Boulder River Beauty

Photo by Ryan Turner of Ryan Turner photography and angler Reno Walsh. The Boulder River originates in the Absoraka/Beartooth Wilderness Area at a elevation of 8,800 feet just south of Big Timber where it flows north in the Boulder River Valley. It flows 61.8 miles (45 air miles) north through the Boulder River Valley into the Yellowstone River at Big Timber at a elevation of 4,000 feet. This is a look at Montana at its best with a River Running Through It!
The Boulder River is appropriately named, as bread loaf sized boulders can be seen lining the river bed through its crystal clear waters. The beautiful Boulder River Valley is worth the drive to just view the magnificent scenery. The Boulder River divides the Absoraka Mountain Range and the Beartooth Mountain Range and is an edge geological area, therefore giving it a unique look and feel. Three forks of the Boulder River, West Boulder River, Main Boulder, and East Boulder River all converge near McLeod and then flow 20 miles until it reaches the Yellowstone River at Big Timber.
One of the best known scenic attractions on the main Boulder is the Natural Bridge, a rock formation through which the river falls before emerging into a beautiful 105 foot waterfall. The falls creates a barrier to all fish. There are no species of fish above the falls except Rainbow and Brook trout. The fish population below the falls consists mainly of Brown and Rainbow Trout, and Whitefish.
You can find excellent recreation opportunities on the Boulder River including Kayaking, Floating, and Fishing. You can also combine activities by Camping, Hiking, and Hunting in the Boulder River Valley.

Fishing the Boulder River

The Boulder River is a Blue Ribbon trout river where you can find quality rainbow, cutthroat, brook, and brown trout fishing. It provides more than 50 miles of what many believe is the finest trout fishing in the state. Most fishermen fly fish the boulder river, but take along your spinning rod and you will not be disappointed.
All streams on the Absaroka Range have "boulder bottom" and consequently very seldom are discolored even during spring runoff. The Boulder is of unusual purity and many people have no reluctance to drink the water even as far downstream as Big Timber, which gets its ample water supply from the stream.
There are good populations of rainbows in the upper river and a solid mix of browns and rainbows on the lower portion. Trout up th 10 pounds have been caught in the Boulder. Fly hatches are quite heavy, and fish really key in on the hatch. Caddis, mayflies, stoneflies are commonly fished in March, April, and May. Salmonflies and green drakes come of as the water begins to build in May. Watch for PMDs in July and August, along with terrestrials like hoppers and ants. In the fall some awfully large brown s move out of the Yellowstone and into the Boulder for the spawn. Try large weighted streamers at this time. There are many public accesses along the Boulder, one about every 8 miles. Access the the river is not diffucult, as the road parallels the river and signs point out the numerous access points.
The upper river can be described as a medium-sized stream that cuts through a glacial valley. It has a steep gradient that is laced with lots of boulders providing classic pocket water action. It has wide, rocky riffles that fish move into when the weather warms, and it provides a few glassy slicks where delicate dry flies are a must. The boulder river is open all year, with a two trout limit and only one over 13 inches. There is quite a bit of private land along the Boulder River Valley, but Montana laws give fishermen access if you stay below the high water mark. Since the Boulder River is not an ideal river to float fish, bring your waders and walk the river. A walking stick is recommended, as the bottom is rocky and can be hard to navigate.

Floating the Boulder River

You can float the lower portion of the Boulder River below the Natural Bridge Falls. There are several access points that parallel the road up the Boulder River Valley, so access is easy. The lower sections of the river takes an intermediate level raft or whitewater canoe skilled person to navigate. Floating on the Boulder is can be tricky as it is fairly shallow in the summer months and high during the spring runoff. Some people even take an inner tube and float sections. The lower section starts at 22.7 miles up from the Yellowstone River and ends at the confluence of the Yellowstone and the Boulder at Big Timber. If you are floating the river in a vessel, it is recommended that you use a raft or whitewater canoe.

Access to the Boulder River

There are many public accesses along the Boulder, one about every 8 miles. Access the the river is not difficult, as the road parallels the river and signs point out the numerous access points.
A number of campgrounds are located along the river, both private and public. The Boulder Road (Hwy 298 toward McLeod up the Boulder Valley) is paved for 30 miles and then turns into gravel road for the next 20 miles. Campground access roads to the Boulder Campgrounds south of Big Timber can handle larger vehicles. Parking spurs are also available for large vehicles. Camping areas have tent pads, fire grates, picnic tables, and restrooms in some areas. The campgrounds have easy access to good fishing and hiking trails in both non-wilderness and wilderness areas in the Gallatin National Forest.

Boulder River Statistics and Flow Information

Drain Area: 523 square miles
Average Flow 582 cfs
Max Flow 9,840 cfs
Min Flow 10 cfs
Gradient (drop) 4,800 feet in 61.8 miles
Lower Float Gradient 900 feet in 22.7 miles
Clarity Clear in all months-
clowdy in the height of
spring runoff from April thru June
Water Temperature Jan. 32 degrees
April 52 degrees
July 61 degrees
Oct. 54 degrees
Maps USFS - Gallatin NF -
Custer NF (Beartooth Division lower portion only)
Dangers 105' Waterfall at Natural Bridge Milepost 32.9