The Swan River Oxbow Preserve

The Preserve

The preserve is centered within the Crown of the Continent--between the Swan Range to the east, and the Mission Mountains to the west -- where the Swan River flows through a beautiful valley.

The preserve derives its name from a long, curving oxbow in which the Swan River used to flow. The variety of wetland communities create a haven for birds and harbor 5 rare plant populations and two rare lichens. It also provides is vital habitat for grizzlies, elk, moose and deer.

Water: The Essential Element

Most of the preserve lies within a delta formed by the Swan River as it flows north to Swan Lake. The water table is high throughout the preserve due to the flooding and a system of perennial springs and seeps along the eastern border. The high quality water in the preserve is due to its origins as snowmelt from the Swan and Mission mountains.  In late spring and early summer, when the river is high, water flows through the river bed and charges the oxbow pond. In late summer through early spring, water from Lost Creek radiates into the limestone till beneath the preserve. Whether from the river or underground sources, this essential element feeds the meadows, marshes, forests and perennial springs of the preserve.


Grizzly bears use the preserve as a corridor between mountain ranges and feed on native fruits, such as huckleberries, and herbaceous plants in the area. Bald eagles and osprey roost in the trees and feed along the river. Elk, moose and white-tailed deer may also be found on the preserve.

Various aquatic birds are drawn to the water systems of the preserve, including the common loon, mallard, cinnamon teal, ring-necked duck, common goldeneye and spotted sandpiper.

Plant Life

Spruce forest predominates along the southern boundary. A complex of sedge fen and birch carr communities lie adjacent to the spring system. To the west, cottonwood forest dominates the area around the aquatic oxbow. In addition, much of the northwest portion of the preserve is covered by marsh which is flooded throughout most of the growing season. 

Water howellia (Howellia aquatilis) is especially significant. Federally listed as threatened, Howellia is thought to be extinct in California and Oregon and is threatened in Washington, Idaho and Montana. On the preserve, howellia grows in the marshy areas next to the oxbow. An annual plant with white flowers, howellia requires a delicate balance of conditions for its survival. The plant has must be submerged in water to grow and reproduce. But its seed won't germinate under water, so howellia must grow in ponds that are flooded in spring, and dry by late summer or fall. If conditions are too wet, the seeds will not germinate. In drought conditions, the plant won't grow.This population is extremely sensitive to climatic change, soil conditions and disturbance.

Round-leafed pondweed (Potamogeton obtusifolious) grows in the oxbow and adjacent ponds. Northern bastard toadflax (Geocaulon lividum) inhabits the wet spruce forest. Buchler fern (Dryopteris cristata) is found where carr vegetation and spruce forest intermingle. Small yellow lady’s slipper (Cyprepedium calceolus) grows on the preserve.


Since 1989 the Swan River Oxbow Preserve has been the site of a bird banding station. Under the Monitoring Avian Productivity and Survivorship program (MAPS), volunteers use mist nets to catch and band such neotropical migrants as the western tanager, Swainson’s thrush, red-eyed vireo and Lincoln’s sparrow. Through this research The Nature Conservancy hopes to contribute to the understanding of bird population trends worldwide.  

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Planning Your Visit

This is wild land, not a park. In this wetland, vegetation grows quickly and the trail can become hard to find in places. There is some planking in very wet spots, but prepare to encounter wet patches.

  • Protect yourself against mosquitoes in the spring and summer months. 
  • Hip boots or waders are a good idea in the spring and early summer months. 
  • Bring your binoculars and field guides, there's a lot to see! 
  • Please stay on the trail. This is an area of sensitive plants and deep springholes. 
  • "Be Bear Aware". Please don’t hike the preserve from mid-April to  mid-June when bears are most active and avoid hiking alone from spring until late fall.


Please report any bear activity (sightings, tracks, scat) to the U.S. Forest Service, Swan Lake District at (406) 837-5081.

Getting to the Preserve

The Swan River Oxbow Preserve is located 2.5 miles south of Swan Lake. From Highway 83 go west on Porcupine Road for 1/4 mile. A road on the right with a directional sign will lead you to a parking area and kiosk at the trail head.


Have you been to this preserve? Are you thinking of visiting? See what others are saying about their experiences and add your comments below.

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