Off-grid site report

Madison County, MT

45.3588, -111.7431 · 4,948 ft elevation

Read this before you act on anything below. This is my researched starting point for Madison County, MT, not legal advice and not a guarantee. Rules change, and the deciding facts on any specific parcel (setbacks, perc results, overlay districts, deed restrictions, road frontage) live at the county or town office, not in any database. Before you buy land or build, confirm the current rules directly with the local zoning and health offices - the sources on this page tell you exactly who to call.

The local rulesMadison County, MT

Zoning & raw-land occupancy

Varies locallyMadison County has no county-wide zoning ordinance; its Growth Policy is explicitly non-regulatory. However, Montana law allows landowners to petition for small targeted zoning districts, so specific parcels could be zoned. Check with the county Planning Department for your parcel. source

Dwellings, tiny homes & RVs

Unclear - verifyNo county-specific ordinance on tiny homes, THOWs, or RVs was found. Montana's state-level Appendix Q and standard RV classifications likely apply by default, but this is not confirmed for Madison County; ask Planning. source

Building permits & codes

Generally allowedMadison County requires a building permit and follows a state-adopted IRC edition. The county restricts the age of manufactured homes moved in, limits tracts to two dwellings, and won't issue a building permit until septic approval is confirmed. source

Septic & composting toilets

Generally allowedA county permit is required for all septic/wastewater systems, installed only by a Madison County Licensed Installer. Any regularly occupied structure producing wastewater needs a permitted system, with limited exceptions for pre-1991 systems or DEQ-approved public sewage connections. source

Greywater reuse

Unclear - verifyNo Madison County-specific greywater ordinance was found; the county's wastewater regulations address broader treatment systems but not greywater distinctly. Montana's state DEQ rules likely serve as the default, but this is not confirmed at the county level.

Rainwater harvesting

Unclear - verifyNo Madison County ordinance restricting basic rooftop rainwater collection was found, so it's presumed permitted under state default, but this isn't explicitly confirmed for the county.

Private wells & water rights

Generally allowedWell drilling and water rights are governed by the state DNRC, not the county. Madison County does require well water sample testing (nitrates and specific conductance) as part of its septic permit application. source

Living disconnected from utilities

Generally allowedNo Madison County ordinance requires grid electrical connection for a residence. But occupancy still triggers the mandatory wastewater/septic permit requirement regardless of grid status. source

Open the full county page with sources →

Sun30-year normals

Peak-sun hours, annual average: 4.8 hrs/day
Worst month (sizes an off-grid array): 2.5 hrs/day
Yearly output per 1 kW of panels: 1,395 kWh

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Weather1991-2020

Precipitation: 13 in/yr
Snowfall: 45 in/yr
Heating degree days: 8,124 (severe)

How far help isstraight-line

Hospital Madison Valley Medical Center: 0.7 mi
Fire station Station 1: 0.8 mi
Hardware store: none within range
Grocery Madison Foods: 0.6 mi

From OpenStreetMap. Road miles will be longer, often much longer in hill country.

Plan this spot

These open with this location's real numbers already filled in (ZIP 59729).

Size a solar system Heat loss & insulation Firewood per winter Rainwater harvest Garden size Panel tilt

Sources: US Census Bureau geocoder; NLR PVWatts v8 (solar); NOAA NCEI 1991-2020 climate normals (nearest station) or Open-Meteo (ZIP-centroid) for weather; Open-Elevation; OpenStreetMap contributors. Public data retrieved Aug 21, 2026; agencies update their layers on their own schedules. Planning data, not a survey or legal advice.