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Show PART III CURRENT WATERSHED CONDITIONS AND PROBLEMS, AND EFFECTS OF PROBLEMS Water erosion damage on privately owned rangeland is mainly by rilling and gullying. Much of the accelerated erosion is caused by overgrazing and concentration of runoff along stock trails and roads. Silty and clayey soils in the dry foothills and valleys at elevations below 7,000 feet are particularly susceptible due to their physical characteristics and the sparser cover. Some of these soils are sodium affected and salty or gypsiferous. Gullies are frequent in the associ- ated deep alluvial soils bordering drainageways. Soil piping is often a contributing cause to the enlargement of gullied lands. Wind erosion damage on rangeland is essentially restricted to those soils with sandy loam and loamy sand surface layers that lack protective cover. Damage is severe locally in terms of soil removal and damage to grass where the windblown material is deposited. Areas affected by severe wind erosion are mostly at elevations below 7,000 feet where annual precipitation is low. These sandy soils susceptible to wind removal often occupy the exposed crests of slopes and ridges as well as smooth, nearly level tracts. Indian Land The pattern of range use on many Indian lands has resulted in serious deterioration of vegetal cover and accelerated erosion by wind and water. Control of livestock, reseeding and vegetal manipulation have stabilized the soil and substantially reduced sediment yields in some areas. Active head cutting and entrenching of valleys has destroyed appreciable land acreage and effectively dewatered adjacent rangeland. The effects of streambank and streambed erosion on the dry intermittent reservation streams is readily evident throughout the region. Within the lifetime of those using the land, streams that had been diverted to the adjacent fields with a shovel now require permanent diversion structures of major design. National Forest Land NationaL forest watershed conditions are improving on the whole, however, there are still some 332,600 acres requiring treatment for sheet erosion. There are still a few overstocked ranges but the stocking rates for livestock are being brought in line with the range carrying capacity. As the remaining allotments are put under intensive managemait this source of watershed damage will be controlled. There are 27,500 acres of unstable areas resulting from road and trail, mining, and miscellaneous other disturbed areas described below. Accelerated erosion may be caused on and below bare slopes created by road and trail construction. This problem is most serious along roads in the mountains, although it may be found in some degree wherever roads are built. Trail erosion is not usually as serious as road erosion, since smaller quantities of earth are moved in trail construction and smaller surfaces are laid bare. 28 |