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The use of these soil stabilizing practices on areas currently undergoing reclamation at <br />Colowyo has been very effective in controlling surface runoff, thereby preventing surface <br />erosion and gullies. The efficacy of these mechanical techniques will continue to be <br />closely monitored as 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 <br />least three years after seeding or planting and will be managed to promote the postmining <br />land use. <br />Grazing by livestock will not commence until Colowyo has demonstrated to the <br />satisfaction of the Division that the vegetation on the reclaimed surface is adequately <br />established and can be expected to withstand grazing pressures. Any grazing studies <br />undertaken by Colowyo will not preclude or interfere with postmining vegetation <br />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 <br />by the Department of Agronomy at the Colorado State University and the Colorado State <br />University Experiment Station. The study was designed and the work was monitored <br />mostly to determine the suitability of using native species at the mine site. Test plots <br />were used to simulate the disturbance that would result from surface mining. <br />The complete details of the four-year revegetation study are found in Exhibit 10, <br />Vegetation Information. <br />Also, in 1977 an additional shrub study was initiated in conjunction with the Soil <br />Conservation Service, Upper Colorado Environmental Plant Center. Approximately 35 <br />species of shrub seedlings from the Plant Materials Center were being evaluated for <br />potential use in mined land revegetation. <br />Field trials have been, and continue to be, an ongoing effort at Colowyo since these initial <br />studies indicated above (1975 and 1977). The most recent evaluation of efforts to <br />establish shrubs and trees in pre-2000 revegetation resulted in the following assessment <br />by Cedar Creek Associates, Inc. (2006): <br />"Given the assumptions presented, past and present shrub counts, as well <br />as 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 <br />a failure (<10% survival). Shrub populations or patches on an <br />overwhelming majority of reclaimed surfaces [prior to 20001 are well <br />below the [old] success standard of 1,000 woody plants per acre (except <br />within fenced enclosures) and a majority of the surviving shrubs in open <br />(unfenced) revegetation were not planted, but were apparently included in <br />the seed mix (i.e. Big Sagebrush - Artemisia tridentata). There is no doubt <br />4.15-4 Revision Date: 3/14/08 <br />Revision No.: TR-72