Glendive

Dawson County (Glendive county seat; far-eastern Montana badlands along the Yellowstone River; ~9,000 residents; on the western edge of the Bakken oil boom footprint) does not maintain a comprehensive countywide zoning code. Like most rural eastern-Montana counties, it operates under Montana's permissive default: parcels in unincorporated territory have no county-imposed zoning unless a special zoning district has been formally created under MCA Title 76, Chapter 2, Part 1 (county zoning) or Part 2 (planning-and-zoning districts). Montana SB 528 (2023, codified at MCA § 76-2-345) preempts MUNICIPAL zoning to require ADUs by-right on single-family lots inside city limits — but the preemption does not reach unincorporated county land, where in Dawson County there is generally no zoning to preempt. Glendive (the only incorporated municipality in the county; population ~5,000, just under SB 323's 5,000-resident duplex-preemption threshold) is the only place in the county where SB 528's ADU preemption clearly applies. For unincorporated parcels, the only land-use constraints are typically subdivision review under the Montana Subdivision and Platting Act, on-site sewage rules under MCA Title 75 Ch. 5, and any voluntary covenants on the parcel. An ADU on an unincorporated Dawson County parcel is generally permissible without county zoning approval, subject to building-code (state-adopted IRC) compliance and septic permitting through the local sanitarian.

State-floor overlay: Montana SB 528 (MCA § 76-2-345) establishes a state floor for ADU permissibility in incorporated cities; the county's lack of a zoning code in most of its unincorporated territory means ADUs face no county zoning bar there.

Dawson County administers FEMA NFIP floodplain regulation along the Yellowstone River corridor — the dominant overlay in the county. The Yellowstone is one of the longest free-flowing rivers in the lower 48, and its floodplain is broad through Glendive and the Bloomfield / Lindsay reach. Wildland-urban interface (WUI) designations are minimal in this prairie / badlands landscape; no Glacier-style forest interface here, but isolated grassland fire risk is real. The Makoshika State Park badlands south of Glendive are a localized scenic / recreational overlay but do not impose ADU restrictions on private parcels. No coastal or seismic overlays apply.

• FEMA NFIP Special Flood Hazard Areas - Yellowstone River corridor — A new ADU in a mapped SFHA must be elevated to or above the Base Flood Elevation; elevation cost can add $15,000-$40,000 to a Glendive-area ADU project. Lowest floor must be at or above BFE for residential structures.
• Grassland and prairie fire risk areas — No WUI permit required, but voluntary defensible-space practices recommended for properties bordering CRP / native-grass tracts.
• Glendive Commercial Historic District (NRHP) — ADU work on a NRHP-listed contributing property triggers Section 106 review only if federal financing or permitting (e.g., FHA, USDA Rural Development, HUD-184) is involved.

Dawson County does not operate a county building department in the traditional sense — Montana law does not require small rural counties to administer the building code, and Dawson County has not opted in. For unincorporated parcels, building permits are generally not required by the county for residential construction outside any formally-created zoning district. The state-adopted Montana Building Code (based on IBC/IRC, currently 2018 edition with 2024 amendments adopted by the Montana Department of Labor and Industry) applies as a technical floor, but enforcement in counties without a building department falls back to the State Building Codes Bureau on complaint or to inspection at point-of-sale via lender or insurer requirements. On-site wastewater (septic) is the single permit most likely to be required: the local sanitarian (typically through the Eastern Montana Public Health District or the County Sanitarian) issues septic permits under MCA Title 75 Ch. 5 and ARM Title 17 Ch. 36. Subdivision review by the County Planning Office applies if the ADU project requires creating a new parcel; placing an ADU on an existing parcel does not normally trigger subdivision review.