Off-Grid Living in Lake County, Montana

I'll be upfront: Lake County, Montana is one of the more fragmented places I've researched for off-grid purposes, because it has no single countywide zoning code. Instead, the Lake County Planning Department administers thirteen separate zoning districts (mostly clustered around lakeshores), and the City/County Zoning District around Polson is jointly run by the City of Polson and the county. If your parcel isn't in one of those mapped districts, you're likely unzoned at the county level, though floodplain and Growth Policy provisions can still reach you. Bottom line: before you assume anything about what you can build or do, find out which district (if any) your parcel sits in.

Zoning and dwellings. Because rules are set district-by-district, permitted uses vary. I found that the Upper West Shore district explicitly allows single-family homes including manufactured homes, and that small structures under 100 square feet (away from Flathead Lake's high water line) may be exempt from permits in some districts. I did not find a countywide rule on tiny homes on wheels or long-term RV living, so I'd treat Montana's state baseline as the default and confirm specifics with Lake County Planning.

Building permits. Montana's Department of Labor & Industry runs the state Building Codes Program, and state rule requires any certified local jurisdiction to enforce the same code as the state. Separately, Lake County requires its own Zoning Conformance or Building Notification Permit before construction, issued through Lake County Planning. I couldn't confirm whether Lake County is "certified" to run its own inspections or defers to the state office, so ask Planning directly.

Septic and wastewater. This is where Lake County is strict and specific. Per Lake County's Wastewater Treatment System Regulations, no excavation or construction on anything requiring wastewater facilities can begin without an Installation Permit from the county's Environmental Health Department, and system designs must come from a Montana-licensed Professional Engineer or Registered Sanitarian. Holding tanks are allowed only as a last resort, under a 2016 County Board of Health resolution, when site constraints (like no piped water) rule out other options. Composting toilets aren't addressed separately in what I found, so don't assume they let you skip the wastewater permit process.

Greywater and rainwater. No standalone county ordinance surfaced for either; greywater appears to fall under the same wastewater permitting rules, and rainwater collection likely just follows Montana's general allowance for personal, non-potable use. Confirm specifics with Environmental Health.

Wells and water rights. Here's the twist: much of Lake County lies within the Flathead Indian Reservation, where the Flathead Reservation Water Management Board, not the state DNRC, is the exclusive authority over water rights and new well approvals. Off-reservation land still falls under DNRC. Lake County Environmental Health says plainly it doesn't handle water rights, so you'll need to first figure out which jurisdiction your land is in.

Utilities. No standalone rule forces a grid or municipal hookup, but you can't avoid the permitting system entirely, since any habitable structure needing wastewater service still triggers Environmental Health's permit requirement.