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<br />w <br />c.n <br />w <br />~ <br /> <br />A. Salt From Surface Runoff <br /> <br /> <br />IX. SUMMARY <br /> <br />A number of activities, including livestock grazing, off-road vehicle use~ <br />oil and gas activity, mining claim exploration and development, and coal <br />mining activity, can be contributing factors to salt in surface runoff <br />from public lands. Each of these factors must be dealt with on a si~e- <br />specific basis to determine the extent of salt contribution and to plan <br />measures necessary to reduce the concentration to acceptable levels. <br /> <br />, <br /> <br />Improper livestock grazing can have a significant influence on the amount <br />of sediment and salt yielded in surface runoff from rangelands. The im- <br />portance of controlling the period and intensity of grazing, the kind of <br />animal, and the need for rest from grazing to improve range condition is <br />stressed. Light to moderate grazing during the season when plants or <br />soil s are least 1 ike1y to be damaged, periodic rest from grazing through <br />the use of grazing management systems, and total removal of livestock from <br />areas with unstable soils or little potential to support a protective cover <br />of vegetation are specific ways livestock can be managed to reduce salinity. <br /> <br />Salinity control through grazing management will vary with the concen- <br />tration of salts in the soil. Specific management which may be employed for <br />each type is as follows: <br /> <br />1. Nonsa1ine - Slightly Saline Lands <br /> <br />Grazing management to meet salinity objectives should strive to produce a <br />maximum volume of runoff while at the same time maintaining a stable soil <br />with a minimum loss of sediment through erosion. This loss of water to <br />the soil-water reservoir will reduce forage production for livestock and <br />wildlife below its natural potential. However, the higher quality water <br />(usually below 300 mg/1 salt concentration) will dilute the more saline <br />waters in the Colorado River system and at Imperial Dam, California, and <br />thus reduce salinity. <br /> <br /> <br />- <br /> <br />" <br /> <br />2. Moderately Saline Lands <br /> <br />Grazing of livestock at a light to moderate level, in accordance with a <br />schedule of use and rest treatments designed to provide maximum protec- <br />tion for soil and plants, will reduce salinity in surface runoff. . The <br />Objective on these lands is to increase infiltration and reduce runoff <br />and loss of saline sediment. Salt concentration in runoff water exceeds <br />that measured in receiving streams. <br /> <br />3. Highly Saline Lands <br /> <br />Moderate grazing in winter when soils are frozen may not significantly <br />increase salinity on areas where forage production is sufficient to <br />support grazing animals. Soil factors have a most important influence <br />on. infiltration and runoff on areas having a very sparse ground cover <br />of perennial vegetation. Plants have only a slight influence due to <br />their scarcity. <br /> <br />32 <br /> <br />