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WATER INFORMATION <br />1. Surface Water General Discussion <br />EX~IIBIT G <br />The site is located on a gravel terrace approximately 2/3 mile southwest and 180 feet higher in <br />elevation than the Uncompahgre River. The river is seen on Map B-1 to the northeast of the permit <br />area. The entire terrace is dry and no water will be encountered during mining. Water quality from the <br />closest USGS gage on the Uncompahgre River, located 1 mile upstream at the confluence of the <br />Uncompahgre River and the Selig Diversion, is included in Appendix B. The data shows that dilution <br />from various other tributaries in the basin result in overall good water quality, as is summarized <br />below: <br />pH: 8.0-8.4 <br />Ions in Concentrations of Concern: Selenium <br />Selenium is a dissolved ion of concern in the area, especially to fish populations. The CDPHE <br />determined that the level of selenium chronic to aquatic life is 4.6 µg/liter. The acute level is 18.4 <br />µg/liter. The USGS gage at the junction of the Uncompahgre River with Selig Diversion showed a <br />level of is 9.0 µg/liter in February of 1992. This is typical of the water in the Uncompahgre River. <br />Selenium loading in the river comes from a vast area of exposed Mancos Shale in the watershed and <br />the irrigation canals providing new contacts for water with shale. Since this operation will not mine to <br />the depth of shale and because of the distance and elevation difference to the river, it is not expected <br />to have any impact on the selenium concentrations in the River. <br />The only principal way that the gravel pit could affect the water quality of the groundwater is through <br />fuel leakage from a ruptured tank. As described in the mining plan, all portable fuel tanks will have <br />secondary containment and will be inspected frequently as required by the SPCC plan. <br />Haldorson Sand and Gravel Mine 27 <br />