The Cassia Division and adjacent public lands cover a large geographical area. This area includes the southwestern portion of Cassia County, and the southeastern portion of Twin Falls County. The majority of this area is included in the Cassia Division of Sawtooth National Forest. The city of Twin Falls, Idaho is to the north, along with the smaller towns of Hansen, Kimberly, and Murtaugh. The Oakley Reservoir, the town of Oakley, and Goose Creek are on the east. Rogerson, Salmon Falls Dam, and the Shoshone Basin area are to the west. The south boundary of the forest and adjacent public lands is the Idaho/Nevada border. The general region used for this survey includes BLM, National Forest, and state lands. See Figures:

• M-1
• M-2
• M-3
• M-4
• M-5

There is a small amount of private land located within the national forest and the BLM areas. Extensive private land adjoins the Cassia Division on the west side.

The Cassia Mountains and adjacent lands are on the edge of the Western Basin and Range ecosystem subregion. The area borders the Owyhee Uplands Section and the Snake River Basalts Section (Ecoregions of the United Sates, USDA Forest Service, 1994). The area is referred to locally as the "South Hills". Mountains range from 4,500 feet to over 8,000 feet. Monument Peak is the highest point, rising to 8,060 feet.

The Cassia Mountains are a broad uplift of Paleozoic sediments and Cenozoic volcanic rock that lies mainly in Idaho but also extends into Elko County, Nevada. The north edge of the range adjoins the Snake River Plain. Many of the mountain ridges are capped by welded volcanic tuffs over softer ash beds. A large number of drainages dissect the region (Geological Reconnaissance of the Cassia Mountain Region, Youngquist and Haegle, 1956).

The climate of the Cassia Division and adjacent lands is arid to semi-arid with wide temperature variations. Winters may see lows of -16 ⁰F or less, and summer highs may range over 100 ⁰F during the day yet drop to as low as 50 ⁰F at night. A majority of the region receives less than 12 inches of annual precipitation. Exceptions are small areas of higher elevation and isolated accumulation points (Geology and Water Resources of the Goose Creek Basin, Piper, 1923). One of these localized points of higher accumulation is upper Rock Creek, which includes the Magic Mountain Ski Area. A paved access road is maintained to this area. Other roads and higher locations are generally inaccessible from the end of November through the beginning of June.

The recreational values and uses of the Cassia Division and adjacent lands are high. The region 5 recreational uses include camping, hiking, hunting, fishing, mountain biking, prospecting, off-road vehicle recreation, and winter sports. The main road from Twin Falls to the ski area is paved and well maintained. Good access for most vehicles (in dry weather) can be obtained from Rogerson, Idaho on the west. The roads from Oakley to the Rock Creek area are not well maintained, but can accommodate most vehicle types when dry. See Figure M-6.

Many improved visitor sites are maintained within the Sawtooth National Forest. There are campgrounds, group camping sites, and trails. Points of interest include Ross Falls, Phantom Falls and Shoshone Wildlife Ponds. The Big Cottonwood Wildlife Management Area is adjacent to the forest on the east side and provides visitors an opportunity to view wild turkeys and other wildlife. The Oakley Reservoir, also on the east side, is privately owned but available for public use. Although the facilities are unimproved, the site is very popular for boating, fishing, and other water sports. The BLM lands immediately adjoining the Cassia Division have no improved visitor facilities at this time. Area streams and the Oakley Reservoir are stocked by the Idaho Department of Fish and Game to improve fishing opportunities.

The Cassia Division and adjacent lands support a wide variety of plant communities. Sagebrush-steppe and shrub-steppe communities occupy much of the lower foothills as well as valleys and hillsides at higher elevations. Native forbs (herbaceous plants) and grasses as well as many introduced species are found throughout the shrub-steppe regions as well as within other plant communities. Sagebrush communities include both Big Sagebrush and Low Sagebrush species (Sagebrush-Grass Types of Southern Idaho, Hironaka et al, 1983).

Bitterbrush communities are common among upper rocky outcrops and along mesa edges. Utah Juniper and Rocky Mountain Juniper are a common community type in much of the region. Interior zones, north slopes, and higher drainages include groves of Aspen, Lodgepole Pine, Sub-alpine Fir, and other species. Some of the upper areas also support Mountain Mahogany communities (Geological Reconnaissance of the Cassia Mountains, Youngquist and Haegele, 1956). Riparian locations host Willow, Elderberry, and other riparian shrub species.

Rare plant values include the presence and potential for additional populations of Idaho Penstemon (Penstemon idahoensis) and Goose Creek Milkvetch (Astragalus anserinus) in the southeastern portion of the range. The exposed volcanic ash soils found in these areas are the soil type that hosts Idaho Penstemon. Known populations of these plants are located within the Goose Creek watershed, with several known locations on the Cassia Division (CDC Database, Idaho Department of Fish and Game, 1999). Other rare plant values of the Cassia Division and adjacent areas include the Simpson's Hedgehog Cactus (Pediocactus simpsonii). Additional rare plant inventories have yet to be conducted in this region (Idaho Rare Plant Conference, Cheney, 2000).

Native vegetation has been altered in some of the region through past activities including prescribed burns and Crested Wheat-grass seedings. Rangelands at lower elevations, particularly in areas of controlled or natural burns, have been heavily invaded by Cheat Grass (Bromus tectoum). The Trapper Creek Research Natural Area, established by the Forest Service for its native plant values, has been disturbed by both fire and livestock and is also being invaded by Cheat Grass. Cheat Grass competes with perennial native grasses, and is common on overgrazed or disturbed rangelands (Weeds of the West, Whitson et al, 1999).

Watershed values of the Cassia and adjacent public lands are very high. More existing and historic spring and stream sites exist within this division than any of the other southeastern areas covered in this survey. Despite limited precipitation over much of the region, the Cassia Division and adjacent lands produce a lot of surface flow in the form of creeks and springs. Many additional drainages contain ephemeral and intermittent streams that run during wet years or after heavy precipitation events. A large number of streams are generally perennial and sustain a wide range of riparian and wildlife values. Remnant riparian vegetation in many drainages and at a large number of dry spring sites indicates that even more surface water may have been available in the past.

Aspen groves are a very valuable watershed component (Aspen Community Types of the Intermountain Region, Mueggler, 1988) and are prominent features in much of the higher and interior areas of the Cassia Division. Wells have been drilled at some lower elevations to provide water sources for livestock. Many historic springs visited in the region during this survey have been developed for livestock use and no longer provide surface water at their original sites.

Fisheries values and potentials of the Cassia Division and adjacent public lands are very high. The waters of Trapper Creek contain the sensitive fish species Leatherside Chub. The waters of Goose Creek, Trapper Creek and other streams are historic Yellowstone Cutthroat Trout habitat. Remnant populations of Red-band Trout have been found within the Cassia Division. There are also unconfirmed reports of remnant Bull Trout on the Cassia Division (Idaho Department of Fish and Game, 2000). Rainbow, Brook Trout, and other species also inhabit the regions waters.

The Cassia Division and adjacent lands support Mule Deer, Elk, and many other mammals. Snowshoe Hares are present in several locations. The Cassia Division and adjacent lands have the potential for remnant lynx populations. Potential lynx foraging and denning habitat exists throughout the region. Lynx were found in the Magic Valley area and the "South Hills" (south of Hansen) as recently as 1972 (Idaho's Canada Lynx:

Pieces of the Puzzle, Lewis, 1998). The Cassia Division still had documented native wolf populations in 1923 (Geology and Water Resources of the Goose Creek Basin, Piper, 1923). Suitable habitat still exists for wolves in the region. Recent sightings of wolves on the Cassia Division have been reported by a number of individuals, but have not been confirmed yet by the US Fish and Wildlife Service.

State sensitive species on the Cassia Division and adjacent lands include Pygmy Rabbits and Cliff Chipmunks (CDC Database, Idaho Department of Fish and Game, 1999). The Cliff Chipmunk is known in Idaho exclusively from Cassia County (Atlas of Idaho's Wildlife, Idaho Department of Fish and Game, 1997). The many rocky canyons and cliffs are important bat roosting sites and many locations are being actively used by a variety of species, including Pallid Bats (CDC Database, Idaho Department of Fish and Game, 1999). Idaho Department of Fish and Game maintains the Big Cottonwood Wildlife Management Area northeast of Oakley. This site has been used to establish transplanted populations of Big-horned Sheep and Wild Turkeys.

The Cassia Division and adjacent public lands provide foraging and nesting habitat for

Idaho state sensitive raptor species including the Northern Goshawk, Ferruginous Hawk, Boreal Owl, Flammulated Owl, and Northern Pygmy Owl. Peregrine Falcons have had confirmed nest sites within this region in the past. (CDC Database, Idaho Department of Fish and Game, 1998).

Western Burrowing Owls, also a state sensitive species, are successfully nesting at lower elevations of the range and along the foothills that extend out into the valleys. Other Idaho state sensitive bird species in the region include the Loggerhead Shrike, Least Goldfinch, Lark Bunting, Pinyon Jay, Bobolink, White-faced Ibis, Long-billed Curlew, Common Loon, and many others (CDC Database, Idaho Department of Fish and Game, 1999). Rocky cliffs and canyons such as Rock Creek are suitable habitat for the WhiteThroated Swift.

Sage Grouse are still present in much of the Cassia Division and adjacent lands, but in numbers far below their historic levels (Geology and Water Resources of the Goose Creek Basin, Piper, 1923). The riparian zones of the western portion of the Cassia Division as well as adjacent areas are historic Mountain Quail habitat. Mountain Quail have been extirpated from almost all of their historical habitats, including this area (Petition for Rules to List Mountain Quail, Kavanaugh et al, 2000). Many other species of birds also rely on the habitats provided by the region, including the Vesper and Brewer's Sparrow, both sagebrush obligates (Atlas of Idaho's Wildlife, Idaho Department of Fish and Game, 1997).

The Cassia Division and adjacent public lands provide habitat for a number of Idaho's reptile and amphibian species. Amphibians, both frogs and toads, are present at riparian and aquatic sites. The BLM feels that the some of the areas may still host the state's less common amphibians such as the Spotted Frog. The region hosts Idaho reptiles such as the Rubber Boa and Striped Whipsnake. There are suitable locations that may have been historical habitat for the uncommon or rare Longnose Snake (Rhinocheilus lecontei) as well as possible historical habitat for the Ringneck Snake (Idaho's Amphibians and Reptiles, Idaho Department of Fish and Game, 1994). Unconfirmed reports of Longnose Snakes exist for the Goose Creek area, south of the Cold Creek confluence.

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 Cassia Division and on adjacent lands. 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.

The Cassia Division and adjacent public lands are 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 in the Cassia Division and on adjacent lands in order to determine the condition of riparian habitats following the 1999 grazing season.

Due to the large geographical area involved, the number of sites in this presentation has been limited to 39 representative locations. Many additional sites were visited and documented. The additional documentation will be kept on file with Idaho Watersheds Project. Sites on file reflect the same types of riparian conditions as those in the summary. The included sites come from various geographical locations around the Cassia Division and adjacent lands in order to offer the most widespread representation through limited publication space.

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.