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Permian rocks of the Central Oklahoma aquifer from nine cored test holes were analyzed to determine their mineralogical composition and petrographic characteristics. Eight of the holes were sited in areas where ground water is known to contain concentrations of arsenic, chromium, selenium, or gross residual-alpha-particle activities that exceed public drinking water standards; the nineth hole is located in an area of generally good water quality. The Permian clastic sedimentary units sampled by the test holes included 1) the Hennessey Group, 2) the Garber Sandstone and Wellington Formation, and 3) the Chase, Council-Grove and Admire Groups. Whole-rock mineralogy was determined for 196 samples; 70 samples were analyzed for clay mineralogy and 160 thin sections were point counted.Sandstones in the aquifer are quartz arenites to sublitharenites. Quartz and illite-rich clays are the dominant detrital constituents. Plagioclase, dolostone, potassium feldspars, chert, metamorphic rock fragments, and chlorite are minor detrital phases. Common authigenic minerals in the rock include barite, calcite, dolomite, goethite, hematite, kaolinite, and quartz as overgrowths. All of the units sampled have similar compositions, although the core from the test hole sited in an area of good water quality lacked dolomite, chlorite, and plagioclase. Results of these analyses will be used in future reports to describe and interpret rock-water interaction within the aquifer.

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Iron Mountain is located in the West Shasta Mining District in California. An investigation of the generation of acid rock drainage and metals loading to Boulder Creek at Iron Mountain was conducted. As part of that investigation, a hydrograph separation technique was used to determine the contribution of ground water to total flow in Boulder Creek. During high-flow storm events in the winter months, peak flow in Boulder Creek can exceed 22.7 m3/sec, and comprises surface runoff, interflow, and ground water discharge. A hydrograph separation technique was used to estimate ground water discharge into Boulder Creek during high-flow conditions. Total ground water discharge to the creek approaches 0.31 m3/sec during the high-flow season. The hydrograph separation technique combined with an extensive field data set provided reasonable estimates of ground water discharge. These estimates are useful for other investigations, such as determining a corresponding metals load from the metal-rich ground water found at Iron Mountain and thus contributing to remedial alternatives.