2019-11-22_REVISION - C1981019 (2)

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RULE 4 PERFORMANCE STANDARDS 4.15.5 Grazing All the lands reclaimed by Colowyo will not be grazed by livestock for a period of at least three years after seeding or planting and will be managed to promote the postmining land use. Grazing by livestock will not commence until Colowyo has demonstrated to the satisfaction of the Division that the vegetation on the reclaimed surface is adequately established and can be expected to withstand grazing pressures. Any grazing studies undertaken by Colowyo will not preclude or interfere with postmining vegetation sampling as required in section 4.15.8. 4.15.6 Field Trials In 1975 Colowyo funded a revegetation study that was initiated on the Colowyo property by the Department of Agronomy at the Colorado State University and the Colorado State University Experiment Station. The study was designed and the work was monitored mostly to determine the suitability of using native species at the mine site. Test plots were used to simulate the disturbance that would result from surface mining. The complete details of the four-year revegetation study are found in Exhibit 10, Vegetation Information. Also, in 1977 an additional shrub study was initiated in conjunction with the Soil Conservation Service, Upper Colorado Environmental Plant Center. Approximately 35 species of shrub seedlings from the Plant Materials Center were being evaluated for potential use in mined land revegetation. Field trials have been, and continue to be, an ongoing effort at Colowyo since these initial studies indicated above (1975 and 1977). The most recent evaluation of efforts to establish shrubs and trees in pre-2000 revegetation resulted in the following assessment by Cedar Creek Associates, Inc. (2006): "Given the assumptions presented,past and present shrub counts, as well as recent shrub mapping, it can be postulated that the planting of bare root shrubs and containerized trees from 1979 through 2000 can be considered a failure (<10%survival). Shrub populations or patches on an overwhelming majority of reclaimed surfaces [prior to 2000] are well below the [old] success standard of 1,000 woody plants per acre (except within fenced enclosures) and a majority of the surviving shrubs in open (unfenced) revegetation were not planted,but were apparently included in the seed mix (i.e. Big Sagebrush-Artemisia tridentata). There is no doubt that browsing by big game species, as well as competition from aggressive grass species such as smooth brome (Bromus inermis) and intermediate wheatgrass (Agropyron intermedium)have prevented germination and growth of shrub populations on pre-2000 revegetation. Therefore, future bare-root planting of shrubs on new and older reclamation is not recommended based on very poor perfbrmance in thu past. :Miy effort to increase stirab densities on utder Rule 4 Performance Standards 4-50 Revision Date: 11/18/19 Revision No.: MR-211