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each monitoring site is presented on Tables 1 through 55 and 57 through 71. Data measurements from 2004, • which are above or below previously documented data ranges have been highlighted in these tables. Table 56 provides a historical summary of flow rate data far the surface water monitoring sites. Figures 3 through 133 provide graphical representations of selected data. Figure 121 presents data documented during the 2004 Mine Inflow Study. Statistical summaries of the historical data base are provided after presentation of the 2004 data. Statistical summaries of water levels or flows are presented as well. Note that in 2003, DMG approved TR03-42 (See Permit Exhibizs 14-5, 14-6, and 14-10), and PR 03-06 (See Pemvt Exhibits 14-7 through 14-9), which eliminated some surface, alluvia], and bedrock well monitoring sites, and reduced the monitoring frequency of other sites, while adding additional monitoring requirements [o existing surface site 305. 2003 data from terminated sites is provided in this AHR, however tables and figures for these sites will be purged from future AHRs. Specific changes resulting from TR03-42 and PR03-06 are discussed in [he following sections. 3.1 Bedrock Groundwater MonitorinP Hvdroeeoloev; TCC's underground mining operations are located on the southwest flank of the Twentymile Park Basin. This is an enclosed synclinal ground water basin, rimmed by outcrops of major lithologic units. Ground water in the Twentymile Park Basin exists primarily under confined conditions within the bedrock units. All ground water aquifers in the general area, except the alluvia] aquifers, are recharged by infilvation in outcrop areas, located primarily in the southern and western margins of the Twentymile Park Basin. Recharge is limited, • due to ]ow average annual precipitation and the loss of moisture through evapotranspiration and sublimation in this semi-arid climatic zone. Ground water occurrence and movement within the bedrock aquifer system is controlled by geologic structure and lithology. Ground water movement tends to follow the structural dip of the lithologic units toward the basin axis. The general vend of movement in the permit area is to the north and northwest. This results in confined aquifer conditions down gradient from the outcrop area. A detailed discussion of the geo]ogy/hydrology for the site is available in the Twentymile Coal Company, Foidel Creek Mine Permit C-82-056, Volume 1, Rules 2.04.6 and 2.04.7. The Twentymile Park Basin is underlain by a large, high quality coal reserve. This reserve, mined by underground operations, is known as the Wadge Seam. The Wadge Seam lies within a sequence of sedimentary rocks characterized by shales, claystones, mudstones, siltstones, sandstones, and minor coal stringers referred to as the Wadge Overburden. The Wadge Overburden is hydrologically isolated from the two major bedrock aquifer units in the Twentymile Park Basin, the Twentymile Sandstone aquifer and the Trout Creek Sandstone aquifer, which lie above and below the Wadge Overburden, respectively. Lying above the Twentymile Sandstone is a minor aquifer unit, known as the Fish Creek Sandstone. All these geologic units are monitored within the Foidel Creek Mine permit area. The Wadge Overburden is directly affected by the mining operation. Dewatering of this zone in the area of mine operations is currently being conducted. The Wadge Overburden lies approximately 1100 feet below the ground • surface. The Wadge Overburden sequence varies in thickness from 50 to 100 feet, averaging approximately 75 3