2008-03-13_REPORT - C1981019 (2)

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population recruitment rates. The location of each unit and reference area evaluated in 2007 is indicated on Maps 1 & 2 and the sample points within each area are provided on "in-text" maps for each unit in Section 2.0. ', Field sampling for the directly measurable variables of ground cover, current annual production (selected units), and woody plant density was systematically conducted within all designated units from July 27th through August 2nd, 2007. The growing season prior to and during the sampling period could be qualitatively characterized as above average with regard to precipitation. Sampling occurred immediately following the peak of growth in July. Field efforts in 2007 were conducted under the direct supervision of Cedar Creek's Senior Range Ecologist, Mr. Steven R. Viert; Senior Plant Ecologist, Mr. Erik M. Mohr, and/or Range Ecologist, Mr. Jesse H. Dillon. The remainder of this document is divided into logical sections. Section 2.0 provides results by mine area (East Pit, West Pit) by revegetated unit. Each unit and resulting data /mapping is separately presented along with a brief discussion of any pertinent observations and/or recommendations. Section 2.0 also presents results of data collected from specific features on the ,mine, such as CSU Shrub Plots, • Permanent Shrub Plots, and Section 16 Informational data collection. Section 3.0 presents pertinent • conclusions and/or recommendations. A description of field methods utilized in 2007 is presented as Appendix AA, and raw data tables and charts are presented in Appendix AB. In this manner, only the • most salient information is provided in the main body of this document. Acreages presented in this • document are determined by Colowyo's engineering and/or permitting department. i Precipitation data presented on Table P and Chart P (following Maps 1 & 2) is the average of two weather stations at the Colowyo Mine (SCN16 and WSTPT). Precipitation in the project area was determined to be above average when compared with the seven-year average for the 2006 / 2007 growing season (September 2006 through August 2007). However, this seven-year average is potentially below the actual long-term average for the mine given that 2001 through 2004 are recognized as below- average precipitation years region wide (drought years). For example, the nearest official weather station (Craig 4SW) received only 44% of its average precipitation in 2001, 61% in 2002, 86% in 2003, and 83% in 2004. Given this analysis the long-term average precipitation at the Colowyo mine is most • likely in the 19 inch range as opposed to the recent seven-year average of 17.7 inches. Therefore, precipitation during the 2006 / 2007 growing season (20.22 inches) was most likely only slightly above • average as opposed to well above average. The growing season precipitation was about average with April, May, and June exhibiting 0.92, 1.67, and 0.30 inches, respectively. • r • Rio Tinto Energy America/Colowyo Mine Page 2 Revegetation Monitoring - 2007