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Irrigated Pasture Success Standards <br />The success standard for cover is based on the level of premining ground cover (live vegetation) <br />determined from the 1987 and 1999 baseline studies conducted within the New Horizon 2 study <br />area (se ection 2.04.10). The average live vegetation cover determined from the 1987 study <br />w s 71.8 erce t. In 1999 the average live vegetation cover was 76.8 percent. These values <br />represent long term established perennial vegetation, reflecting a reasonably. constant value <br />because of historic irrigation and management. The difference in vegetative cover is attributable <br />to the difference in precipitation levels. As referred to earlier, 1999 was a very wet year during the <br />1999 growing season and the winter of 1998-1999 was mild. NRCS climate data for the San Miguel <br />basin indicates that precipitation is currently 177% of normal. NOAA data, current through April <br />of 1999 (Sec. 2.04.10, Tables 2.04.10-1 and 10-2) indicates a dry mild winter with a large increase <br />in precipitation for April. While the data is not available for May through August this trend of higher <br />than normal was verified by local residents in the Nucla area. Fluctuations in vegetative cover are <br />relatively small because irrigation has eliminated much the precipitation variation from yearly <br />fluctuations normally encountered in the semi-arid climate in the Nucla area. Some fluctuation in <br />live canopy cover is expected as precipitation effects areas inadequately covered by flood irrigation <br />and the resultant effect would be to suppress or promote vegetative cover uniformly over a pasture. <br />Temperature fluctuations have the same relative effect. During colder more severe climate years <br />vegetative cover would be suppressed or promoted with the respective severity or mildness of the <br />climate for a particular year. At the high levels of production achievable under properly managed <br />irrigated pasture, and specified in the production standard, the vegetation and ground cover will be <br />more than adequate to meet the requirements of 4.15.1(2)(b). Since 1999 was an abnormal year <br />climatologically, the success standard for cover will b!? - 91'.8 ercent ground cover for both the <br />original permit and the proposed permit expansion area. <br />Vegetation cover and herbaceous production will be measured at reclaimed sites and compared <br />to the reference standards to determine revegetation success, as described below. Vegetation <br />cover will be measured as either canopy cover or basal cover of living herbaceous vegetation, as <br />defined by CDMG Regulation 4.15.8(3)(b). Herbaceous production will be measured as current <br />year above-ground biomass of herbaceous vegetation, as defined by CDMG Regulation 4.15.8(4). <br />(Revised August 2006) 2.05.4(2)(e)-27