2009-08-13_PERMIT FILE - C1981019A (4)

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RULE 2 PERMITS • SAGEBRUSH REFERENCE AREA Colowyo will use the originally established Sagebrush Reference Area (C-SBA-1981) for weighted future revegetation success compazisons in the Lower Wilson disturbance azeas. Colowyo will use the C-SBA as the sole "targeted" reference area for ground cover and production testing for all South Taylor disturbance areas as delineated by the green tie-in boundary shown on Map 23A pursuant to Section 4.15.7(3)(b)(iii). Colowyo has determined to use this reference area in this manner instead of the "Hamer established" South Taylor Sagebrush Reference Area (ST-SBA) for eight reasons as follows. First, the C-SBA is readily accessible (located neaz the Administration Building) and should remain accessible during the life-of-mining. The ST-SBA is located high in the rugged terrain south of the Lower Wilson project area where access may be intermittently or permanently interrupted by mine- related activity. Second, the C-SBA has been measured more frequently over the past several years and therefore, presents a more extensive historic data-base. C-SBA data indicated for the third point below come from the 2005 sampling effort from the C-SBA and new tables providing these data have been provided as Tables 2.04.10-28 through 2.04.10-32. Third, an analysis of data indicates that the C-SBA more closely resembles the South Taylor Study Area than the ST-SBA with respect to dominant species and lifeform composition. Big sagebrush (Artemisia tridentata) comprises 28% and 27% of the C-SBA and South Taylor Study Area's vegetation composition, respectively, while comprising only 13% (less than half) of the ST-SBA vegetation. To the contrary, deciduous shrubs comprise twice (29%) of the ST-SBA vegetative composition but only 17% • and 5% of the Study Area and C-SBA's composition. And finally, perennial grasses comprise only 24% of the ST-SBA vegetative composition while comprising 32% and 40% of the Study Area and C-SBA's composition. In this regard, the C-SBA would be considered a better ecological target for reclamation attempting to re-establish sage and grassland communities. Fourth, (and of elevated significance) it appears the ST-SBA is located in an ecotone between the more mesic mountain shrub community type and the mesic sagebrush community type based on composition data, narrative descriptions, and photographs presented by Horner in his 1984 report. Hamer describes this area as the sagebrush-snowberry phase, which exhibits deeper more productive soils than the sagebrush - wheatgrass phase more typical of most Colowyo disturbances. The ST-SBA is surrounded and being invaded by mesic mountain shrub that will most likely continue to expand into, and replace, the sagebrush community as succession progresses. This observation is also verified by review of 2005 aerial imagery of the communities within and adjacent to the ST-SBA. Over the 21 years since the original mapping, the area that could be segregated as sagebrush has substantially diminished in azeal extent. To the contrary, the C-SBA is located in a lazge expanse of the sagebrush - wheatgrass phase with occasional patches of the mountain shrub community in draws and depressions and the more shallow-soiled juniper ' scrub community in rock outcrop areas. Very few compositional changes in the dominant taxa are expected in this area as succession progresses. Furthermore, this sagebrush-wheatgrass phase of the sage community is a more appropriate ecological comparator given the similazity of this area's underlying soil profile with the constructed growth media profile of Colowyo's reclaimed land. Fifth, based on statistical testing per current CDRMS guidelines, the ST-SBA is not comparable to the South Taylor Study Area for either cover or production (see Table 2.04.10-27) but is eligible as a reference azea only because values are higher than those found in the study area. The sampling adequacy • and equivalency procedures used by Hamer in 1984 were more liberal for such evaluations. Sixth, a review of data presented on Figures 2.04.10 - 7 and 8 indicated that Harner's 1984 data for the so°m Tay~or/Lower wf~son - xu~e z, Pzge ~9 Revision Date: 4/16/07 Revision No.: PR-02