On August 22, 1805, Lewis and Clark first noted Arctic grayling in the Beaverhead River south of present day Dillon, Montana. At the time, Arctic grayling occurred in the Missouri River drainage upstream of present Great Falls, Montana. Sadly, by 1950, the Big Hole River contained the last remaining population of fluvial (river dwelling) Arctic grayling in the lower 48 states (4% of former Montana range). Reasons for decline within the Missouri River system include: habitat degradation, over fishing, drought, and competition from non-native fish. Fluvial Arctic grayling tend to live in river systems where large annual migrations can occur. Fur trappers in the early 1800's told of a Big Hole Valley with thousands of acres covered with riparian shrubs and beaver dams.

This large scrub-shrub riparian area has changed considerable over the last century, but it is still home to such species as Canada lynx, wolverine, river otter, northern goshawk, westslope cutthroat trout, gray wolf, peregrine falcon, bald eagle, and Ute-Ladies’ tresses.