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

A single-family residence in Treasure County generally does not need a Montana state building permit unless it is inside a local jurisdiction that requires one by ordinance or resolution¹. Montana requires a state building permit before covered construction begins, while state-jurisdiction exemptions include farm and ranch buildings, owner-use garages and storage buildings, and residential buildings with fewer than five dwelling units unless they serve transient guests¹. Montana has adopted a uniform state building code for residential and commercial construction, but those exemptions still apply; certified local programs may enforce the code, and the state program has jurisdiction elsewhere⁸. Covered projects also receive state inspections; the state publishes inspectors assigned to Treasure County⁹. Montana contractor-licensing law allows an owner to work on the owner's own property, but that exemption does not erase applicable permits and is limited when the owner builds for prompt resale⁴.

Treasure County's Floodplain Administrator works out of the courthouse in Hysham, at 307 Rapelje Ave, Hysham, MT 59038, phone (406) 342-5547¹⁰. That office handles the development permit required for new work inside a mapped Special Flood Hazard Area⁶. Building permits and inspections for covered projects in state jurisdiction go through Montana's Building Codes Program, which publishes inspectors assigned to Treasure County^1,9. Septic follows a separate state-and-local track: Montana DEQ issues applicable subdivision sanitation approval, but the Treasure County health department issues the required drainfield permit even when a lot already has that approval³. To reach the County Sanitarian / Environmental Health office, start with the Treasure County courthouse at (406) 342-5547¹⁰.

Unincorporated Treasure County has no countywide zoning ordinance; the county Growth Policy is non-regulatory and discusses zoning as a possible future action². Because there is no countywide zoning ordinance, unincorporated Treasure County sets no zoning-based minimum dwelling size, minimum lot size, general setback, lot-coverage limit, or building-height limit, and zoning does not restrict accessory dwellings, tiny homes, or manufactured homes². Septic, floodplain, building-code, subdivision, deed, and access requirements can still affect a parcel. The Town of Hysham is a separate jurisdiction, so the countywide answer does not establish the town's rules². Ask Hysham directly about land in town, and review private covenants and the parcel's legal history before treating a lack of county zoning as a clean slate.

Septic approval in Treasure County can involve two authorities. Montana DEQ reviews sanitation facilities for qualifying subdivisions and issues a Certificate of Subdivision Approval³. The Treasure County health department still requires and issues a drainfield permit even when DEQ has already issued that certificate³. Soils make early testing worthwhile: only 12.9% of the county's land is free of severe limitations for a conventional drain field¹¹. Montana generally requires a Beneficial Water Use Permit for groundwater use over 35 gallons per minute or 10 acre-feet a year; qualifying smaller wells still need the state's required filing before use⁵. Treasure County's general residential septic-inspection procedure and any countywide public-utility connection mandate could not be confirmed; ask the County Sanitarian before finalizing a site plan.

Unincorporated Treasure County's lack of countywide zoning means county zoning does not restrict tiny-home or manufactured-home occupancy, but sanitation, floodplain, building-code, subdivision, access, and private-covenant requirements can still apply². Treasure County's rules for long-term RV living on private land could not be confirmed, so ask the county courthouse and County Sanitarian before using an RV as a residence. Montana's camping rules for state trust land do not answer what is allowed on private acreage. On state trust land, a trailer or RV must remain within 50 feet of a customary access point, and temporary stays are limited by the land's lease status or campground designation¹². Contact Hysham separately for property in town because Hysham is outside the countywide zoning answer².

1. Ask whether the parcel is under state building-code jurisdiction or a separate local jurisdiction, then confirm whether the project is exempt; a single-family residence generally does not need a state permit unless a local jurisdiction requires one¹.
2. For covered work, submit plans and the state Building Permit/Plan Review Application before construction¹.
3. If the parcel is part of a qualifying land division, confirm Montana DEQ sanitation approval, then obtain the Treasure County health department's drainfield permit before septic installation³.
4. Address water rights before using groundwater; uses over 35 gallons per minute or 10 acre-feet per year require a permit, while a qualifying smaller well requires the state's filing⁵.
5. Ask the Floodplain Administrator whether the site is in a designated Special Flood Hazard Area and obtain a development permit when required⁶.
6. For a new or changed approach onto a state highway, obtain an MDT approach permit or right-of-way agreement; projects with greater highway impacts can receive additional state review^13,14.

Water and soils are the headline concern: annual precipitation is 15.1 inches, severe drought occurs in 12.5% of years, and only 12.9% of the county's soils are free of severe septic limitations¹¹. Before buying, verify a usable water source and get the proposed drainfield area evaluated. Unincorporated Treasure County has no countywide zoning, but Hysham is separate, and parcel-specific subdivision and floodplain requirements can still apply^2,6. For a recently divided tract, confirm Montana DEQ sanitation approval when applicable and verify that any agricultural exemption actually restricts the divided land to agricultural use^3,15. Confirm legal access too: a new or modified connection to a state highway requires an MDT approach permit or right-of-way agreement¹³.