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the high was recorded at monitoring well TR-1.5 in August with a value of 0.60 mg/L. The <br />lowest manganese concentration in 2008 was recorded at monitoring well TR-3 in May with a <br />value of <0.005 mg/L and the high was recorded at monitoring well TR-4 in October with a <br />value of 3.50 mg/L. <br />?. 4.2.7 Ground Water Orthophosphate and Nitrite <br />Charts 34 and 35 show orthophosphate and nitrite concentrations for the monitoring wells TR- <br />1.5, TR-3, TR-4, WR-1 and TCS-1 for the period of record. Historically, orthophosphate and <br />nitrite values obtained over the period of record have been low with most being below <br />detection limits. Elevated orthophosphate readings occurred in the summers of 1998 through <br />2000, at up-gradient well TR-1.5, possibly due to nearby agricultural activity. In 2001, <br />concentrations of orthophosphate returned to historically low levels. Site TR-4 had a slight <br />' rise in orthophosphate concentration during the 2005 monitoring period, but decreased to <br />levels similar to previous sampling events during the past few years. Nitrite concentrations <br />were again elevated at TR-1.5 in May 2000 and May 2001 and at WR-1 in May 2001, but <br />decreased to historical levels as the year progressed. Nitrite levels remained at historical <br />levels in the 2008 monitoring period. The lowest orthophosphate concentration in 2008 was <br />recorded at numerous monitoring wells during numerous events with a value of <0.01 mg/L <br />' and the high was recorded at monitoring wells TR-1.5, TR-4 and WR-1 in May with a value <br />of 0.04 mg/L. The lowest nitrite concentration in 2008 was recorded at numerous monitoring <br />wells during numerous events with a value of <0.01 mg/L and the high was recorded at <br />monitoring well TR-4 in August with a value of 0.05 mg/L. <br />4.2.8 Ground Water Chloride and Potassium <br />Charts 36 and 37 show chloride and potassium concentrations for the monitoring wells TR- <br />1.5, TR-3, TR-4, WR-1 and TCS-1 for the period of record. Chloride and Potassium were <br />added to the parameters list in 1994. Potassium levels increased in TR-4 over the course of <br />2003, but have leveled off over the last few years. Chloride at TR-4 spiked in both October <br />2004 and May 2005, however concentrations returned to historical levels over the past few <br />monitoring periods. Chloride has risen over the past 4 monitoring seasons at TCS-1. The <br />lowest chloride concentration in 2008 was recorded at monitoring well WR-1 in May with a <br />value of <1 mg/L and the high was recorded at monitoring well TCS-1 in May with a value of <br />94 mg/L. The lowest potassium concentration in 2008 was recorded at monitoring well TR-3 <br />in May with a value of 0.6 mg/L and the high was recorded at monitoring well WR-1 in <br />October with a value of 10.9 mg/L. <br />5.0 Surface Water and Ground Water Interactions <br />The interrelationship in concentrations of chemical parameters between the surface waters and <br />alluvial waters at the Edna Mine can only be suggested in very general terms. The primary <br />reasons for this are the relative location of a given well to the creek, the source from which an <br />alluvial well's water originates and the dynamics of alluvial flow. <br />13