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i ~ <br />TABLE 3. Average concentration of major cations and anions, Dolores River surface <br />water, USGS upstream gauge near Bedrock Colorado. <br />Parameter Units Value Comment <br />Temperature °C 14.4 25.9° F. Average temperature <br /> meets standard. A few temp <br /> measurements in data set exceed T° <br /> max for both cold and warm water <br /> aquatic life. <br />Conductivity µ-Siemems/cm 675 Moderate conductivity <br />pH Standard units 83 Slightly alkaline. Meets surface <br /> water quality standard <br />Ca mg/L 55 <br />Mg mg/L 15 <br />Na mg/L 59 <br />K mg/L 3.28 <br />Cl mg/L 69 <br />SO4 mg/L 120 Meets secondary drinking water <br /> standard <br />F mg/L 0.148 Meets primary drinking water <br /> standard <br />Si mg/L 4 <br />TDS mg/L 481 Not regulated in surface water. <br /> Slightly saline. Within low TDS <br /> category for groundwater. <br />The elevated sodium and chloride probably derive from dissolution of halite, not exposed <br />at the surface but present in the regional stratigraphy. Salty-tasting drinking water in <br />public water in Dolores suggest that halite dissolution originates somewhere upstream <br />from the local drinking water source. <br />Some salinity values at the Bedrock Colorado station, while within water quality limits, do <br />exceed nonmandatory goals for water quality. Hem, 1992, cites recommended TDS <br />criteria from the US Public Health Service and the American Water Well Association as <br />follows: <br /> <br />