Major and trace element concentrations in water samples collected before and during the September 2013 Colorado South Platte River flood

Record amounts of precipitation fell across the Colorado Front Range from September 9 to 16, 2013, resulting in extensive flooding in the South Platte River and its major mountain tributaries. In this study, the effects of the flood on the City of Boulder, Colorado urban hydrology system were assessed using weekly time-series sampling of 3 source waters (Boulder tap water, Boulder wastewater treatment facility effluent, and Boulder Creek water) conducted from September 20 to October 16, 2012 (n=5) and August 13 to September 30, 2013 (n=8). The effect of the flood on the South Platte River was assessed using a single basin-wide sampling of 5 main stem and 7 tributary sites from September 18 to 22, 2013. Filtered water samples were analyzed at the Boulder sites, and filtered and unfiltered samples were analyzed at the South Platte River sites. Major elements were measured by inductively coupled plasma-optical emission spectrometry and trace elements were measured by inductively coupled plasma-mass spectrometry. Each sample was measured in triplicate and the averages and standard deviations are reported. The results from analyses of associated quality assurance samples (field blanks and field duplicates) also are presented.