Supporting Data QC Field Spikes SW NAWQA 2012-2015

Field spikes were prepared at 207 stream and river sites as part of the U.S. Geological Survey (USGS) National Water Quality Assessment (NAWQA) project between December, 2012, and September, 2015. At the field site, a depth-and width-integrated environmental sample was collected, and one subsample of the environmental sample was spiked with a known amount of a spike mixture. Both the spiked subsample ("spike sample") and another subsample ("environmental sample") of the original water sample were analyzed for pesticides at the USGS National Water Quality Laboratory (NWQL) by direct injection liquid chromatography with tandem mass spectrometry (LC-MS/MS), and were used to calculate the spike recovery of each analyte. This dataset contains a summary of the spike recoveries for 221 pesticide compounds analyzed by LC-MS/MS at the NWQL in surface water field matrices collected during the period from Dec 2012 to Sept 2015.