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concentrations as high as 5700 mg/1, S26-S which reached levels as high as 4300 <br />mg/l but has dropped off to around 3500 mg/1, and S27-S which, has climbed <br />gradually to about 3300 mg/l TDS. Spoil springs show the same range of <br />concentrations as the wells. <br />In 1977, the Water Resources Division of the United States Geological Survey <br />(USGS) began a lysimeter study at the Seneca II Mine to determine spoil aquifer <br />discharge quality, and how that quality changes over time. Stipulation No. 23 in <br />the original permit required the applicant to submit the USGS report to the <br />Division upon its completion. In 1994, the USGS published Water-Resources <br />Investigations Report 92-4187 titled, Hydrology and Geochemistry of a Surface <br />Coal Mine in Northwestern Colorado. The report describes the sources of <br />hydrologic recharge to and from reclaimed spoil, the relative contributions of <br />recharge to the reclaimed spoil aquifer from identified source waters, and the <br />water movement and geochemical reactions that control water quality in reclaimed <br />spoil. <br />Native Springs <br />Four native springs exist within the original permit area: Springs #1, 2, 3 and 5. <br />Spring #4 is outside the permit area and is no longer sampled. Seneca previously <br />discontinued monitoring of all natural springs at the Seneca II Mine. Springs #1 <br />and #2 exist in a pre-SMCRA area and springs #3 and #5 are poorly defined seeps <br />in a seasonally marshy area. None of the native springs exist within the reduced <br />permit area. <br />4nrface Water <br />The applicant will conduct monitoring of surface water in a manner approved by <br />the Division. The monitoring plan was submitted under 2.05.6(3)(b)(iv) and is <br />discussed on page 2.04.7-2 of the PAP. Surface water hydrology information can <br />be found in Volumes 4, 5, and 6, Tab 7 of the permit application, and in the <br />Annual Hydrology Reports submitted by Seneca Coal Company. The monitoring <br />plan for the reduced permit area is discussed on page 2.04.7-2 of the PAP. <br />The Seneca II Mine is located between the drainage basins of Grassy Creek and <br />Fish Creek. Both of these are sub-basins of the upper Yampa River basin in <br />northwestern Colorado. Mining areas in the original permit area were within the <br />Grassy Creek and Fish Creek basins. The reduced permit area will affect only the <br />Fish Creek basin. <br />Fish Creek Basin <br />Seneca Coal Company originally monitored seven surface water sites in the Fish <br />Creek basin. NPDES 004 and Sites 6 and 10 are located on Cow Camp Creek. <br />15