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• As shown on Figure 4, Water Table Level, the water table contours generally tend north- <br />south with a groundwater gradient to the east-northeast. This gradient is influenced by a <br />series of groundwater discharge plumes in the vicinity of the abandoned Gordon, Morning <br />Glory, and Maitland mines. A series of groundwater valleys separate these ridges and result <br />from dewatering by the mine workings. In general, the water table surface follows the <br />topographic surface, with a subdued water table topography. The permit area is underlain <br />by a single aquifer consisting of sediments of the Trinidad, Raton, and Vermejo formations. <br />Much of the transport takes place in the coal seams, through fractures. In addition, <br />groundwater transport occurs in the sandstones of the Trinidad formation and inter-sands <br />between coal seams. The aquifer is bounded on its lower extremity by heavy shales of the <br />Pierre formation, with the upper limit described by the water table. In local areas, <br />groundwater is under artisan conditions. This is especially important in some of the areas <br />along washes or arroyos, where the overlying colluvium, although beneath the piezometric <br />surface, is not saturated due to presence of underlying confining layers. <br />Almost no use is made of water contained in the aquifer within and adjacent to the permit <br />area. One family uses water from the aquifer (Well 27-67-24cc). A sample of water from <br />this well (Table 5, Results of Water Quality Analyses Samples from Existing Wells and <br />Monitoring Wells) was found to contain extremely high levels of sodium and sulfate. It is <br />recommended that the water from Well 27-67-24cc not be used for potable supply. <br />Two other wells within the area are used for stock watering. One of these, owned by <br />• Romula Archuleta (We1127-67-24bc), contains high concentrations of sodium and sulfate and <br />should not be considered adequate for potable supply. The other well, a windmill located <br />south of Maitland Arroyo (We1127-67-36ac), does contain potab]e quality water and is used <br />as a source of supply by local residents who haul water from the windmill for potable <br />consumption. <br />Previously, industrial water was obtained from a large diameter dug well located on the <br />north side of Gordon Arroyo and was used in the Gordon mining operation. A previous <br />USGS water quality sample from this source, collected in October 1949 and reported in <br />Colorado Groundwater Basic Data Report No. 4, indicates a total dissolved solids <br />concentration of 1,130 mg per liter, consisting predominantly of sodium sulfate and <br />bicarbonate. The well is still in place, but is not presently in use. <br />As previously noted, quality of subsurface water in and adjacent to the permit area is <br />generally poor. Figure 5, Groundwater Quality, illustrates that much of the groundwater <br />quality adjacent to the mine plan area is unsuitable for use, due to high sulfate concentra- <br />tions. A large area just north of the permit area contains groundwater with total dissolved <br />solids concentrations in excess of 10,000 mg/L. Water in the southern portion of the permit <br />area is of marginal quality, and contains high levels of sulfate. <br />A series of water quality samples were collected from existing domestic and livestock wells <br />within the area and from several monitoring wells as shown on Map 4, Surface and <br />. Groundwater Monitoring Locations. Results of chemical analyses of these sites are provided <br />2.04-35 <br />