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Geologic baseline information including: local and regional structure; stratigraphy; and information <br />on interburden, overburden and coal geochemistry is provided in Volume 2, Tab 6, of the permit <br />application. <br />Ground Water <br />Bedrock ground water aquifers have been identified as the Wolf Creek coal seam, the Wadge coal <br />seam, the Wadge overburden including the discontinuous Lennox coal seam and the Trout Creek <br />sandstone. Recharge to these and other aquifers in the area is a function of infiltration of snow melt <br />and rainfall at outcrops along the anticline. All aquifers exhibit water table conditions near the <br />outcrop. However, observation wells installed downdip indicate the aquifers are all under artesian <br />conditions with increased pressure related to increased depth. Quality in all aquifers is poor and <br />undesirable for use as either a drinking or irrigation supply. <br />The Seneca II-W Mine permit area lies on the western flank of the Sage Creek Anticline, a local <br />structure located within the more regional Sand Wash Basin. The Sage Creek Anticline is thought to <br />control local ground water flow, as artesian head increases with distance from the anticlinal axis. <br />Ground water occurs in the alluvium associated with Hubberson Gulch within and adjacent to the <br />permit boundary. Quality of this water prohibits its use for drinking and severely limits its use for <br />irrigation. Drinking water and irrigation standards were exceeded for TDS, Conductivity and <br />Manganese. <br />Surface Water <br />The mine permit boundary encompasses two surface watersheds. Most of the mine site and the <br />major portion of the disturbed area are in the Dry Creek watershed, and will drain into Hubberson <br />Gulch and an unnamed tributary to Dry Creek (the Pond 005 Gulch). A small area on the eastern <br />edge of the permit boundary drains to Sage Creek. <br />Flows on Sage Creek range from intermittent to perennial, depending on location and precipitation <br />patterns. At the Seneca H-W monitoring sites, Sage Creek can be classified as perennial during years <br />at or above average precipitation, and intermittent in years below average. The numerous small <br />drainages which are tributary to Dry Creek are ephemeral in nature. Hubberson Gulch, downstream <br />of the mine site to its confluence with Dry Creek, is intermittent. Dry Creek, like Sage Creek, can be <br />classified as perennial most years, and intermittent during years with below average precipitation. <br />Both Sage Creek and Dry Creek are confluent with the Yampa River near Hayden, Colorado. <br />Water in Hubberson Gulch is a MgCa-SO4 type. Surface water total dissolved solids (TDS) averages <br />820 mg/1. The water is hard, and is characterized as slightly alkaline (average pH 8.1). It is suitable <br />for livestock watering and irrigation of salt-tolerant crops grown in well drained soils. <br />Water quality in Sage Creek is a CaMg-IICO3 type. Samples from baseline monitoring points <br />indicate the water is slightly alkaline with a pH ranging between 7.0 and 8.0. The water has a TDS <br />Seneca II-W Findings Document 10 C1982057 <br />Permit Renewal No. 5 December 9, 2010