|
• SOIL SURVEY •
<br />surface or below the dark-colored surface layer. A few
<br />small azeae of soils that have bedrock at a depth of less
<br />than 40 inches or that have weak subsoil development are
<br />also included. Small areas where 1- to 2-inch peat layers
<br />are on the surface and the subsoil is mottled as a result
<br />of continuous irrigation are included.
<br />Typically, the surface layer is grayish brown loam
<br />about 14 inches thick. The subsoil is light olive brown clay
<br />about 25 inches thick. The substratum is light brownish
<br />gray clay, and it overlies shale bedrock at a depth of
<br />about 45 inches.
<br />Permeability is slow, and the available water capacity is
<br />high. Surface runoff is medium. The hazard of wind ero-
<br />sion is slight, and the hazard of water erosion is high.
<br />Most of the acreage is rangeland, but some areas are
<br />used as irrigated hayland and for recreation and wildlife.
<br />A cold climate and a short growing season limit the
<br />production of introduced grasses and preclude the use oY
<br />this soil as cropland.
<br />Management of this soil for range includes the use of a
<br />deferred grazing system and limited brvsh control Where
<br />this soil is irrigated, ditches and fields need to be care-
<br />fully designed to control irrigation water. Grasses recom-
<br />mended for seeding include western wheatgrass, slender
<br />wheatgrase, mountain brome, Arizona fescue, big
<br />bluegrass, and bluebunch wheatgraea. The dominant na-
<br />tive vegetation consists of western wheatgrass, slender
<br />wheatgrase, Junegrase, big sage, anowberry, and nu-
<br />merous forbs. The total annual production averages about
<br />1,600 pounds of air-dry forage per acre.
<br />Excessive elope and high shrink-swell potential are the
<br />moat limiting soil properties to be considered in the
<br />design of access roads and recreation homesite subdivi-
<br />sions. Snow removal becomes an increasingly greater
<br />problem as more homes are built. Slope stabilizaton is dif-
<br />ficult even where homes aze constrvcted on nearly level
<br />pads. Surface runoff resulting from snowmelt increases
<br />the erosion hazazd on cut and fill elopes. Seeding of
<br />vegetation minimizes the erosion hazard, but establishing
<br />a stand ie difficult. Homes should be designed to utilize
<br />existing elope and keep foundation cute to a minimum.
<br />Foundations should also be designed to withstand the
<br />shrinking and swelling of the clayey subso~7 and sub-
<br />stratum. Roads should be designed to keep cut and fill
<br />elopes to a minirnum and provide drainage outlets for ex-
<br />cessive snowmelt. All-weather asphalt surfaces aze im-
<br />practical unless provisions are made to offset frost and
<br />shrink-swell action.
<br />Rangeland wildlife on this soil includes deer, sage
<br />grouse, white-tailed jackrabbit, mourning dove, ground
<br />squirrels, and yellow-bellied marmot. Capability subclass
<br />V Ie.
<br />4-Cumulie Cryaquolls, nearly level. Cumulic
<br />Cryaquolls are on flood plains. They are poorly drained
<br />voila that are subject to annual flooding. Slope ie 0 to 6
<br />percent Cumulic Cryaquolls have a black surface layer 20
<br />or more inches thick and are underlain by sand and
<br />gravel at a depth of 2 to 4 feet Texture above those
<br />depths ranges from sandy loam to clay and is commonly
<br />stratified. The water table is within 12 to 24 inches of the
<br />surface sometime during the growing season. The availa-
<br />ble water capacity is low to high, and permeability is
<br />rapid to slow. Surface runoff is slow. The hazard of ero-
<br />sion by wind and water is slight.
<br />Included in mapping are small areas of soils like Cumu-
<br />lic Cryaquolls that have no dark colored surface layer or
<br />a thinner one. Also included are areas of Histic
<br />Cryaquolls.
<br />Most of the acreage is irrigated hayland, but same of it
<br />is used by wildlife. A cold climate and a short growing
<br />season limit the production of introduced grasses and
<br />preclude use of this soil as cropland.
<br />Management of Cumulic Cryaquolls requires proper use
<br />of irrigation water, subsurface drainage, and fertilization
<br />to maintain grass hay production. Grasses recommended
<br />for seeding are slender wheatgrass, mountain brome, reed
<br />canarygrase, and big bluegrass. The dominant native
<br />vegetation consists of tufted havgrass, slender wheat-
<br />grass, Nebraska sedge, reedgrass, willows, shrubby
<br />cinquefoil, and numerous forbs. The total annual produc-
<br />tion averages about 2,500 pounds of au•-dry forage per
<br />acre.
<br />These soils are used mainly for irrigated grass-hay
<br />production. Before the construction of Dillon and Green
<br />Mountain Reservoirs, irrigation was accomplished by the
<br />natural flooding from spring snowmelt. Now that the
<br />dams control the flooding, irrigation ditches must carry
<br />the water to the hayland. Irrigation systems should be
<br />designed to avoid over-irrigation and ponding and to
<br />return excess water to the river. Ponding of irrigation
<br />water results in decreased hay production.
<br />Spring fertilization is recommended because fall appli-
<br />cation can result in fertilizer being lost during spring
<br />snowmelt. Nitrogen and phosphate are recommended for
<br />moat irrigated hayland.
<br />Seasonal flooding and depth to water table are the
<br />most limiting soil properties to be considered in the
<br />design of access roads and recreation homeaite aubdivi-
<br />eione. The flooding hazard makes these soils unsuitable
<br />for such uses. They should be reserved for greenbelts,
<br />golf courses, and other restricted uses. Oneite investiga-
<br />tiane are needed before any construction is planned
<br />because there is a wide variation oP soil properties. Flood
<br />protection measures should be designed to control at least
<br />the storms of 1 in 100 year severity. Adequate soil
<br />drainage is needed for most land uses.
<br />Rangeland and wetland wildlife include deer, sage
<br />grouse, white-tailed jackrabbit, mourning dove, ducks,
<br />mink, and beaver. Capability subclass VIw.
<br />5E-Frisco-Peeler complex, 6 to 25 percent slopes.
<br />These are deep, well drained, moderately sloping to
<br />moderately steep soils on fans, mountainsides, and ridges
<br />in the south-central part of the survey area. They farmed
<br />in glacial drift derived from a variety of rocks. Elevation
<br />is 8,500 to 11,000 feet The average annual precipitation is
<br />about 21 inches, Lhe average annual air temperature is
<br />
|