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fluoride, the two wells (8P1 and 19) that have elevated levels have <br />historically displayed high levels. Those wells are also unique in <br />displaying a sodium bicarbonate type water; with almost no calcium, <br />magnesium, or sulfates; and with relatively high pH values. It is <br />suspected that the high fluoride values are related to this type ?of <br />water chemistry (Hem, 1989, pg. 121). All wells exist within the Seneca <br />II permit boundary. <br />In the case of iron, the one Wadge Underburden well (7) exhibiting high <br />levels may have higher than usual concentrations of iron pyrite in the <br />rock. The high levels of iron displayed in alluvial well 33 may be the <br />result of organic matter and plant debris present in the alluvium (Hem, <br />1989, pg. 77). These wells have historically exhibited high iron values <br />and all exist within, or upstream of, the Seneca II permit boundary. <br />High manganese values may, in part, be due to recharge from the spoil <br />aquifer, although high values are often common, especially in alluvial <br />material (Hem, 1989, pgs. 86-89). Manganese exceedances have occurred <br />at all alluvial wells, including the one Grassy Creek alluvial well <br />upstream of Seneca II (Well 71). This standard is used to protect crops <br />grown in soils with a pH value lower than 6.0. In January 2008, CDPHE <br />revised their ground water agricultural standard to reflect this pH <br />qualifier. In soils with a higher pH (as are found in the Seneca II <br />region), a more appropriate standard would be 10 mg/l (EPA, 1976). This <br />year, none of the Seneca II alluvial wells displayed a value higher than <br />4.28 mg/l, and no spoil wells displayed a value higher than 1.55 mg/1. <br />Three spoil wells (26, 27 and 61) exceeded the selenium standard, 20 <br />ug/1. These appear to be transitory excursions. Selenium values from <br />these wells before and after this event were all less than the standard. <br />Finally, water quality analyses performed on samples obtained at the <br />Seneca II shop well (STC5) for this year were compared against both <br />human health (mandatory) and secondary (i.e., recommended but not <br />mandatory) drinking water standards developed for ground water by the <br />CDPHE. No human health standards were exceeded. The CDPHE secondary <br />7