2015-12-31_REPORT - C1981035 - Laserfiche WebLink

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change in the ionic profile of the water entering the Wiltze monitoring well. Other major anions, cations and pH trends all seem to remain unchanged. CDS is unable to provide an interpretation of this collection of trends, other than the introduction of a water source with different levels of Manganese and sulfate. • King II Up -gradient well — Sampled since 1/1/2005. The most evident trend is the lowering of the water table over the nearly ten year sampling period. The average depth to water dropped about twenty-five inches, but in 2015 rebounded a few inches.. This short term trend is also found in the King I — Wiltze Well, which is located about one mile to the east in the floor of Hay Gulch. As seen in the 2014 report, the chemistry of the up -gradient well has varied considerably during its almost ten years of sampling. For example, the levels of Magnesium and Manganese have increased about ten -fold, while the TDS remained almost level. Slight reductions are seen in Iron [from about 0.15 mg/L in 2005 down to non -detect in 2013-2014, but rebounded a bit in 2015. The slight statistical reduction in Sodium continues in 2015. • King II Down -gradient well — Samples since 1/1/2005. The single most striking observation seen in this monitoring well is the extreme variability of water depth. In four dry periods [2006 through 2008] the water level dropped to 100 inches or lower. These dry years were offset by three very wet years when the water level was very near the surface [2005 at 2 inches; 2008 at 22 inches and 2010 at 12 in inches]. In 2015, the level of water significantly increased, then decreased again demonstrating the high degree of variability seen over the years. Even with the down -gradient well's high degree of water depth variability all major anions and cations were almost unchanged. [the slight decrease shown may not be statistically valid]. • King II Hay Gulch Ditch — Sampled since 1/1/2005. As seen in other monitoring wells all tested parameters exhibit high degrees of variability from quarter to quarter and from year to year. When trend analysis is performed, the trends are essentially flat, for all monitored anions and cations, across the nearly ten year monitoring period. The notable exception is sulfate which demonstrated a reduction trend had a significant increase in 2015. This suggests an increase in leached sulfate from the sulfate laden soils [derived from shales and mudstones] that line the Hay Gulch alluvium. The variability of Hay Gulch Ditch measured parameters strongly resembles the dry years seen in the monitoring wells, suggesting the ditch also receives rain leachate in addition to the water it receives from the La Plata River.