Custom trip plan

Wild trout, southwest Montana

Bozeman, Montana. Thursday, October 8, 2026. 5:30 AM to 2:00 PM. Wade fishing only.

A sample plan. Written as a real plan for these dates, to the same standard as a paid one, so you can see exactly what you get. The trip has been and gone, so the conditions below are what the weather actually did. It was written for a first visit, wading, with no guide, so it ranks three rivers on access and flow rather than naming one. How to get one for your own trip.

Which fish to go after

Fish for rainbows, and treat a big brown as a bonus you earn in the first hour rather than the thing you plan around.

The clean reason is the calendar. Rainbows spawn in spring, so in October they are simply feeding, and they are a dawn fish whose best hours land inside your window. Browns spawn in autumn, which makes October both their most aggressive month and the month where chasing them raises a question you told me you care about.

The engine agrees for a less interesting reason: browns are a dusk species, and your day ends at two. Scored across your actual hours rather than the whole day, rainbows come out ahead at every river in this plan, by a consistent margin.

None of that means avoiding browns. A pre-spawn brown holding in main-river water is a legitimate and very good target, and the first hour with a streamer is your best shot at the larger fish you asked about. What it means is not fishing to the ones that have already moved onto gravel, and the difference is easy to see once you know to look.

Rainbow Trout

primaryengine range 45 to 65°F, ideal 55°F
For it
  • A spring spawner, so nothing about October complicates targeting them. No redds, no ethical question, no seasonal penalty in the model.
  • A dawn feeder whose strongest hours sit squarely inside your window, while the day is still cool.
  • In its autumn feeding period through October, so the model lifts it rather than docking it.
  • If the water figure on this page sits near the warm end of its range, expect active fish in the morning and sluggish ones by afternoon, which is the shape of your day anyway.
Against it
Nothing, which is why it leads.

Brown Trout

opportunisticengine range 50 to 70°F, ideal 58°F
For it
  • October is the month for a genuinely large brown. Pre-spawn fish are aggressive and will chase a streamer they would ignore in August.
  • While the water stays above their spawning band the model treats them as pre-spawn and feeding rather than locked up. A front that drops it changes that, and the accounting above will show the shift.
Against it
  • A dusk feeder. Its best hours are after dark from your point of view, and the back half of your window is its worst.
  • Spawning starts late this month and runs into November. Fish that have moved onto shallow clean gravel should be left entirely alone, which rules out some of the most obvious-looking water.

The call

Thursday, October 8, Bear Trap Canyon, lower Madison

Be on the water by 7:04 AM, in the dark. The engine's best hour for Rainbow Trout inside your window is 8a. Your strongest run is 8a to 11a.

A guide, not a guarantee. Conditions recomputed Oct 9 at 5:23 PM, and again every time you open this page. Tide and daylight are exact at any range; the weather layer firms up as the date gets closer. What that means.

Your day, hour by hour

Thursday, October 8
A+
99 / 100
YOUR HOURSMOONHOURLYgoodyour best 3 hourssunrise 7:34a4a6a8a10a12p2p
  • Moon major
  • Moon minor
  • Sunrise
  • Before first light
  • Your hours

The day came in where we called it.

We said, on Oct 7
A+ 97, best 8a to 11a
What the weather did
A+ 99, best 8a to 11a

The left is a record of what this page published before the trip. The right is the same engine run again on the weather that actually happened. Neither was adjusted to suit the other.

Good hours
5h, tight
Wind
3 to 17 mph (gust 24)
Water
58°F (measured)
Madison River bl Ennis Lake nr McAllister MT, 2 mi
Flow
1,160 cfs (10th percentile, very low)
USGS Madison River bl Ennis Lake nr McAllister MT, 2 mi
Pressure
falling

Stable weather pattern: consistent conditions. Favorable S wind. Fall feed-up for Rainbow Trout: aggressive feeding.

Fresh water, so no tide. The hourly line is the engine’s conditions score for this species, hour by hour.

Most years, these dates

10 years of reanalysis for this calendar week, taken at your starting mark during your own hours: 630 hours across 70 days, 2016 to 2025. This is not a forecast for your week and cannot be one. It is what this week has done.

Where the wind comes from

  • N15%
  • NE2%
  • E1%
  • SE5%
  • S64%
  • SW11%
  • W1%
  • NW1%

The prevailing wind through your hours is S, carrying 64% of them and dominating 55 of the 70 days sampled.

How hard it blows

Under 10 kn
78%
10 to 15
22%
15 to 20
0%
20 and up
0%

Median 6.4 kn, with one hour in ten above 11.5 kn. 0 of 70 days averaged 15 kn or more right through the window, which is about where a big bait stops holding and a small boat stops being comfortable.

Air through your hours runs 28 to 59°F, median 44°.

ERA5 reanalysis through the Open-Meteo archive, read 2026-10-07, checked against the nearest ocean anemometer before any of it was published. Wind and air only: a reanalysis on a 25 km grid does not resolve a thunderstorm, so its rain and storm fields would read reassuringly low and be wrong, and they are left out rather than softened. The air figures run about two degrees warmer than the model that produces the forecast on the rest of this page, so read them as a range rather than against a grade.

The outlook

Fish early and go home early. Whatever the strip above says on the day, your window covers the part of an October day that is reliably good, and if it comes in warm and bright, as the first forecasts had it, the fishing advice and the fish-welfare advice are the same advice.

Your first two hours are not fishing hours. Sunrise in Montana in October is a good deal later than people expect, and on your date it is well after seven, so a 5:30 start puts you on the water two hours before you can see what you are doing. That is not wasted time, it is exactly the drive and the walk in. Leave at half past five, be at the trailhead around twenty past six, walk in as it gets light and have a fly in the water by quarter past seven. The strip above prints the engine’s strongest run for your day; set your watch by that rather than by this paragraph, and expect it to want you fishing early.

Read the grade with one eye open. If the page shows an A or better, that is the engine being honest about a warm day in a good season. Look at the factor list underneath and read what it says about air temperature and sky, and there is a section further down that shows exactly how much of the grade comes from those measured factors and how much from the engine’s beliefs about the season. Read it before you trust the letter. The grade is not wrong, it is answering "is this a nice day to be on a river". For "will the fishing be easy", trust the factor list and the hourly curve.

Your August worry turns out to be live in October. You said you did not want to fish if afternoon water got unsafe, which is normally a July question here. Check the water figure and the forecast high on this page: an October afternoon here can warm enough for the fish to feel it even when nothing comes near the state’s restriction threshold. Carry a thermometer. The plan has you off the water before it matters.

One more thing a search will not tell you: the main October hatch wants weather you are not getting. Blue-winged olives are what southwest Montana rides in autumn, and they come off on grey, damp, still days. If your date comes in clear and dry, as the early forecast had it, that does not ruin the day, but it does change what to tie on: the fly advice below is written for a bright day, and the triggers say what to do if cloud arrives.

One line about wind, because the number is unusual enough to be worth it. Over ten early Octobers for your own hours, the wind in this valley was from the south on 55 of the 70 days sampled and 64 percent of all window hours. That is the Gallatin running the air up and down its own axis rather than any weather system, and it is light: 78 percent of window hours under 10 knots and not one day in ten years averaging 15. On this trip the wind is a casting consideration on the open Yellowstone and nothing more.

Where to fish

Start here: Bear Trap Canyon, lower Madison

Madison County, via Norris, about 55 minutes

Nine miles of roadless canyon below Ennis Lake, inside the Lee Metcalf Wilderness, with a trail along the east bank and pocket water, runs and deep slots between cliff walls.

  • It scores best of the three across the hours you actually have, not just across the day. That is the comparison that matters when your window ends at two.
  • It is the answer to two of your constraints at once. You asked to avoid the crowded access points and said you would walk up to a mile and a half, and this is the one place nearby where walking genuinely buys you solitude: there is no road in, and the further up the trail you go the fewer people there are.
  • Wilderness canyon water on public land, so the stream access question does not even arise. You walk in from a public trailhead and fish.
  • Pocket water and defined slots suit a wade angler with a five weight far better than a big open river does. You can read it, and you can cover it from the bank.
Wants
No tide. Fish the seams, the slots and the heads of runs, and the first two hours of light.
Out of play in
Nothing weather-wise on a day like this. Its cost is the walk and the drive, and the trail is rough enough that it is not somewhere to be hurrying back along in the dark.

Footing. Rattlesnakes and poison ivy along the trail, and a canyon where the bank is often rock rather than gravel. Wading boots with grip, watch where you put your hands when scrambling, and do not wade out to reach a rise if the current is pushy. This is also bear country.

Public access. The BLM describes the Bear Trap Canyon Unit of the Lee Metcalf Wilderness as the first wilderness area managed by the BLM, 6,347 acres, with the nine-mile Bear Trap National Recreation Trail following the river the length of the canyon, hiker access at the north end only, and the Kitchen Sink rapid rated Class IV to V. Fishing is named among the activities. Bureau of Land Management, Lee Metcalf Wilderness, Bear Trap Canyon Unit, read 2026-10-03.

Before you go. Outside Bozeman’s trail guide gives the way in: from Four Corners drive 21 miles west on Highway 84, turn left onto Bear Trap Road just before the Madison River bridge, and the trailhead is about three miles in at the end of the gravel. The same guide says to carry bear spray and watch for rattlesnakes and poison ivy, which is worth knowing before you step off the trail to reach the water.

Backup: Yellowstone River, Paradise Valley

Livingston and south, about 40 minutes

The largest river in the plan, running through Paradise Valley with long riffles, deep pools and defined runs between gravel bars.

  • When the flow is low, as the gauge had it when this was written, this river is exactly what a wade angler wants: a level inside the band local anglers give for wadeable flows, which is not true for most of the year. Check the flow figure on the day card.
  • It carries the biggest fish of the three, and the autumn streamer fishing here is what the river is known for.
  • Numerous public fishing access sites along the valley, so if one is busy the next is a few minutes down the road.
  • Low clear water concentrates fish into recognisable holding water, which makes a big river readable in a way it is not in June.
Wants
No tide. Fish the inside of gravel bars, the drop at the back of riffles and the seams along deeper runs.
Out of play in
Nothing on this forecast. Its real limitation is size: even at low flow it is a big river, and a wade angler fishes the edges and the gravel bars rather than crossing it.

Opens 5:00 AM, closes 10:00 PM. Your 5:30 AM start is inside that.

Footing. A big, cold, pushy river even at low flow. Wade the inside of bars and do not try to cross to the far bank. A wading staff is worth carrying here and not at the other two.

Public access. Montana FWP lists Carter’s Bridge as a fishing access site on the Yellowstone in Region 3, three miles south of Livingston on Highway 89 then a quarter mile east on Secondary 540, with a toilet and a gravel ramp. Pine Creek is a further public site a few miles up the valley. Montana FWP Fishing Access Site record, Carter's Bridge, read 2026-10-03.

Before you go. FWP installed an automated gate at Carter's Bridge in early 2026 and the site is open 5:00 AM to 10:00 PM (Livingston Enterprise; Montana Outdoor, March 2026), so a 5:30 start works but an earlier one does not. FWP's own record notes limited parking. Your date is a Thursday, so the weekend parking crush should not be a factor.

Backup: Gallatin River, the canyon at Moose Creek Flat

Gallatin Canyon, US 191, about 43 minutes

Classic freestone pocket water in a canyon, small enough to read at a glance and to cross in most places.

  • The most forgiving wading of the three by a distance, and the closest. If time is short or you want to fish rather than drive, this is the one.
  • Pocket water is the easiest river type to fish well on a first visit. The holding water is obvious, you can cover it from the bank, and you move constantly rather than reading one long run.
  • The road runs beside it for miles, so you can look at several stretches before committing, which on an unfamiliar river is worth a lot.
Wants
No tide. Fish the pockets, the pillows in front of and behind boulders and the tailouts of small runs.
Out of play in
Nothing weather-wise. Its drawbacks are that the road access which makes it easy also makes it the most fished of the three, and the fish run smaller than on the Yellowstone.

Opens 7:34 AM, closes 6:55 PM. That is 2 h 4 m after the 5:30 AM start you asked for, so plan the morning around the gate rather than the alarm.

Public access. The Custer Gallatin National Forest publishes Moose Creek Flat Campground in the Gallatin Canyon, 32 miles south of Bozeman on US 191, beside the Gallatin River, with an accessible fishing dock at the river’s edge, and names rainbow, brown, brook and cutthroat trout, whitefish and Arctic grayling as what anglers cast for. Its operational hours are day use only, sunrise to sunset. Separately, Montana stream access law allows use of the bed and banks below the ordinary high-water mark where entry is gained from a public road right of way or access site, and that is what opens the rest of the canyon. Custer Gallatin National Forest, Moose Creek Flat Campground, read 2026-10-04.

Before you go. Two different clocks here, and the difference decides your morning. The Forest Service site is day use only, sunrise to sunset, so you cannot be inside it before first light. The highway pullouts up and down the canyon are not gated and stream access law covers them, so an early start means a pullout rather than this parking lot. Your date falls in the limited-service season, 1 October to 1 December, which the Forest Service describes as no fee and no amenities: the water is open and the facilities are not. Park only in established pullouts, and enter at a bridge, a right of way or a marked access rather than across posted ground. The Porcupine Creek Road to West Fork section carries its own season, the third Saturday in May through 30 November, which covers your date.

Considered and ruled out

2 places were looked at and left out. What settled each one is underneath it.

  • Yellowstone National Park waters. The park is roughly eighty five minutes from Bozeman to the Gardiner entrance, outside the seventy five minutes you gave, and its fishing season ends on 31 October so the window is short. It is a genuinely excellent option on a longer day, and it needs its own park fishing permit on top of anything else, which is worth knowing before you drive there assuming a Montana license covers it. It does not. National Park Service, Yellowstone fishing regulations.
  • The Big Hole and the Beaverhead. Both are famous and both are out. They are beyond your radius anyway, and more importantly drought closures on parts of each were still in force when Montana FWP lifted the summer hoot-owl restrictions elsewhere in September. Restrictions move through the autumn, which is the reason to check the FWP restrictions page in the days before you drive rather than relying on this paragraph. Montana FWP drought and fishing restrictions.

How to fish it

Half five to quarter past seven, getting thereNothing yet

This is drive and walk, not fishing. It is properly dark until past seven, and a canyon trail with rattlesnakes on it is not somewhere to be hurrying in the dark with a head torch. Use the hour. Rig the rod at the trailhead while it gets light so you are not fumbling with tippet at the exact moment the fishing starts.

First light, roughly quarter past to half past sevenWoolly bugger or small sculpin

The short window where a big brown is realistic. Cast across and down, swing it, strip back in short pulls with pauses, and fish the undercut banks and the deep side of a seam. Twenty minutes of this at first light is worth more than two hours of it at ten. Stop when the sun is on the water.

Half seven to ten, the heart of the morningDry-dropper: a Chubby Chernobyl with a Perdigon or pheasant tail eighteen inches to three feet under it

Usually the strongest fishing of the morning, and worth checking against the strongest-run line above. The foam dry is visible in broken water, holds the nymph at depth in pockets, and will genuinely get eaten on a warm bright morning, which is the one thing that kind of day buys you. Fish upstream, short casts, dead drift, two fish from a pocket and move. Cover water rather than flogging one seam.

Ten to midday, as the light hardensSame rig, deeper, or a nymph rig with split shot

The curve is falling now, but there is a solunar feeding period through the late morning that props it up a little, so do not pack up at ten. Lengthen the dropper, add weight, and move off the open riffle into the deeper runs and whatever shade the canyon wall is throwing. Pat’s Rubber Legs on the bottom of a deep slot is the most reliable fish of the middle of the day.

If anything rises at any pointSmall mayfly dry, or an ant

Go finer immediately. Low clear water and hard sun makes fish spooky, so 5X and often 6X, lead the fish further than feels right, and approach from downstream. One good drift from the right angle beats six from the wrong one, and on water this low you usually get one.

Midday to two, winding downHoppers, ants and beetles along the banks

Unusual for October and justified only by a warm afternoon. If the forecast high on this page is in the seventies or better, the heat brings terrestrials back for a few hours, so work grassy undercut banks with something buggy. Check the thermometer while you do it. If twenty minutes of good banks produces nothing, that is the day telling you it is over, and the water temperature will probably agree.

  • Blue-winged olives are the October hatch here and they want grey, damp, windless weather. Your day is the opposite, so do not stand around waiting for a hatch that the forecast has already ruled out. If cloud does roll in, change your mind immediately: a BWO hatch under cloud is the best dry-fly fishing of the autumn and it is worth abandoning any other plan for.
  • Check the flow figure on the day card. If the rivers are running low for the date, as they were when this was written, that is good news for a wade angler on the Yellowstone and the Gallatin and bad news for stealth: low means clear, and clear plus bright sun means spooky. It does not make the lower Madison crossable. Bear Trap Canyon holds Class IV and V water and you fish it from the bank, whatever the gauge says. Long leaders and fine tippet. 5X as a default, 6X for anything rising in flat water, which is lighter than you would fish the same rivers in June.
  • Approach from downstream and stay low. On bright days in low water, the fish see you before you see them, and the single biggest difference between anglers on a day like this is how close they get without being noticed.
  • Carry a thermometer and actually use it. Check the water when you arrive and again mid-morning. If it climbs into the mid sixties, you are into the range where a released trout is less likely to survive, and the right answer is to stop rather than to fish more carefully.
  • Play fish quickly on the heavier tippet you can get away with, keep them in the water, and do not lift one out for a photograph on a warm afternoon. On a day this warm, a long fight is the thing that kills a fish you intended to release.

What should make you change

IfThen
The water reads into the mid sixtiesStop fishing. This is the line you drew yourself and it is the right one. Nothing on this forecast reaches the state restriction threshold, but mortality on released fish starts climbing well before any official number does.
Cloud rolls in, or it starts to drizzleDrop everything and fish small mayfly dries. Grey damp weather is exactly what brings off a blue-winged olive hatch, and on this river system that is the best dry-fly fishing of the season. It would turn an ordinary day into a memorable one.
You find fish paired up on clean shallow gravelLeave them and move. Those are spawning browns on a redd. Do not cast to them and do not wade across the gravel, which crushes eggs whether or not you catch anything. Walk around and fish the deeper water below, where the fish feeding on drifting eggs are both legitimate and often bigger.
Nothing moves to the dry-dropper in half an hour of good waterGo down rather than across. Add weight, deepen the dropper, and fish the bottom of the deepest slot you can find. On a bright high-sun day the fish are usually there and low, not absent.
The access site you pick is fullDrive to the next one. In Paradise Valley they are a few minutes apart, and your date is a weekday so this should be rare. It is not worth crowding somebody on a river with this much water in it.
By about eleven the morning has gone quiet and the sun is hardThat is the forecast doing what it said. You have had the best of the day. Fish the banks with a terrestrial for an hour if you are enjoying yourself, and otherwise call it a good morning rather than grinding out a hot afternoon.

What people have been reporting

Six days out is close enough that a current report will exist by the time you go, and southwest Montana is probably the best-covered fly-fishing region in the country for free daily reports. Several Bozeman and Livingston shops publish flows, hatches and what is working, updated most days. Read one the night before: it is the cheapest possible improvement to this plan, and it will tell you about a hatch or a flow change that nothing here can anticipate.

Daily Montanan, reporting the Montana FWP announcement · Daily Montanan staff · September 10, 2026

Hoot-owl restrictions lifted on the Madison from the Warm Springs Boat Launch to the Jefferson confluence and on the Beaverhead from Selway Bridge to the Big Hole confluence, as water temperatures cooled. Drought-related closures remained in effect on portions of the Beaverhead and the Big Hole. On 3 October FWP’s own closures page showed nothing in force on the Madison, the Gallatin or the Yellowstone, and a drought closure still on one section of the Big Hole.

A news report of an agency decision, so no commercial angle, but restrictions are reviewed continuously and a hot dry spell can bring them back. The FWP closures page linked under the regulations is the one to re-read before you drive.

Source
Regional guide and outfitter October summaries, southwest Montana · Compiled · Seasonal, read 2026-10-02

October described as the month for trophy brown trout, with pre-spawn fish aggressive to streamers and the Yellowstone singled out for autumn streamer fishing. Blue-winged olives named as the primary October hatch, coming off mid-morning and strongest on grey, damp, low-wind days. Brown trout described as spawning in early November, with October the month the largest fish drop their guard and turn aggressive.

Outfitter and guide content, so it is selling the region. The seasonal pattern is reliable; treat any claim about how good it is right now with the scepticism you would apply to any advertisement.

Source

Reports read 2026-10-03.

What is measured, what is not

A plan like this mixes five very different kinds of claim, and they are not equally reliable. They are separated here so you can weigh them yourself.

Every grade, tide time, wind figure and water temperature on this page is computed when you open it, so the page sharpens as the trip approaches rather than going stale. The strategy, the marks, the regulations and the fishing reports are written once and carry the date they were written. Water temperature is held at low confidence more than two days out whatever its source, which matters because it is the largest single factor in the grade. The one block that never sharpens is "Most years": it is a ten-year history and it is the same whenever you open it.

Measured
Sunrise, moonrise and the solunar periods, which are astronomy and exact at any range. A streamflow or water-temperature reading taken at a gauge, where the day card names one.
Forecast or projected
Wind, pressure, cloud and precipitation, from the weather model and firming as the date approaches. Water temperature too, from whichever source the day card names beside the figure; the label there says whether it was measured, modelled or projected.
Typical for these dates
The wind and air figures under “Most years”. 10 years of reanalysis for this calendar week at the starting mark, during your own hours. It says what this week usually does, which is the most anyone can say before the forecast reaches your dates. It is not a forecast for your week, and no grade on this page is computed from it.
Reported by others
The fishing reports above. Dated, attributed, anecdotal, and in some cases advertising. The most recent predates your trip, so treat it as the last known position of the fish rather than a forecast of where they will be.
Angler judgment
Which mark to start at, which lure, how to retrieve it, and every threshold in the change table. Inference from the conditions and from how this species behaves, not output from the engine.

Where the Thursday grade comes from

The factor bars are not the whole score. They are averaged by weight into a starting number, and then the engine applies adjustments that no bar shows: things it knows about the season, the fish and the run of weather before your trip. Those adjustments are normally invisible. Here they are.

The visible factors, averaged by weight
83
Multi-day stability
+7
Turbidity
+5
Visibility
−4
Seasonal state
+4
Day length trend
+2
Forage match
+2
Published
99 A+

This is the engine explaining itself, not a second opinion. Read it as: the weather on its own earns 83, and the rest is what the model believes about the season and the species. If you only trust what was measured, trust the 83.

A worked example of the difference

The flow figure on the day card is a gauge reading, measured, with the gauge and its distance named beside it. Whether that flow is "wadeable" is a judgment local anglers make, and this plan repeats it. The engine’s preference for rainbows over browns across your hours is a computed result of two species profiles and your window, which the accounting above makes visible. Keep the three apart when you decide how far to trust each.

A guide, not a guarantee

What this page promises is narrow and it is kept. Every gate time, fee, rule, closure and report named here points at the page it came from and the date somebody read it. Every number about conditions is computed when you open it, from the sources named beside it. Anything that is neither is marked as judgment, above.

What it does not promise is a fish. Agencies change rules between seasons and do not always announce it, gates get locked for reasons nobody publishes, rivers come up overnight, and a well-read day on well-read water still blanks often enough that anybody telling you otherwise is selling something. Check the regulations and the access yourself before you drive, treat the hazard notes as the serious part of this document, and take the rest as a sourced opinion about where to start.

Regulations and license

Three license pieces, one open season, and a restrictions page that can change in a hot week. The stream access law is generous, and its one condition is how you reach the water. Everything here was read on 2026-10-03. Check it again before you drive: these change, and the consequences of being wrong are yours.

The season is open on your date

These rivers sit in Montana’s Central Fishing District, where the standard season for rivers and streams is open all year. That is the opposite of the Western District next door, which runs the third Saturday in May through 30 November, and it is worth not muddling the two. What does carry dates here is the exception list: the Gallatin canyon from Porcupine Creek Road to the West Fork is open the third Saturday in May through 30 November, which covers your date. Check the specific stretch you end up on against the regulation book, because Montana manages this water by water rather than by blanket rule.

Montana FWP fishing regulations, Central District
Buy the license before you go, and note that it is three things

A non-resident needs a conservation license, an aquatic invasive species prevention pass and the fishing license itself. Bought together, a single day runs about thirty-one dollars and fifty cents and a full season about a hundred and seventeen. Available online from FWP or over the counter in any Bozeman fly shop, which is also the easiest place to ask what is hatching.

Montana FWP, fishing licenses and permits
Montana’s stream access law is the most generous in the country, and it has one condition

You may use the bed and banks of any stream capable of recreational use up to the ordinary high-water mark, whoever owns the land either side. The condition is how you get there: entry must be at a public bridge, a county road right of way or a public access site, never by crossing private ground. This is why the plan names access points rather than stretches of river, and it is the direct answer to your constraint about not crossing private property.

Montana Stream Access Law, as summarised by Montana FWP
Check restrictions the week you go

Montana imposes and lifts hoot-owl restrictions and drought closures through the season in response to water temperature and flow. The summer restrictions near here were lifted in September and closures remained on the Beaverhead and the Big Hole. On an unseasonably warm week that picture can change, and FWP keeps one page current. Read it.

Montana FWP, drought and fishing restrictions
Spawning browns are a conservation matter, not just an etiquette one

Brown trout spawn here from late October into November and hold on redds, which look like clean, pale, swept patches of gravel in shallow water. Wading across one destroys the eggs in it whether or not you are fishing. Montana does not close these rivers for it, so this is on you rather than on the regulations: walk around pale gravel, and leave paired fish alone.

Montana Angler, October fly fishing near Bozeman

The brief this was built from

Goal.
Good-quality wild trout in a scenic river, with a chance at some larger fish. Productive fishing matters more than numbers.
Method.
Wade fishing only, within 75 minutes of Bozeman, Montana. Intermediate fly angler, first visit to Montana.
Style.
Dry flies and dry-dropper where realistic, willing to nymph or throw streamers
Gear this plan assumes
  • 9' 5-weight with floating line, 4X to 6X
  • Chubby Chernobyls and foam attractors, hoppers, ants, beetles
  • PMDs, caddis, small mayfly dries
  • Perdigons, pheasant tails, hare's ears, Pat's Rubber Legs, zebra midges
  • Woolly buggers and small sculpin patterns
  • Indicators and split shot
Constraints respected
  • Public and legal access only, no crossing private property
  • Rivers or larger streams, not stocked ponds
  • No guide
  • Comfortable hiking up to about 1.5 miles
  • Moderate current but no dangerous crossings
  • Would rather avoid the most crowded access points
  • Catch and release, and will stop if water gets too warm to fish responsibly