Physical and Human Geography of Henry's Fork Watershed

Abstract

The 8444-km2 Henry's Fork watershed lies in eastern Idaho and western Wyoming. It is bounded by the Continental Divide to the north, the Yellowstone Plateau and Teton Range to the east, the Big Hole Mountains to the south, and the Snake River Plain to the west. The Upper Henry's, Lower Henry's and Teton hydrologic units comprise the watershed, whose major streams are the Henry's (North) Fork of the Snake, Teton and Fall rivers. Recently fanned volcanic features, including the Snake River Plain, Island Park Caldera, and Madison and Pitchstone plateaus, dominate the geology. Mean annual temperature and precipitation, respectively, range from about 5.3 ° C and 30 cm at the lowest elevations (1400 m) to less than 1 ° C and over 100 cm at the highest elevations (3300 m). Pine, fir and spruce forests dominate upland areas; sagebrush steppe and cultivated agricultural land are found at lower elevations. Native people used the area seasonally for fishing, hunting and gathering. The area was first settled by Euro-Americans in the mid- to late 19'h century and remains sparsely populated. The watershed boundary roughly coincides with that encompassing the Idaho counties of Fremont, Madison and Teton, where jobs are provided primarily by agriculture and other natural-resource-related occupations, construction, service industries and government. About 50 percent of the watershed is federally owned, and forest, range and agriculture account for about 95 percent of land use. The watershed is well known for seed potato production and outstanding outdoor recreational opportunities, most notably fishing, snowmobiling, and skiing.