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<br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />1 <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />TECHNICAL MEMORANDUM <br />AmerAlia, Inc. <br />October 19, 1999 <br />Page 9 <br />4.2 Corral Gulch <br />Upper and lower Corral Gulch gaging stations (#09306242 and #09306244) have periods of record from <br />1974 to present and 1976 to 1977, respectively. Flow data indicate that Corral Gulch is perennial but <br />may become intermittent in the lower reaches during dry years. At the upper station, the average daily <br />flow was 2.24 cfs with a maximum of 207 cfs and minimum of 0.06 cfs. The average flow at the lower <br />Corral Gulch station for the two years of record was 0.11 cfs with a maximum of 9 cfs and minimum of <br />zero cfs. During a project site inspection on September 8, 1999, the flow of lower Corral Gulch near the <br />confluence with Stake Springs Draw was estimated as approximately 0.2 cfs. <br />Corral Gulch water quality is a mixed magnesium sodium bicarbonate type at the Upper Corral Gulch <br />USGS monitoring site, and a magnesium sodium sulfate bicarbonate type at the mouth of Corral Gulch <br />(Zook and Sares, 1999, and Tobin et al., 1985). Water type Corral Gulch is presented in a Piper Diagram <br />in Appendix B. Average TDS concentrations exceed agricultural water quality standards, and maximum <br />values of fluoride and manganese exceed agricultural water quality standards. <br />Electric conductivity, TDS and pH have stayed fairly constant in Corral Gulch since monitoring was <br />started. However, some seasonal effects are apparent. Electric conductivity and TDS are lowest during <br />the month of February. Graphs for long-term monitored data and monthly averages are contained in <br />Appendix C. In Corral Gulch no correlation between flow and water quality was found (Appendix C). <br />4.3 Stakes Springs Draw <br />The Stake Springs Draw gaging station (#09306230) has a period of record from 1974 to 1977. Stake <br />Springs Draw is an intermittent drainage with perennial flows in the upper reaches. The stream at the <br />mouth is dry during periods of low precipitation. During the period of record, average daily discharge of <br />Stake Springs Draw was 0.02 cfs with a maximum of 11 cfs and a minimum of zero. During a project <br />site inspection on September 8, 1999, the flow in Stake Springs Draw above the confluence of Corral <br />Gulch was estimated as approximately 0.1 cfs. <br />Stake Springs Draw water quality is a calcium bicarbonate type with a pH of 8.0 and low concentrations <br />of TDS and trace constituents (Zook and Sares, 1999). <br />2ndPinalTechnical Memo.doc 10/19/99 TRC HYDRO-GEO CONSULTANTS <br />