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RULE 4 PERFORMANCE STANDARDS <br /> gullies. The efficacy of these mechanical techniques will continue to be closely monitored as <br /> changes to the reclamation program are initiated. <br /> 4.15.5 Grazing <br /> All the lands reclaimed by Colowyo will not be grazed by livestock for a period of at least three <br /> years after seeding or planting and will be managed to promote the postmining land use. <br /> Grazing by livestock will not commence until Colowyo has demonstrated to the satisfaction of the <br /> Division that the vegetation on the reclaimed surface is adequately established and can be expected <br /> to withstand grazing pressures. Any grazing studies undertaken by Colowyo will not preclude or <br /> interfere with postmining vegetation sampling as required in section 4.15.8. <br /> 4.15.6 Field Trials <br /> In 1975 Colowyo funded a revegetation study that was initiated on the Colowyo property by the <br /> Department of Agronomy at the Colorado State University and the Colorado State University <br /> Experiment Station. The study was designed and the work was monitored mostly to determine the <br /> suitability of using native species at the mine site. Test plots were used to simulate the disturbance <br /> that would result from surface mining. <br /> The complete details of the four-year revegetation study are found in Exhibit 10, Vegetation <br /> Information. <br /> Also, in 1977 an additional shrub study was initiated in conjunction with the Soil Conservation <br /> Service, Upper Colorado Environmental Plant Center. Approximately 35 species of shrub <br /> seedlings from the Plant Materials Center were being evaluated for potential use in mined land <br /> revegetation. <br /> Field trials have been, and continue to be, an ongoing effort at Colowyo since these initial studies <br /> indicated above (1975 and 1977). The most recent evaluation of efforts to establish shrubs and <br /> trees in pre-2000 revegetation resulted in the following assessment by Cedar Creek Associates, <br /> Inc. (2006): <br /> "Given the assumptions presented,past and present shrub counts, as well as <br /> recent shrub mapping, it can be postulated that the planting of bare root <br /> shrubs and containerized trees from 1979 through 2000 can be considered a <br /> failure(<10% survival). Shrub populations or patches on an overwhelming <br /> majority of reclaimed surfaces [prior to 2000] are well below the [old] <br /> success standard of 1,000 woody plants per acre (except within fenced <br /> enclosures) and a majority of the surviving shrubs in open (unfenced) <br /> revegetation were not planted,but were apparently included in the seed mix <br /> (i.e. Big Sagebrush-Artemisia tridentata). There is no doubt that browsing <br /> by big game species, as well as competition from aggressive grass species <br /> such as smooth brome (Bromus inermis) and intermediate wheatgrass <br /> (Agropyron intermedium)have prevented germination and growth of shrub <br /> Rule 4 Performance Standards 4-50 Revision Date: 1/22/20 <br /> Revision No.: TR-136 <br />