Field Trip Friday: Natural Bridge Falls Montana

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On Fridays, I (sometimes) post about our field trips exploring near home. Pack a lunch and hop in the car– here’s what you need to know to plan your own field trip.

This article is based on many visits to Natural Bridge Falls, Montana. I’m putting all the details together so you can plan your own trip to Natural Bridge, Montana. Make sure to read to the bottom for information about determining the stream flow — that affects whether you will find a waterfall or an underground river emerging from rock.

There is no Natural Bridge State Park in Montana, though I found at least one website claiming there is. There is a Natural Bridge Trail in Yellowstone and a National Monument in Utah. In fact, there are natural bridges all over the world.

The place I am talking about here – Natural Bridge Falls  Picnic Area is managed by the Forest Service. It’s on the Boulder River about 25 miles south of Big Timber, Montana. And there isn’t a natural bridge there anymore.

two boys looking at Natural Bridge Falls Montana


The Boulder River Valley is one of my favorite places in Montana. It is the largest watershed in the Absaroka drainage and backs up to Yellowstone National Park. The mountains on both sides of the valley stretch up and are often snow capped. The farther you drive down the valley, the more stunning it becomes.

The stretch between Big Timber and Natural Bridge Falls is wide and rolling. Family ranches (and Tom Brokaw’s place) dot the landscape. The Boulder River winds through the valley, though it is mostly on private property and hard to access until you cross the National Forest boundary.

Two boys standing in the Boulder River at the Boulder Forks Fishing Access site montana
Boulder Forks Fishing Access

The Boulder Forks Fishing Access Site (16 miles south of Big Timber) is a good place to cast a line for native Yellowstone cutthroat trout, mountain whitefish, and wild brown and rainbow trout. Fishing is best in summer and fall, but open year-round.

yellow flowers at Natural Bridge State Park

Beyond the Natural Bridge, the road continues another 25-ish miles. It’s gravel and rutted and slow going. It’s mostly National Forest land and there are several campgrounds plus plenty of non-developed places to camp. Additionally, there are a few church camps and other private inholdings.

You can access trails on both sides of the valley that lead into the Absarokas, Beartooths, and Yellowstone National Park.

back of a man and a camera in front if an underground river rushing out of a rock

Notes from August 2021 Visit to Natural Bridge Falls, Montana

boy next to waterfall in montana

In late summer, the water level is pretty low, but according to Anders, who swam over to the waterfall, it is still icy cold.

Anders was able to wade across the pond at the bottom of the falls, but it came over his shoulders and he is 6 feet-5 inches tall, so that’s a swim for most of us. The rocks aren’t slippery and despite how it looks in this photo, it is pretty safe for a teenager or adult to climb around over there. (In my opinion, you decide your own comfort level). 

Notes from May 2020 Visit to Natural Bridge, MT

We visited the picnic area and falls on Mother’s Day during the 2020 pandemic and it was more crowded than I’ve ever seen it. Normally we don’t visit on weekends. That said, when we got to our favorite place below the falls, we had it to ourselves most of the hour we hung out down there.

In addition to folks reading interpretive signs and snapping photos of the falls from the East Rim Trail (about a 1/4 mile from the parking lot), there were a couple of small groups rock climbing.

I also love looking for wildflowers here. They seem to come out earlier than in other places. When we visited this time, the Boulder River was just under 2,000 cfs after a week of cool weather. Keep reading to find out more about how to know if the waterfall will be flowing over the top of the limestone.

Notes from May 2014 Visits to Natural Bridge Falls (with waterfall!)

Natural Bridge Falls is about an hour from here, but it’s a place I seem to forget about. I don’t think we’ve been there in four years. We made up for it this year with two visits.

We met our friends April, Summit, and Journey at the falls a couple Mondays ago. The water was strong, but not strong enough to make a waterfall.

The thing about the falls is that it is only a waterfall when the river is really high. Until then, the Boulder River drops into a hole in the limestone and comes out mid-cliff downstream. Still very cool.

The falls gets its name from the natural bridge that once spanned the river, but collapsed in 1988.

When you visit at high, but not high enough, water, it comes gushing out of that hole like a fire hose.

We walked around the short trails, then dropped down to the stream bed between where the river disappears and reappears. The kids had a blast dipping their toes in puddles, climbing over rocks, and discovering fossils. We found shell fossils all over the place and corals that looked like lizard skin.

(We kind of hoped it was lizard skin, but April sent a photo to a scientist at Montana State University who identified it as coral. Still cool.)

Back home, and after some more research by April and another friend we ran into at Natural Bridges, Sara, we learned that the river needs to near 5,000 cubic feet per second to go over the top of the falls. It was under 2,000 cfs when we thought there was so much water.

April and family went back the next Saturday and sent pictures of the now-full waterfall. We had to go. Sara and I met the following Monday when the water was just under 5,000 cfs. That was May 26 and after that it went even higher.

We hiked to the bottom of the falls and sat in the mist for an hour. Despite the busy parking lot, we were the only ones down there save for a couple that popped down for a couple minutes. It was the first time the boys and I had ever seen the waterfall. That roar of water was well worth a second trip.


Plan Your Own Trip to Natural Bridge, Montana

Before you go, check the U.S. Geological Survey’s real-time water data for the Boulder River at Big Timber (USGS 06200000). When flows get close to 5,000 cfs, it’s time to go. Or go whenever, it’s a beautiful spot no matter the water level.

What: Natural Bridge Falls (maintained by the U.S. Forest Service)
Why: 100-foot waterfall (or disappearing river), wildflowers, trees, fossils, picnicking
Where: On the main branch of the Boulder River just south of McLeod (26 miles south of Big Timber) in the Custer Gallatin National Forest. Take Highway 298 south from Big Timber. The road is paved until just before the Natural Bridge Falls parking are where it turns to gravel. Access is year round.
Who: You! The Custer Gallatin National Forest maintains a couple picnic tables, pit toilets, trails (including handicap-accessible route), and viewing platforms with interpretive signs.

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Greycliff Prairie Dog Town State Park and the Big Timber Park, Spring 2010

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2 thoughts on “Field Trip Friday: Natural Bridge Falls Montana”

  1. JoDee Palin

    Thank you for this. I asked my boyfriend to go on a date with me this Sunday and he said yes!!! We are going on Sunday. I am so excited.

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