Nitrapyrin, a nitrification inhibitor, 6-CPA, a nitrapyrin degradate, and three co-applied herbicides (acetochlor, atrazine, and metolachlor) were measured in surface drains from eights sites in Illinois. Water samples were collected from April to June 2017. The compounds studied are applied to corn, Illinois is one of the largest corn producing states in the U.S. Water samples (1-L) were collected in amber glass bottles using a grab or depth weighted approach. Water samples were filtered (0.7 micrometers), extracted via solid phase extraction (Oasis® MAX cartridge), and analyzed (nitrapyrin and herbicides by gas chromatography with mass-spectrometry; 6-CPA by liquid chromatography tandem mass-spectrometry).