regulates RV occupancy through approved RV parks: those projects require zoning and subdivision review, utility connections, permits and inspections⁵. Plevna also limits an RV parked on a public or private street to 24 hours and requires RV-park spaces to sit at least 15 feet from adjacent structures⁵. A Fallon County short-term rental is a state-regulated public accommodation whose plans are reviewed by the County Sanitarian; the cited rule does not establish a separate county land-use approval²¹.

1. Confirm whether the parcel is in unincorporated Fallon County, Baker, Plevna or the Baker airport affected area because the applicable land-use rules differ¹⁶.
2. Ask Fallon County Planning about subdivision, floodplain, workforce-housing, airport-area and waterbody-setback controls before fixing the building site^1,4,17.
3. Contact the County Sanitarian for septic approval, check the subdivision file for sanitary restrictions, and ask whether proximity to public utilities requires connection^7,10,19.
4. Determine whether Montana requires a building permit and obtain the state electrical and plumbing permits required for a small residential project^2,8.
5. File the required water-right paperwork before using a new well¹¹.
6. If access meets a county road, submit the approach application for county review^14,15.

Start with water: Fallon County averages about 15.5 inches of precipitation a year, so confirm a dependable supply rather than assuming rainfall will cover household and livestock needs²⁰. Every new Montana water use needs a water right; groundwater use above 35 gallons per minute or 10 acre-feet per year needs a permit, while smaller uses may qualify for the exception process¹¹. Check the subdivision record for sanitation restrictions and test the proposed drainfield area because only 34.2% of county soils lack severe limits for a conventional system^10,20. Map flood hazards, waterbody setbacks and the road approach before settling on a homesite^13,14,17. Typical property tax is about 0.6%, with a median annual bill near $1,359²⁰.