Laserfiche WebLink
<br />, <br /> <br />t,; IV. CONTROL OF SALINITY IN SURFACE RUNOFF <br />o <br />~ Salinity in surface runoff is believed to be directly related to content <br />and availability of salt in soils and movement of soils by erosion. <br />Therefore, salinity should be reduced through any activity which leads <br />to increased infiltration and reduced or controlled runoff. The major <br />causes of soil di sturbance and sa 1 i nity on pub 1 i c 1 ands are grazi ng by <br />domestic livestock, feral horses and burros, and wildlife; recreation <br />activities, including off-road vehicles (ORV); oil-gas and mineral <br />exploration; mining claim assessment work; and development activities <br />and final production of oil-gas wells, underground mines, and surface <br />mining of coal resources. <br /> <br />~ <br /> <br />, <br /> <br />A. Oil-Gas Activities, Mining, and ORV <br /> <br />~"';.; <br /> <br />Control of salinity requires that uses by man be allowed only to the <br />degree that they do not result in loss of soil.. In the case of surfac.e <br />mining, where the soil and vegetation are completely destroyed.and' <br />highly saline or other toxic minerals are brought from great depths to <br />the surface, mitigating measures will be needed. These should include <br />retention dams to collect and hold toxic runoff, proper design of sup- <br />port facil ities, such as access or haul roads, and restoration of top- <br />soil and vegetation to the site when mining operations are completed. <br />When ORV use is allowed on saline, fragile soils, it should be recog- <br />nized that it may cause irreversible harm to soils and vegetation. <br />Control of salinity can be accomplished by confining ORV use to pres- <br />cribed areas where runoff and sediment can be retained in reservoirs. <br /> <br />B. Grazing Management <br /> <br />For purposes of this report, the following definitions are used for <br />grazing intensities: liah~, 21-40 percent utilization; moderate, 41-60 <br />percent utilization; an eavy, 61-80 percent utilization of the usable <br />vegetation; see BLM Manual on Range Studies (1). <br /> <br />Effects of extens ive use, such as 1 i vestock grazi ng, on sa 1 i nity can be <br />reduced through proper application of accepted grazing management <br />principles. These include the allowance of grazing when soils and <br />plants are least harmed by trampling or defoliation (proper season of <br />use), control of livestock numbers to reduce harmful impacts, rotation <br />of grazing and rest treatments to increase vegetative cover, and total <br />exclusion of grazing where necessary. Key elements to be considered <br />when prescribing grazing treatments are soil and vegetation factors as <br />they relate to reduction of salt concentration in surface runoff. <br />Treatments pres.cribed may be different from those designed when max- <br />imization of livestock benefits is appropriate. <br /> <br />BLM (3) described general characteristics of grazing treatments .that <br />could be prescribed for three classes of saline lands, i.e., nonsaline- <br />slightly saline, moderately saline, and highly saline. No changes are <br />suggested for treatments appl ied to. nonsal ine-sl ightly sal ine and mod- <br />erately saline lands, <br /> <br />7 <br /> <br />'- <br /> <br /><'_.;c ,', .,'^ -_-""-~"'.1.*- <br /> <br /> <br />'" <br />.'~ <br /> <br />" <br /> <br /> <br />t' <br /> <br />,-, i.1<i.-__t-_n-"~~AE_>; ,~~ <br /> <br />