If you plan to put in a culvert, armor an eroding bank, pull gravel, build a crossing, or move dirt anywhere in the bed or immediate banks of a year-round creek, Montana law requires you to get permission first. The permit costs nothing in Park County. Doing the work without it can cost $500 a day.
It's called a 310 permit, from the Natural Streambed and Land Preservation Act of 1975. It is administered not by a state agency but by your local Conservation District — a body most new landowners have never heard of.
The statute covers any "physical alteration or modification that results in a change in the state of a natural, perennial-flowing stream or river, its bed, or its immediate banks." In practice that means:
Perennial means year-round flow — and importantly, a stream that goes dry because it's being irrigated out still counts as perennial. Springs are covered too. Intermittent and ephemeral channels are not covered by the 310, though they may still trigger federal review. Historic maintenance of existing irrigation facilities and livestock grazing are expressly excluded.
There's no fixed setback in the statute. Jurisdiction is the bed and immediate banks, and the Conservation District is the only body that decides where that line falls. When in doubt, ask them — that call is free.
After you apply, the district notifies Montana Fish, Wildlife & Parks, and an inspection team — a district supervisor, an FWP biologist, and you — walks the site. Each member files a written recommendation, and the board affirms, modifies, or overrules. You then have 15 days to sign and return the decision form; if you don't, the permit is void. Unless the board says otherwise, wait 15 days before starting work.
Practically, a complete application filed by the 15th gets resolved in four to eight weeks. Miss the deadline and you wait a month.
You can act immediately. The law exempts "actions that are necessary to safeguard life or property, including growing crops, during periods of emergency" — but you must file written notice with the district within 15 days, stating the location, what you did, when, and what the emergency was. Miss that 15-day window and you face the same penalties as unpermitted work. The board reviews it afterward and can require modification or removal.
Doing the work without consent makes you guilty of a misdemeanor punishable by a fine up to $500, or subject to a civil penalty up to $500 for each day the violation continues — each day is a separate violation. On top of any fine you must restore the stream as near as possible to its prior condition, or pay for the restoration. Both the landowner and the contractor can be named.
This is the part that catches people. The same culvert can implicate five agencies:
The Yellowstone is legally navigable from Emigrant downstream, which means the streambed there belongs to the state and work below the low water mark needs a DNRC land use license on top of your 310.
The Corps also maintains a Special River Management Zone on the upper Yellowstone — a 48-mile reach running from above Emigrant to below the Shields River and Mission Creek confluences — where any regulated activity requires advance notification to the Corps. If your project is on the main stem in Park County, assume the Corps is involved.
Work in a channel has to happen when flows are low. The Park Conservation District won't approve May construction, and post-2022-flood guidance from the local watershed group is blunt about it: get the work done well before spring runoff, or wait until flows drop. Between the monthly application cycle and the seasonal window, a bank project you think about in April is realistically a late-summer project.
Primary sources: MCA 75-7-101 through 75-7-125 (Natural Streambed and Land Preservation Act of 1975), particularly 75-7-103 (definitions), 75-7-112 (procedure and 60-day decision), 75-7-113 (emergencies), 75-7-123 (penalties); Montana DNRC stream permitting program and 2025 Conservation District Law Book; Park Conservation District 310 permit pages; Gallatin Conservation District; USACE Upper Yellowstone Special Area Management Plan (2011) and Special River Management Zone regional conditions; Upper Yellowstone Watershed Group post-flood recovery guidance. Confirm current procedure with the Park Conservation District before relying on this.
Tell us about your project and we'll point you toward people who do it in your county — or tell you honestly if we don't know anyone good there yet. Start here.