2014-05-12_PERMIT FILE - C2010089 (3)

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REGIONAL SURFACE WATER CHARACTERISTICS The NHN permit area is drained by tributaries of Tuttle Draw and tributaries of Coal Creek Canyon. Map 2.04.5 -1 in Section 2.04.5 shows the relationship of Tuttle Draw and Coal Creek Canyon to the NHN Permit area. The drainage divide between Tuttle Draw and Coal Creek crosses the permit area from northeast to southwest and is roughly traced by the location of the 2 Park Lateral irrigation ditch, (see Maps 2.04.5 -1 and 2.04.7 -1). To the south and east of the divide, the permit area is drained by a tributary, referred to as Nygren Draw, which in turn drains into Tuttle Draw. North and west of the divide, the permit area drains into tributaries referred to as Meehan Draw and Glasier Draw which in turn drain into Coal Creek Canyon, (see above referenced maps). These three tributaries do have perennial flow as they act as return water drains from the 2 Park Lateral flood irrigation runoff and seepage. Both Tuttle Draw and Coal Creek are perennial tributaries of the San Miguel River which in turn flows into the Dolores River and finally to the Colorado River. These river systems are explained thoroughly in Iorns' et al. (1965) USGS Professional Paper, Water Resources of the Upper Colorado River Basin - Technical Report. The New Horizon 1 Area and New Horizon 2 Area mining permits provide a detailed description of the characteristics of the region surface water systems. Regional Surface Water Flow The precipitation that falls on the basins within the Upper Grand Division of the Colorado is generated from large air masses originating from the Pacific Ocean and the Gulf of Mexico. These air masses originating from these sources are pushed high into the atmosphere, losing much of their moisture prior to entering these basins. The Pacific air masses dominate from October through April, and the Gulf of Mexico air masses dominate during late spring and summer. The higher stream flows within the Grand Division largely result from snowmelt during late spring and early summer By late July, most stream discharges recede to base flow. Little contributions are made to stream discharges resulting from the infrequent summer thunderstorms. In the lower altitudes of the subdivision between the Gunnison and Green Rivers, little snow accumulates during the winter months; therefore, most spring runoff events occur principally in the head waters of the Dolores, San Miguel Rivers, and in the La Sal Mountains. On a more local basis, short duration, high intensity thunderstorms that fall on undeveloped (natural) watersheds provide some of the summer runoff. In addition, return water from irrigation, and water from localized ground -water reservoirs augment stream flow during the summer months. Ground water also contributes to the stream base flow during the summer months. The San Miguel River at Naturita, Colorado has a drainage area of 1,080 square miles Iorns, et. al. (1965a), presents a flow - duration curve developed for the San Miguel River at Naturita based on historic stream flow records. The curve indicates that 90 percent of the time, discharge exceeds 60 cfs, and that flows larger than 1000 cfs occur only 10 percent of the time. USGS Surface Water Records for the San Miguel at the Brooks Bridge (0.5 mi. upstream of Nucla Station) show the mean flow of 252 cfs for Water Year of 2009 and a mean flow for Calendar Year 2008 of 316 cfs. The mean flow for water years 1995 -2009 is 247 cfs with lowest mean for the period of 59.1 cfs which occurred in 2002. The highest mean flow for the period is 499 cfs which occurred in 1997. The highest daily mean flow for the 1995 to 2009 period was 2,370 which occurred on 6/17/1995. This compares with the highest daily mean flow at Brooks Bridge Section 2.04.7 Page 14 November 2011