What Does Montana's Stream Access Law Mean When You Buy River or Creek Frontage?
Owning both banks doesn't mean you own the water. Here's what the public can and can't do on the stream that runs through your land, and how to check before you buy.
Short answer: Montana's Stream Access Law lets the public use any natural, flowing stream for recreation up to the ordinary high-water mark, even where it crosses private land. Buying river or creek frontage gives you the bank, the setting, and often the streambed, but it does not give you the right to keep anglers and floaters off the water. The public still cannot cross your land to get there. Knowing exactly what the law grants, and where your rights as the owner hold firm, is the difference between a frontage purchase you understand and one that surprises you a year in.
Most buyers who call us about river or creek frontage have the same picture in their head: a stretch of water that becomes theirs, private, the way a fenced pasture is private. Then we explain how Montana actually works, and there's a pause on the line.
This post is for the buyer seriously looking at frontage on the Yellowstone, the Boulder, a spring creek, or any of the smaller waters that thread through Park County and southwest Montana. By the end you'll know what the actually grants the public, what it doesn't, what the recent fights over access mean for owners, and the specific questions to ask before you sign. This is the single most misunderstood part of buying water frontage in this state, and it's the kind of thing better understood before closing than after.
What is Montana's stream access law, in plain terms?
Montana's Stream Access Law gives the public the right to use the state's natural, flowing rivers and streams for recreation up to the ordinary high-water mark on both sides, regardless of who owns the adjoining land. It was passed by the Montana Legislature in 1985, codified at , and it remains some of the strongest public-water access law in the country.
The law grew out of two Montana Supreme Court decisions in 1984 that held the state's surface waters belong to the public for recreational use. The Legislature wrote those rulings into statute the next year. Four decades later, the core principle has held through repeated court challenges: if water flows naturally and is capable of recreational use, the public can be on it, even when it runs through a private ranch.
For a frontage buyer, that's the headline. The water itself is not something you buy and fence. You're buying the land along it, the access from your own property, the views, the privacy of the banks above the high-water line, and in many cases the streambed underneath. What you are not buying is the power to make the water private.
Do you own the river if you own both banks?
No. Owning both banks of a Montana stream, and even owning the streambed beneath it, does not let you exclude the public from the water. This is the point that catches out-of-state buyers hardest, especially people coming from states where you can post a river and keep everyone off it. Montana does not work that way, and it has been settled law for forty years.
Here's the distinction that matters. On a navigable river like the Yellowstone, the state owns the bed below the ordinary high-water mark, and the public may float, wade, stand on the bottom, and fish through your property. On a smaller, non-navigable stream where you do own the bed, the public can still float and recreate on the water, but their contact with your privately owned bed is limited. A person floating through water over a privately owned bed generally cannot pull over to your bank, get out to wade, or drop anchor. They pass through on the water itself.
So the honest framing for a buyer is this. You can own the dirt on both sides and the gravel underneath, and a drift boat full of strangers can still float past your back porch on a July afternoon, legally, as long as they got to the water somewhere other than across your land. If that idea bothers you, frontage may not be the right buy, and it's far better to know that now. If it doesn't, you're in good company with most of the people who own water in this state and consider the tradeoff more than fair.
What exactly is the "ordinary high-water mark," and how do you find it?
The ordinary high-water mark is the line that flowing water leaves on the land by covering it often enough and long enough to leave physical evidence. The statute describes it as the line where the water's presence has changed the character of the ground, stripping terrestrial vegetation and washing the soil, so that the area below looks distinctly different from the bank above.
In practice, it's easier to read on the ground than it sounds on paper. Walk a stream bank in Montana and you can usually see it: the point where grass and brush give way to washed rock, scoured soil, and the debris line that spring runoff leaves behind. That line, not the current edge of the water in low August flows, is the boundary of the public's recreational use. The public's rights run up to that mark on both sides.
This matters for a frontage owner because the high-water mark, not the waterline, defines where your private ground begins for the purpose of public use. The strip between the summer waterline and the high-water mark is open to recreational use even though it may be dry land most of the year. When you walk a property you're considering, walk that line. Knowing where it sits tells you exactly how much of your bank the public can legally stand on.
What can the public legally do on the water through your land?
Within the ordinary high-water mark, the public can fish, hunt, swim, float, wade where the bed is public, and pursue other water-related recreation as they move along the stream. The law defines recreational use broadly, and it covers most of what people come to Montana water to do.
Specifically, the recognized recreational uses include fishing, hunting, swimming, floating in small craft and other flotation devices, boating in motorized craft where not otherwise prohibited, paddling, and related water-based pleasure activities. A floater drifting the Yellowstone can fish your frontage. A wader on a navigable stretch can stand on the state-owned bed and cast. Someone can swim through the deep bend below your house. None of that requires your permission, because the recreational right belongs to the public, not to you to grant.
There are limits on how far this goes onto your land, and we'll get to those. But the operating assumption a buyer should hold is simple: anything reasonable that people do on or in the water, between the high-water marks, the public can do as they pass through, whether or not you like it on a given day.
What can the public not do, and where do your rights as the owner hold?
Your rights hold firmly above the ordinary high-water mark and across the rest of your property. The public cannot leave the streambed and water corridor to picnic on your lawn, camp in your trees, build a fire on your bank, or cross your fields. The recreational right is a right to use the water and the area below the high-water line, not a license to wander your land.
The clearest landowner protections are these. The public cannot cross private property to reach the stream without permission. They cannot enter land that is posted against trespass. On smaller streams where you own the bed, they cannot get out and wade or anchor on your bottom. They cannot remove your fences, damage your property, or harass your livestock. And certain activities that the original law treated more cautiously, like big-game hunting, overnight camping, and placing duck blinds within the high-water mark on smaller waters, carry tighter restrictions. The lays out these rights and responsibilities in detail, and it's worth reading before you buy.
The honest balance for a buyer: the law gives the public the water, but it gives you everything else, and it backs your privacy above the high-water line with real teeth. Most owners find that the line between "the public's water" and "my land" is clearer and more defensible than they feared before they understood it.
How does the public legally get to the water if not across your land?
The public reaches Montana streams through three legal doors, none of which is your property: designated fishing access sites, public bridges and county road rights-of-way, and adjacent public land. The law gives the public the water, but it pointedly does not give them a path across private ground to get to it.
Montana Fish, Wildlife and Parks maintains on rivers, streams, and lakes across the state, and these are the most common put-ins and take-outs. The second door is bridges and county roads, which we'll cover next, because that one matters most to frontage owners. The third is public land, where a river or stream runs through or alongside national forest, BLM, or state ground that the public can already legally occupy.
For a buyer, the practical question is where the nearest legal access points sit relative to your frontage. A property with a fishing access site or a county bridge just upstream will see more float and wade traffic than a remote stretch with miles of private land and no public put-in nearby. Neither is better or worse in the abstract. It depends on whether you want solitude or don't mind company, and it's something you can map before you buy rather than discover after.
What does the bridge and county-road access rule mean for frontage owners?
Public bridges and county road rights-of-way are legal access points to the water, and as an owner you generally cannot block passage where a county road crosses the stream. A 2009 state law, House Bill 190, confirmed that the public may reach surface waters from public bridges and county road rights-of-way, and that landowners and the state must work out reasonable passage around fences at those crossings, often with a gate, stile, or roller.
This has been one of the most litigated corners of the law, and it's still being defined in court. In a long-running Madison County case over the Seyler Lane bridge on the Ruby River, a on both the upstream and downstream sides, giving the public a usable width to get from the bridge to the water. County road rights-of-way are typically 60 feet wide, and that public easement is what allows lawful entry at a crossing.
If you're buying frontage near a county bridge, assume the public can and will use it to reach the water. That's not a defect in the property, it's how Montana access works, but it's a fact worth pricing into your expectations. A bridge crossing on or near your boundary means a steady, legal trickle of anglers and floaters, particularly in summer.
What happens when an owner blocks the stream? A recent local example
When an owner illegally blocks a stream, the public, conservation groups, and Montana Fish, Wildlife and Parks push back, and these days they usually win. The most instructive recent case happened on the West Boulder River, in the kind of country Legacy Lands works every day.
In spring 2025, the owner of a property formerly known as the Brokaw Ranch, sold in 2018 and held by Burnt Leather Holdings, LLC, along with no-trespassing signs aimed at keeping the public out of the water. The Public Land Water Access Association and the Park County Rod and Gun Club challenged it. After negotiations led by an FWP regional supervisor, the dispute was resolved by May 2026: the landowner raised the cross-stream fencing, installed a gate, and posted signage clarifying the public's access rights, with the outcome resting on Montana's right-to-portage provisions.
The lesson for a buyer is twofold. First, you cannot fence the public out of a stream within the high-water mark, even on land you fully own, and attempting it invites a fight you will likely lose. Second, you can fence for legitimate reasons, livestock control above all, as long as you provide lawful passage. If you buy frontage and inherit fences that cross the water, learn the difference between a stock fence with a proper passage and an illegal barrier, because the responsibility becomes yours at closing.
How is this different for a big river versus a small creek?
The same up-to-the-high-water-mark principle applies to both, but the practical reach of public use is broader on a large floatable river than on a small creek. The difference comes down to navigability and bed ownership, and it changes what the public can actually do on your particular water.
On a navigable river such as the Yellowstone, the state owns the bed, and the public can float, wade, stand, and fish across the full width below the high-water mark. On a small, non-navigable creek where you own the bed, the public retains the right to use the water for recreation, but their lawful contact with your bottom is limited, and many of the activities people associate with a big river simply don't happen on a two-foot-wide spring creek. A smaller water also carries tighter limits on things like hunting and camping within the high-water mark.
For a buyer, this means the type of water you're considering shapes how much public presence you'll actually see. Frontage on a famous floatable river comes with real, regular traffic in season. A small headwater creek with no public access point nearby may see almost none, even though the same law technically applies. When you evaluate frontage, look at the specific water, its navigability status, and where the public can legally enter, not just the romance of "river frontage" on the listing.
What about floating, portage, and people passing through?
The public has the right to float through your property and to portage, meaning to leave the water briefly to walk around an obstacle, as long as they do it in the least intrusive way possible. Portage is the one situation where the law lets a recreationist legally step above the high-water mark onto private land, and it's narrowly drawn.
A floater who encounters a barrier, a diversion dam, a fence, a logjam, or a waterfall, may go around it on the bank, but must choose the route that does the least damage to your property and your rights, and must return to the water as soon as they reasonably can. They cannot use portage as an excuse to linger, picnic, or wander. The right-to-portage provisions were central to resolving the West Boulder River dispute described above, and they're a standing feature of how floating works on Montana water.
If your frontage includes a natural or man-made barrier, expect that floaters will occasionally portage around it across the edge of your land. It's legal, it's limited, and in practice it's rarely a problem with reasonable people. It's simply part of owning a stretch of water that the public has a right to travel.
How does stream access connect to hunting and public-land access near your property?
Stream access is one piece of a larger Montana access picture, and the same forces shaping public access to land are active right now in the corridors where Legacy Lands works. If you're buying for privacy or for sporting use, you should understand how the water access on your property connects to the land access around it.
Two current developments matter. First, public-land access by "corner crossing," stepping from one piece of public land to another at a shared corner without touching private ground, got a major boost when a that October. That ruling binds the states in the Tenth Circuit, not Montana, so corner crossing here remains a legal gray area, and Montana has more than 900,000 acres of "corner-locked" public land. Hunters have already , so expect this to keep moving.
Second, closer to home, the long fight over trail access in the ended with a 2024 appellate decision and a land exchange, the East Crazy Inspiration Divide deal, that unlocked more than 2,200 acres of public land and set up a new trail system. The takeaway for a buyer: access law in Montana is active and contested, and a property's value and character depend partly on how the public reaches the land and water around it. Montana FWP's , which opened more than 500,000 acres to hunters in our region alone in recent years, is another moving piece worth understanding if you hunt or value private quiet.
How should you do due diligence on access before you buy river frontage?
Before you buy frontage, map the access reality of the specific property: where the high-water mark sits, where the public can legally enter, what fences and barriers you'll inherit, and the navigability status of your water. Access is a due-diligence item exactly like water rights or a septic approval, and it's one that too many buyers skip until it's too late.
Work through this checklist with your broker before you write an offer:
Walk the high-water mark on both banks so you know precisely how much of your bank is open to public recreational use.
Locate the nearest legal access points, fishing access sites, county bridges, and adjacent public land, upstream and downstream. Their proximity predicts how much traffic you'll see.
Identify every fence or barrier crossing the water and determine whether it provides lawful passage or is an illegal block you'd be inheriting, with the liability that comes with it.
Confirm whether your water is navigable, because that determines bed ownership and how far public use extends onto the bottom.
Check the property's own legal access to the water and to a public road, a separate question from public access, and one covered in our guide to access roads and easements on Montana rural property.
Ask about history. Has there been an access dispute on this stretch? A property with a recent fight, like the West Boulder, comes with a paper trail and sometimes lingering friction.
A broker who knows the water can answer most of these from experience and verify the rest. This is precisely the kind of ground-level knowledge that separates buying frontage you understand from buying a surprise.
Does stream access raise or lower the value of frontage property?
In our experience it does both, depending on the buyer, and the honest answer is that Montana's access culture is part of what makes the water worth owning in the first place. Stream access can feel like a cost to a buyer who wanted a private fishing kingdom. It's a benefit to nearly everyone else, and to the long-term value of the land.
Here's the balanced view. Frontage on famous water still commands a strong premium in this market, public access and all, because live water is the single biggest driver of land value in this part of Montana, and the supply of it cannot be expanded. The access law hasn't suppressed those values over forty years; if anything, the health of Montana's public fisheries, which the access law helps sustain, is part of why people pay for proximity to them. A buyer who wants total exclusivity may be happier with a private pond or a spring creek with limited public reach than with frontage on a blue-ribbon river. A buyer who wants to live on great water and doesn't need to own the public out of it tends to feel they got the better end of the deal.
The point is to buy with your eyes open. Frontage in Montana means sharing the water and keeping the land. For most people who fall for this country, that's not a compromise, it's the arrangement that keeps it the kind of place worth owning. If you understand that going in, river frontage remains one of the most rewarding things you can buy here, and one of the most durable. For more on what holds land value over time, see our look at whether ranch land in Paradise Valley is still a smart buy, and if you're new to the state, our rundown of what surprises out-of-state buyers most about Park County covers stream access among the rest.
Frequently asked questions
Can I stop people from fishing the river that runs through my Montana property?
No. If the water is a natural, flowing stream capable of recreational use, the public can fish it up to the ordinary high-water mark even where it crosses your land, as long as they reached it legally. You own the banks and often the bed, but not the right to exclude anglers from the water itself.
Can the public walk across my land to get to the river?
No. The Stream Access Law gives the public the right to use the water, not to cross private property to reach it. They must enter from a fishing access site, a public bridge or county road right-of-way, or adjacent public land. Crossing your land without permission, or entering posted land, is trespass.
Do I own the streambed if I buy river frontage?
It depends on whether the water is navigable. On navigable rivers like the Yellowstone, the state owns the bed below the high-water mark. On smaller non-navigable streams, you may own the bed, which limits how the public can use the bottom, though they can still float and recreate on the water itself. Confirm navigability before you buy.
What is the ordinary high-water mark, and why does it matter?
It's the line flowing water leaves on the land by covering it long enough to scour the soil and strip vegetation, visible as the boundary between washed rock and the vegetated bank. It matters because the public's recreational rights run up to that line on both banks, so it defines how much of your bank is open to public use.
Can I put a fence across a stream on my own property?
Only if you provide lawful passage and don't block the public's recreational use within the high-water mark. You can fence for livestock control, but a fence that illegally blocks the stream, as happened recently on the West Boulder River, will draw a challenge from access groups and FWP, and you'll likely have to modify it. Inherited fences become your responsibility at closing.
Does Montana's stream access law apply to creeks, or just big rivers?
It applies to natural, flowing streams capable of recreational use, including many small creeks, not just large rivers. The up-to-the-high-water-mark principle is the same, but the practical reach of public use is narrower on a small creek, especially where you own the bed and no public access point sits nearby.
Has the stream access law changed recently?
The core law has held since 1985, but its edges are constantly tested in court. A 2025 ruling defined the public easement width at a contested Ruby River bridge, and a 2025–2026 West Boulder River dispute reaffirmed that owners can't fence the public out of a stream. Related access fights, including corner crossing and the Crazy Mountains, are active. Verify the current state of any specific dispute before relying on it.
Should stream access stop me from buying river frontage?
Not if you understand it going in. Frontage means sharing the water and keeping the land, and live water remains the strongest driver of land value in southwest Montana. Buyers wanting total privacy may prefer a spring creek or pond with limited public reach. Buyers who want to live on great water generally find the tradeoff well worth it.
Legacy Lands Real Estate is a Montana brokerage with offices in Emigrant and White Sulphur Springs, specializing in ranch, land, and mountain properties across Park County and southwest Montana. Our team of brokers and agents, many of them multi-generational Montanans, brings firsthand experience in ranching, land stewardship, and rural property to every transaction. Every piece of land has its own history. We help buyers and sellers find the right match. Contact us at (406) 848-9400 or visit legacylandsllc.com.
Legacy Lands Real Estate
1106 West Park St., Suite 20 #169
Livingston, MT 59047
(406) 848-9400
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