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Whirlwind Mine Groundwater Characterization Report <br /> The area is characterized by high and to semi-arid mesas dissected by deep narrow canyons <br /> that have formed within gently dipping Mesozoic sedimentary rocks. Most drainages in the area <br /> are ephemeral in nature and exhibit surface water flow only during, or shortly after, substantial <br /> precipitation events. The Dolores River, located three miles to the east, is the main high-order <br /> stream and receives runoff from John Brown and Lumsden Canyons which originate at the <br /> western edge of Beaver Mesa within the Gateway Mining District. <br /> Vegetation in the region consists of high desert pinon-juniper woodland or steppes. <br /> Predominant conifers include Utah juniper Uuniperus osteosperma) and Colorado Pinon (pinus <br /> edulis). A relative abundance of other mid-story cover shrubs includes mountain mahogany <br /> (Cercocarpus ledifolius), Utah service berry (Amelanchier utahensis), rubber rabbit brush <br /> (Chrysothamnus nauseosus), four-wing saltbush (Atriplex canescens), greasewood <br /> (Sarcobatus), Mormon tea (Ephedra), yucca (Asparagaceae family), broom snakeweed <br /> (Gutierrezia sarothrae), and big sagebrush (Artemisia tridentate) to name a few. Ground cover <br /> plants include cacti and various wildflowers and grasses. <br /> The elevation of the Dolores River near Gateway is 4,560 ft above mean sea level (AMSL), <br /> whereas the elevation of the Whirlwind Mine portal is 7,087 ft AMSL. The top elevation of <br /> Beaver Mesa is approximately 7,800 ft AMSL. <br /> Precipitation in the region is elevation dependent and can be approximated using climatic data <br /> from the Glade Park, Colorado, Station USC00053307 as monitored by the Utah State <br /> University Climate Center. The Glade Park station is approximately 30 miles to the northeast of <br /> the Whirlwind Mine at an elevation of 6,323 ft AMSL. The average annual precipitation for the <br /> period of record 1999 to 2022 (present) is 13.39 inches, with June and October showing the <br /> average least and greatest amounts of precipitation at 0.58 and 1.57 inches, respectively (Utah <br /> State University, 2022). The low and high mean daily temperatures at the Glade Park Station <br /> are 25.10 and 72.50 OF during the months of January and July, respectively. <br /> 3.0 GEOLOGIC SETTING <br /> The Whirlwind Mine is located within the east and east-central portion of the Colorado Plateau <br /> geologic province, an area of generally flat lying Paleozoic and Mesozoic rocks that have been <br /> gently folded and faulted, with local areas of Tertiary intrusives to the west and anticlinal <br /> Western Water& Land, Inc. 5 <br />