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collecting cover data on previously reclaimed areas slated to be remined during 1987. These data will be used for comparison purposes in that the vegetative cover of the revegetated areas shall be considered acceptable if it is not less tfian 90% of the cover value from the 1987 sampling with 90% statistical confidence for at least the last two consecutive years of the ten year liability period. 2. Production - A technical standard will be used to determine success ra'~ er tian the upland sagebrush reference area because the over-abundance of woody plants in the reference area precludes an accurate measurement against the predominant herbaceous community of the reclaimed areas. The technical standard is based on the dominant soils present in the Nucla Mine area as recently determined by the Soil Conservation Service (SCS) in the soil survey of Western Montrose and San Miguel Counties. For the areas satisfying the requirements of Rule 4.15.6, two different production standards will be used based upon the minimum amount of topsoil replaced. For all of the dryland pasture areas and the rangeland areas receiving ten inches of topsoil, herbaceous production will be considered acceptable if it is not less than 90% of 500 pounds per acre with 90% statistical confidence for at least the last two consecutive years of the ten year liability period. The 500 pounds per acre is the potential productivity in favorable years for the Shavano soil series as determined by the SCS. The Shavano series is the dominant soil occupying about 73% of the affected area. For all other areas satisfying the requirements of Rule 4.15.6, herbaceous production will be considered acceptable if it is not less than 90% of 250 pounds per acre with 90% statistical confidence for the required years of the liability period. The 250 pounds per acre is the potential production in normal years for the Persayo soils which occupy the remaining approximate 27% of the affected area. For the areas satisfying the requirements of Rule 4,15.10, there are no production standards that these areas must satisfy. 3. S ecies Diversity - The species diversity standard was developed by eva uating t e re ative importance of plant species in the upland sagebrush reference area with a minimum value set at three percent relative cover. A total of seven species have relative cover value greater than three percent: three grasses, two shrubs, one succulent and one annual grass. Two of these growth forms, succulent and annual grass, were dropped from consideration since they are not practical components of the reclaimed areas. Based upon the upland sagebrush reference areas, the species diversity standard to be achieved is three grasses, one forb and one shrub with relative cover of three percent or greater but no one species with relative cover greater than 40 percent. Also, the combined relative cover of these species will not be greater than 85 percent. For the areas satisfying the requirements of Rule 4.15.10, there are no species diversity standards that these areas must satisfy. -24-