The Idaho portion of Shoshone Basin extends northwards from the Idaho/Nevada border. The Cassia Division of Sawtooth National Forest is on the east side; Highway 93 between Twin Falls, Idaho and Jackpot, Nevada is to the west. The town of Rogerson and the Salmon Falls Dam area is also to the west, the city of Twin Falls is located approximately 25 miles to the north. Much of the northern Shoshone Basin area is private land with isolated small areas of state and BLM land. A more consolidated area of BLM land with scattered state land sections forms the southern portion of what the map identifies as Shoshone Basin. See Figure M-1. Extensive areas of private land are between the BLM lands and the Cassia Division on the east side.
8.1 Physical Environment
The Shoshone Basin area and adjacent lands are on the edge of the Western Basin and Range ecosystem subregion; this area includes portions of the Owyhee Uplands Section and the Snake River Basalts Section (Ecoregions of the United Sates, USDA Forest Service, 1994). Elevations range from less than 4,500 feet to over 6,000 feet. The east edge of the Shoshone Basin includes faulted limestones and quartzites, with hot springs along some of the faults. Most of the region is soft volcanic ash with scattered lava flow cappings (Roadside Geology of Idaho, Alt and Hyndman, 1991).
Summers are generally quite dry. Average annual precipitation for the Shoshone Basin and adjacent lands is less than 12 inches per year (Geology and Mineral Resources of Eastern Cassia County, Anderson, 1931). Average annual temperatures range from daytime highs of 40 0F or less in January to 90 0F or more in July. General access is limited to improved gravel roads from the north and west, as well as a back-country road from Jackpot, Nevada. Travel becomes difficult once the roads are wet, and arc not well maintained during winter months.
8.2 Recreational Values
The recreational values and uses of the Shoshone Basin are limited mainly to hunting, some fishing, prospecting, and other related outdoor activities. Good access for most vehicles (in dry weather) can be obtained from Rogerson or Twin Falls; the back road from Jackpot is not as well maintained. Some access to the National Forest on the east is also available, although limited by areas of private land.
8.3 Vegetation Values
The Shoshone Basin and adjacent lands mainly support Sagebrush-steppe and shrub-steppe communities. Sagebrush communities include both Big Sagebrush and Low Sagebrush species (Sagebrush-Grass Types of Southern Idaho, Hironaka et al, 1983). Streams and springs support limited riparian communities in some locations, but most have been heavily impacted in the past. Isolated wet meadows and signs of more extensive historic meadows exist at some spring sites. Scattered junipers and juniper communities are present in some locations.
Rare plant values include the presence or potential for populations of Taper-tip Onion (Allium anceps), Owyhee Mourning Milkvetch (Astragalus atratus var. owyheenisis), Four-wing Milkvetch (Astragalus tetrapterus), White-margined Wax Plant (Glyptopleura marginata), Stemless Townsendia (Townsendia scapigera), Torrey's Blazing Star (Mentzelia torreyi var. acerosa), Simpson's Hedgehog Cactus (Pediocactus simpsonii), Dwarf Skullcap (Scutellaria nana), and Davis Peppergrass (Lepidium davisii).
The Owyhee Mourning Milkvetch can be found near Magic Hot Springs on the canyonsides of Shoshone Creek. Davis Peppergrass has been a Federal Category II species and is recommended for Threatened status. Major threats in the Shoshone Basin area to these species include water storage pond development, spring livestock trampling, overgrazing, range improvements, range fires, rehabilitation projects, and off-road vehicles (Sensitive Plants of Burley BLM District, DeBolt, 1989).
Native vegetation has been altered in many areas of the Shoshone Basin region through past activities including fires and Crested Wheat-grass seedings. Rangelands have been invaded by Cheat Grass (Bromus tectoum) and other exotic annuals such as Burr Buttercup (Ranunculus testiculatus). Cheat Grass and other exotics compete with native grasses and forbs (herbaceous plants), and are common on overgrazed or disturbed rangelands (Weeds of the West, Whitson et al, 1999).
8.4 Watershed and Wildlife Values
Watershed values of the Shoshone Basin region and adjacent public lands are limited by precipitation amounts. Despite limited precipitation, the region still provides surface flow in the form of creeks and springs. Many small drainages contain ephemeral streams that flow during snow-melt or after heavy precipitation events. Other stream and spring flows are intermittent over much of their course. A few streams are perennial and provide more substantial riparian and wildlife values.
Remnant riparian vegetation in some drainages and at dry spring sites indicates that even more surface water may have been available in the past. Wells have been drilled at some locations to provide water sources for livestock. Historic springs in the region have been developed for livestock use and some of these no longer provide surface water at their original sites.
The Shoshone Basin and adjacent lands support a wide variety of both game and non-game wildlife species. The waters of Shoshone Basin support remnant Red-Band/Rainbow Trout populations; although it has not yet been determined if they are native to the basin itself (Idaho Department of Fish and Game, 2000).
The Shoshone Basin supports Antelope, Mule Deer, Bobcats, Badgers, and other mammals. The rocky canyons and cap-rock cliffs are important bat roosting sites. The region provides foraging and nesting habitat for raptors including the Short-eared Owl, Prairie Falcon, Golden Eagle, Northern Harrier, and Ferruginous Hawk. The Ferruginous Hawk is a state sensitive species (CDC Database, Idaho Department of Fish and Game, 1998). Other Idaho state sensitive bird species in the region include the Loggerhead Shrike (CDC Database, Idaho Department of Fish and Game, 1999). Rocky cliffs and canyons, such as Shoshone Creek Canyon are suitable habitat for the White Throated Swift.
Many other species of birds also rely on the habitats provided by the Shoshone Basin, including the Vesper Sparrow, Brewer's Sparrow, and Sage Grouse; all sagebrush obligates (Atlas of Idaho's Wildlife, Idaho Department of Fish and Game, 1997). Sage Grouse have active lek sites within the region (Idaho Department of Fish and Game, 2000).
Shoshone Basin provides habitat for a number of Idaho's reptile and amphibian species. These include the Striped Whipsnake, Rubber Boa, and Racer. Shoshone Basin contains suitable locations that may have been historical habitat for the uncommon or rare Longnose Snake, Rhinocheilus lecontei (Idaho's Amphibians and Reptiles, Idaho Department of Fish and Game, 1994).
Terrestrial Gastropods (snails) are present at riparian sites in Shoshone Basin. Most snail populations are endemic and constitute separate species from those in other geographical locations. Snails are very sensitive to changes in their environment. Due to their limited environment and incapacity for migration, snails are subject to extirpation from disturbances such as livestock grazing, trampling, and water developments (Oregon Natural Desert Conference, Freist, 2000).
Habitat conditions have profound short and long-term effects on which species are able to successfully use a location. Mammal and bird observations were recorded during the surveys performed at a variety of riparian locations in the Shoshone Basin. This data is included in Appendix F for the benefit of interested land managers or members of the public. The presence or non-presence of species, presence of habitat-generalists, and other clues provided by the frequency observations can aid in determining the health of a riparian system or identifying needed changes. Although short-term data is not definitive for these locations, it is indicative and has been made available as a management resource.
8.5 Riparian Conditions
The Shoshone Basin area is currently being used for livestock grazing purposes. Livestock utilization of riparian habitat can lead to adverse impacts of vegetation, watershed, and wildlife values if proper guidelines and standards are not applied. A survey has been performed of representative seeps, springs, and riparian zones within the Shoshone Basin area to determine the condition of riparian habitats following the 1999 grazing season.
Each of the following summaries contains a short description of impacts, recommendations for action, and photographic documentation. The recommendations reflect current (year 2000) riparian recovery times recommended by the USDA Forest Service Intermountain Region and Rocky Mountain Research Station scientists.
The following sites have been summarized in this chapter:
1. Bull Spring
2. Deep Creek (North Fork Junction)
3. North Fork
4. Rattlesnake Spring
5. Rock Cabin Spring, Unnamed Springs to South
6. Shoshone Creek Locations, Springs
7. Unnamed Spring, BLM
8. Unnamed Spring, State Meadow
9. Unnamed Spring, State "Ponds"
10. Unnamed Springs, BLM Wet Meadow
11. Winter Spring