2011-01-13_REVISION - C1980006 (9)

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the draws is predominately composed of clay with isolated sand and gravel lenses. Wells have been strategically placed to intersect these lenses. To date, the calcium bicarbonate water quality does not appear to have been altered by the mine. There are currently no wells along the Canadian River alluvium east and northeast of the mine. The alluvium along the Illinois River near the loadout is less than 25 feet thick. Underflow is estimated at 1.5 acre-feet per day on material with permeability estimated to be 2,500 gpd/ft2. The water quality was initially characterized as calcium bicarbonate water with small concentrations of iron, magnesium sulfate, and nitrates. Surface Water The general area, which includes the mine plan area, is drained by the Canadian River, a perennial stream that flows northward into the North Platte River at Northgate, Colorado. The Canadian River drains 114 square miles between USGS Stations 06619400, upstream of mining activities, and 06619450 downstream of mining activities. The drainage area between these two monitoring stations includes the Marr Mine plan area, other abandoned and reclaimed mines, and various agricultural enterprises. The agricultural usages of land surrounding the mine plan area are primarily non-irrigated rangeland. Lands immediately paralleling and of varying widths along the Canadian River have been classified meadowland. A portion of the meadowland is cut for hay. This land is not shown precisely as various acreages in each category. Along the draws downstream from the permit area, there are no indications that this area is used for anything but rangeland. The Canadian River has a recorded average base flow rate of four cfs. The recorded water flow rate has reached 200 cfs during the snowmelt/rainfall period. Most of the water received in this river comes from snowmelt in the Medicine Bow Range to the east. Spring flooding decreases gradually in July and August to the base level. Canadian River water quality samples taken upstream of mining activities at USGS Station 06619400 contain predominantly calcium and bicarbonate ions. Water quality samples taken downstream from mining activity at USGS Station 06619450 show slightly higher concentrations of magnesium, sulfate, and nitrogen (N02 and N03). The nitrogen increases are attributed to agricultural practices in the area. The permit application states that the higher concentrations of magnesium and sulfate can be partially attributed to mining activities of the area. Tables 13 and 14 of the permit application detail these water quality data. The mine plan area is drained by ephemeral and intermittent stream systems, including (in order from north to south) Sudduth, Williams, Bush, and Bolton Draws with watershed areas of 3.6, 4.6, 4.8, and 6.8 square miles, respectively. Bolton Draw lies to the south of the permit area and could possibly be impacted by waters from the mine plan area during heavy runoff events. The streams in the Marr Mine area roughly parallel each other and flow to the northeast where they join the Canadian River, approximately one mile east of the permit area. In 1979, USGS Station 06619420 was installed in 18