Heavy Metal Concentration in the Water and Sediment of the Lake Greenwood Watershed

We report on the concentration of heavy metals (cadmium, chromium, cobalt, copper, iron, and lead) in the water and sediment of Lake Greenwood and the streams and creeks that flow into the lake. Our results show heavy metal concentrations well below levels that were reported in 2012. The heavy metal concentrations reported for Lake Greenwood were on the order of the established background levels; our measurements indicate that heavy metal concentrations are now well below the established background levels. The concentration of heavy metals in creeks sediment and lake sediment was not statistically different for most metals (copper was statistically different). This significant drop in concentration suggests that the major flooding which occurred in 2015 has drastically altered the heavy metal profile of Lake Greenwood and the creeks which flow into the lake. The effect of introducing large volumes of relatively unweathered sediment has an observed lowering of the concentration of heavy metals. For all metals at all sites, the measured concentration of heavy metals in water samples collected was below the screening level established by the US Environmental Protection Agency. Also, our results also call into question the continued use of previously established background concentration of heavy metals after a significant flooding event, as the addition of large volumes of fresh sediment from flooding events significantly changes the heavy metal concentration.