Eastern and Southern Idaho BLM Classification

Welcome to the web site for the Classification and Management of USDI Bureau of Land Management's Riparian and Wetland Sites in Eastern and Southern Idaho (2002) by Paul L. Hansen and James B. Hall

The work began in 1992 on lands administered by the Upper Snake River District Office of the USDI Bureau of Land Management (the former Idaho Falls, Shoshone and Burley Districts) in southeastern and south central Idaho. It is bounded by the Continental Divide at the Idaho/ Montana border to the north, and the Idaho/Wyoming border along the Teton Range, Snake River Mountains, and Salt River Range to the east. The boundaries to the south and west are less obvious, physiographically. To the south, it is delineated by the Idaho/Utah and Idaho/Nevada borders which run along an east/west axis bisecting a series of parallel, block-faulting ranges aligned north/south. The western boundary, just to the west of Twin Falls and U. S. Highway 93, courses north from the Nevada border near Idavada. It overlaps the Salmon Falls Creek Canyon to its intersection with the Snake River Canyon, then continues northwest along the Snake River Canyon to an area just west of King Hill. The boundary then angles north, following the Elmore/Camas county line, and turns east at the northeast corner of Elmore county, where it parallels the southern boundary of Custer County, progressing essentially southeast toward the Craters of the Moon National Monument. It then bends northeast, along a sinuous route along the Custer and then Lemhi county lines, where it converges with the Continental Divide approximately 40 km (25 mi) west of Monida Pass on the Idaho/Montana border.

The study area is divided among three distinctly different geologic regions: the Idaho Batholith occupies the northwestern corner in central Idaho, the Basin and Range characterizes the southeastern corner along the Utah and Wyoming borders, while the Snake River Plain composes a wide swath angling from the south central part of the state up to the northeast corner near Yellowstone National Park. The Idaho Batholith is a granitic formation, the result of colliding lithospheric plates and the upwelling of hot magma. The Basin and Range Region is a product of two superimposed mountain ranges and the forces, which led to their creation and subsequent deformation. The Snake River Plain is primarily the result of volcanic activity that started some 13 million years ago. Glaciation during two separate ice ages, although responsible for scouring much of the landscape to the north in Montana and northern Idaho, and along the higher ranges to the east and south in Wyoming and Utah, did not play a significant role in the development of the topography in this area.

A total of 61 types, from approximately 1,420 plots, are described in this classification:

8 coniferous tree-dominated habitat types (7) and community type (1);
14 deciduous tree-dominated habitat types (3) and community types (11);
12 willow shrub-dominated habitat types (6) and community types (6);
9 non-willow shrub-dominated community types;
4 sedge herbaceous-dominated habitat types (3) and community types (1); and
14 non-sedge herbaceous-dominated habitat types (7) and community types (7).