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irrigated pasture aeeas in the PR-OS revision azea indicated only slightly higher <br />cover levels (mean cover 76.8%), despite growing season precipitation which <br />was 177% of normal during 1999, prior to sampling. The original cover standazd <br />will be sufficient to control erosion, and will remain in effect for the Mine 2 azea, <br />including the PR-OS revision area. Successful cover establishment will be <br />demonstrated when live vegetation cover is no[ less than 90% of 71.8%, with 90 <br />percent statistical confidence. <br />The success standazd for dryland pasture is based on a cover comparison with a <br />new dryland pasture reference area established in 1999, which is described in <br />Section 2.04.9, with location shown in Attachment 2.05.4(2)(e)-2. The new <br />reference area more closely represents the proposed postmine vegetation than the <br />sagebrush reference azea previously utilized. The new reference azea supports <br />established introduced dryland pasture grasses on BLM managed land in the <br />permit azea vicinity. Successful cover establishment will be demonstrated when <br />live vegetation cover on the reclaimed area is not less than 90% of the reference <br />azea cover, with 90% statistical confidence. <br />A cover success standazd for irrigated hayland is not applicable because <br />revegetation success is only dependent on production. <br />2. Production -The production success standazd for irrigated hayland in the New <br />Horizon 2 azea is a technical standazd based on a combination of permit azea <br />landowner estimates, NRCS evaluation, and landowner production records for <br />1987 and 1999, for alfalfa hayland first cutting production. Yield estimates and <br />records for the permit area landowners, and a June, 19981etter from the NRCS <br />supportive of a production standazd of 1.84 tons/acre/yeaz, for ls` cutting irrigated <br />hayland production, are included in Attachment 2.05.4(2)(E)-A, of the permit <br />application. Irrigated hayland production success will be demonstrated when the <br />production mean based on sampling is not less than 90% of 1.84 tons per acre, <br />with 90% statistical confidence. Alternatively, success will be demonstrated <br />when production based on total harvest (ls` cutting) is not less than 90% of 1.84 <br />tons per acre. <br />The success standazd for irrigated pasture areas is a technical standazd based on <br />the same combination of landowner estimates, production records, and NRCS <br />evaluation as described for irrigated hayland. The standazd for irrigated pasture is <br />1.5 tons per acre/yeaz, for ls` cutting production. Irrigated production success <br />will be demonstrated when the production mean based on sampling is not less <br />than 90% of 1.5 tons/acre/year, with 90% statistical confidence. Alternatively, <br />success will be demonstrated when production based on total harvest (151 cutting) <br />is not less than 90% of 1.5 tons per acre. <br />The success standard for dryland pasture aeeas in the New Horizon Mine 2 azea <br />will be based on comparison to herbaceous production in the dryland pasture <br />34 <br />