Big Hole River

Freestone country. Salmonflies. The last fluvial grayling in the lower 48.

The Big Hole is the long, looping freestone that drains the wide valley between the Pioneer and Pintler ranges in southwest Montana. It runs roughly 155 miles from its source above Jackson, MT down to its confluence with the Beaverhead near Twin Bridges, where the two together form the Jefferson.

It is the river fluvial Arctic grayling never left. Once native to several upper Missouri tributaries, river-dwelling grayling now persist as a self-sustaining population only here, in the upper Big Hole — a fact that has shaped four decades of conservation work and a Candidate Conservation Agreement with Assurances signed by hundreds of valley landowners.